Report on Water Cycle

The report presents “An overview of sustainable and self-sufficient water cycle future of Texel Island in the Netherlands”.

Water plays a critical role in the natural environment, supporting all of the major biological and ecological processes, but it is also crucial to the economy, well-being, food production and industrial sector, as well as human health and welfare. As a result, water cycle is an important and fundamental ecological process that regulates, shapes and maintains:weather and climate, landforms and soils, plant and animal communities and finally human society.

Water Cycle according to the online encyclopedia Wikipedia is: “The water cycle describes the continuous movement of water on, above and below the surface of the Earth. The mass of water on Earth remains fairly constant over time but the partitioning of the water into the major reservoirs of ice, fresh water, saline water and atmospheric water is variable depending on a wide range of climatic variables. The water moves from one reservoir to another, such as from river to ocean, or from the ocean to the atmosphere, by the physical processes of evaporation, condensation, precipitation, infiltration, runoff, and subsurface flow. In so doing, the water goes through different phases: liquid, solid (ice), and gas (vapor).”

In our report, as a water cycle sub-system, the term has a more specific perspective and it is related to the Dutch island of Texel and its water system. It considers the water cycle as a whole- holistically and how planning for each element of water services (drinking water, sewage, waterways, stormwater and groundwater) can merge to provide more sustainable solution for the island achieving economic, social and environmental benefits.

Part 1. Sustainability challenge and ambition, problem statement, and research question with regard to the sub-system
Current Situation| Problem statement- Challenges| Ambitions| Research Question| Potentials| Objectives| Water Cycle: S.W.O.T analysis of Sustainable Texel | References

 1. Sustainability challenge and ambition, problem statement, and research question with regard to the sub-system 

1.0 Table of Contents

1.1. Current Situation

1.2. Problem statement- Challenges

1.3. Ambitions

1.4. Research Question

1.5. Potentials

1.6. Objectives

1.7. Water Cycle: S.W.O.T analysis of Sustainable Texel

1.8. References

1.1. Current Situation

Water presence in Texel, as an island, is ubiquity taking into account that water surface (302,04km²) is almost twice in comparison with land one (302,04km²) and the yearly average amount of precipitation is estimated 160 million m³/year. [1]

With population of around 13.600 people and more than 700.000 tourists per year, during hot days in the summer season the water usage can be up to 7500m³, 20% more than the average usage and the yearly water consumption raises up to 1.110.367m³/year according to our calculations (more details on the next chapter: current situation). 

Nowadays, water system for the island can be described as a linear configuration with the following series: The water supply in the island is achieved by an underwater pipeline system from two separate pipes from the main land, which is distanced only 2,5km from the island [1]. After the use, the consumed water is channelled to the sewage system. The amount of consumed water plus a part of rainwater return to the island system as sewage water and it is ended up in the sea, which is the the final step in the current linear system. Although the sewage treatment is sufficient also for the future needs, it presents problems, as we will explain later in the problem statement part and the next chapter. [3]

1.2. Problem statement- Challenges

In general, water issue has economic, environmental and social impact. The water challenges of the island are mainly related to the water supply system, the sewage system, natural disasters (floods+shortage), the wastewater and the amount of consumed water.

Firstly, although, the pipeline system seems an effective solution, there are several drawbacks that accompany water pipelines. Firstly, this kind of water supply makes the island water depended from the mainland, since there is a “water connection” between the two of them. Moreover, the pipeline system by itself presents a series of disadvantages. For instance, the actual construction but also maintenance of a major water pipeline is extremely expensive. With manufacturing, labor, installation and maintenance, pipeline projects can cost billions of dollars. Because in this project we have to deal with an existing situation, the attention is given to the maintenance, which must be done every day in order to keep the pipeline working effectively. Pipelines need to be monitored continually and water quality must be constantly checked. Furthermore the pipes can disrupt ecosystems, ruin scenery, and act as an obstruction. Underground pipelines require huge trenches to be dug, also disrupting the land.

In conclusion, pipelines from the mainland (as a recent solution in order to ensure independence from the mainland) are only temporary solutions to the problem. They are too expensive for future use due to high tariffs and you cannot count on safety. [4]

A brief research on the societal water demands on Texel has shown extreme weather caused floods and water shortages on the island in the past years. More specifically, last August heavy rains caused floods on several parts of Texel. On the second part of august 25 to 30 mm of rain has fallen. Despite the installed rain drainage system about 50 cm of water covered the Vliestraat in Oosterend. Other parts of Texel, such as De Cocksdork and Den Burg also experienced flooded streets, hotels and tourists housing. [5]

On the other hand Texel experienced a water shortage in July 2013 when a heat wave hit the Netherlands. A leakage of the pipeline system between the island and the shore reduced the available water capacity and trucks transporting water were used to fulfill the rising demands. Since the pipeline lies at a depth of approximately 25 meters and divers can only work on it in between tides it took nearly 4 months to repair the leak. [2]

These two incidents may be experienced more often as the weather in the Netherlands is becoming more and more extreme.

In addition, as the amount of visiting tourists is increasing, yearly water demand on Texel is likely to increase even more. A bigger capacity of both the drainage system and the water supply system would be needed in order to fulfill the future demands.

The last challenge is the amount of wastewater. Nowadays, there are no actions on the island regarding the reuse and recycle of wastewater and as a result, all the amount of water that falls on the surface of the island is challenged in the sewage system as wastewater.

1.3. Ambitions

The term sustainability has been defined in many different ways. More generally, sustainability involves the simultaneous pursuit of economic prosperity, environmental quality and social equity and the need to perform not against a single bottom line but against this triple bottom line [12]. Our design tries to follow this “triple bottom-line approach” (TBL or 3BL), offering social, environmental and economic benefits. Starting with the social and environmental impacts, which will be instantly visible following by the economic benefits, which will be occurred some years later (analytically these benefits will be explained in the next chapters).

As a water cycle sub-system, our general ambition is to convert Texel in a sustainable and an autonomous island but also to reach the 3P needs (People (both locals and tourists), Private, Public) sectors.

Firstly, a key issue in our design is how to handle and combine the ‘top-down’ approach, which includes the strategic overview of the island as whole, and the ‘bottom-up’ approach, which articulates citizens’ but also tourists' demands.

Specifically, we aim to provide solutions that will support the realization of the vision of a self-sufficient Texel in 2020 and 100% “disconnection” from the mainland.The aim is to become autonomous regarding drinking water by developing its own sustainable system for water by exploiting the existing water sources  and systems (rain and current sewage) but also the amount of wastewater.

1.4. Research Question

The biggest question now is: do we accept the 'default traditional future', or do we strive to create our 'preferred future', keeping in mind the impact that our decisions we make today will have on future generations (considering 2065).

What water technologies, techniques and systems can be applied in Texel, in order to convert it in a sustainable island and simultaneously to provide its own drinking water in order to be self-sufficient and independent?

1.5. Potentials

The potentials are related to the water presence in the island but also to current innovation and sustainable water technologies.

In Texel, the annual precipitation is 996mm/year with the peak point during October (245mm) and the total area of the island is 161,12km². This means that the annual amount of rainfall water in the island is estimated 160 million m³/year. The annual water demands of the island are 1,1 m³/year, which means that in an unrealistic scenario if a huge rain collector covers the whole island can be served around 1500% of the island needs. In a more realistic scenario, if the roofs of the existing buildings are used as rain catchment surfaces are able to cover a big percentage (maybe 30%) of their needs. [1] [6]

Furthermore, the island can exploit the seawater in order to produce fresh water but also energy.

Last but not least, it is the installation of innovative and sustainable solutions in order to recycle wastewater but also produce water through them.

1.6. Objectives

Water is a fundamental resource challenge facing Texel, and its planning and management is a critical underpinning of Texel’s economy, society and environment. 

Our sub-system objects are focused on four different perspectives related to the water cycle. These are summarized the R³P idea, which is explained by:

REDUCE (estimated percentage 10%)

REUSE (estimated percentage 20%)

RECYCLE (estimated percentage 80%)

PRODUCE (probably not the most efficient solution)

The R³P design aims to convert the linear configuration of the existing system to the circular  one by achieving the water cycle. (these will be explained deeply in the chapter 4: the comparison of the current and future system)

To achieve the R³P concept we will look into the current state and previously attempted innovations technologies. Our goal is to find new solutions and to increase the efficiency of urban water systems by rethinking old paradigms and developing new solutions. Different technologies like rainwater harvesting, desalination of the seawater, effective stormwater management etc. can cover the R³P idea by reducing, reusing, recycling and producing.

Having a lot of different technologies in mind for reuse, recycle and production, we will be able to choose some of them or reject other organising the best future solution. As a result, our main objective is to develop an overall strategic approach  achieving sustainable urban water management in the island of the future. 

Finally, although people awareness seems to have limited influence, especially because we have to deal with a big amount of tourists, if we are able to reduce the daily needs at least 10% (according to the Dutch standards of water consumption 128l/p/d) it will be very beneficial. 

From this we can start evaluating different possible sustainable technologies and designing different possible scenarios in all the four perspectives and depending on available time, we will decide to focus on one promising integrated system of possibly different technologies. An interesting possibility may be to discuss solutions with stakeholders involved like the municipality, HHNK (Hoogheemraadschap Hollands Noorderkwartier) sewage treatment company, PWN Water Company or even VVV tourism organization. [2] [10] [11]

1.7. Water Cycle: S.W.O.T analysis of Sustainable Texel

A SWOT analysis (alternatively SWOT matrix) is a structured planning method used to evaluate the strengths, weaknesses, opportunities and threats (SWOT) involved in order to develop a strong proposal design. More specifically, in Texel case, it is the method strategy that can be followed in order to convert the Texel in a sustainable island in a more sufficient way. It involves specifying the objective of the proposal and then identifying the internal and external factors that are favorable and unfavorable to achieve that objective. [8]

S.W.O.T. is an acronym that stands for Strengths, Weaknesses, Opportunities, and Threats.

Strengths (internal positive factors): characteristics of the project that give it an advantage over others.

Weaknesses (negative factors): characteristics that place the project at a disadvantage relative to others and they have to improved.

Opportunities (potentials) (external positive factors): elements that the project could exploit to its advantage

Threats (external negative factors): elements in the environment that could cause trouble for the business or project

Our water cycle sub-system in Texel Island needs to ask and answer questions that generate meaningful information for each category to make the analysis useful and find their competitive advantage.

The following strengths, weaknesses, opportunities and threats have been identified for the water cycle sub-system of the Texel Island.

Strengths

Weaknesses

Opportunities

Threats

1.8. References

[1] http://en.wikipedia.org/wiki/Texel

[2] https://www.pwn.nl/overpwn/pers/Paginas/dossiertexel.aspx

[3] http://www.being-here.net/page/5867/water-cycle

[4] http://academic.evergreen.edu/g/grossmaz/SUPPESBJ/

[5] http://www.texelsecourant.nl/lees/18645/wateroverlast-door-hevige-regenbuien

[6] http://www.whatstheweatherlike.org/netherlands/texel.htm

[7] [http://en.wikipedia.org/wiki/Water_supply_and_sanitation_in_the_Netherlands]

[8] http://en.wikipedia.org/wiki/SWOT_analysis

[9] http://www.cbs.nl/en-GB/menu/themas/natuur-milieu/publicaties/artikelen/archief/2013/2013-3768-wm.htm

[10] http://www.vvvzeeland.nl/en/vvv-tourist-offices

[11] http://www.hhnk.nl/werk_in_de_buurt/gebiedspagina's/texel

[12] http://en.wikipedia.org/wiki/Triple_bottom_line

General figures 

The municipality of Texel consists of 170km² land and 416km² of water (sea and inland water). These figures show that there’s plenty of (saline) water on or nearby the island.

According to the holiday website Zoover, the average annual rainfall is 996mm. A more scientific source for this amount cannot be found yet.  

Current water use

According to the website of PWN (described under actors) the average water use is 125L/person per day. Assuming 13640 permanent inhabitants and 40.000 tourists would mean an average use of (13600 + 40.000) x 125 = 6700m³ per day. 

The yearly amount of distributed water on the island is about 1.600.000m³ according to data of the PWN. PWN furthermore states that on hot days during the tourist season the average use per day of the whole island is 7500m³ of drinking water.

Actors involved

- PWN (Provinciaal Waterleidingbedrijf Noord-Holland). This institute is responsible for all water supply systems in the province of Noord-Holland, including Texel. The 2 pipelines that connect the island with the mainland for waters supply and all other drinking water supply lines are owned and maintained by this institute.

- HHNK (Hoogheemraadschap Noorderkwartier).  This governmental body is responsible for water management, maintaining dikes, treatment of waste water and maintenance of the sewage system.

- Municipality of Texel. The municipality is partly owner of the sewage system and takes care of the maintenance of some parts of the system .

Prevailing technologies

Unlike in the past and other Wadden islands, Texel does not produce any drinking water on the island. Because of the large number of tourists during the summer season not enough water could be generated on the island. The maximum capacity of drinking water production was already reached in 1966 and was about 540.000m³. The island now depends on 2 pipelines that supply the island with drinking water.  

Since July 2012 Texel has one big water treatment facility in Everstekoog (before this there were 5 smaller ones). Every larger village has a storage tank for the wastewater of the households before it is transported to the treatment plant Everstekoog. The sewage system does not separate waste-water and rainwater, which results in need for more capacity during rainfall. The smaller villages have a tank of 20m3, the biggest town Den Burg 100m3. The water is pumped to the treatment plant from these tanks according to the amount of water inside. This allows a changing distribution of waste water, according to the intensity that is required. This is a very useful feature for the water management on the island.

The treatment facility Everstekoog treats wastewater from all the villages on the island and has a capacity of 8 million litres or 8024m³ water per day. The water spends about 1-2 days in purifying tanks were the water is purified and cleaned by billions of bacteria.  After this first processing the water is already clean, but more nutrients have to be added. This process takes place in the helophyte filter on a constructed wetland of 9 hectares for 3 more days.

After these 5 days the water is released to the ditch system. A surplus of treated water can be released in 2 directions and this effluent is powered by 2 pumping stations on both sides of the island that end up in the sea. The flowrate can be up to 350m3/minute. The treatment process is already very sustainable, except the fact that rainwater also enters the treatment system and that not all cleaned water is stored in situations of a surplus.

The ditch-system acts as one big water buffer. The water level in winter is on average 40cm lower than during summer. In February they start stacking the water in the ditches by means of 900 locks (of which only 56 are automated) to create this buffer and allow a natural stream. This water is then used in the summer to irrigate the land.

Houses and smaller communities that are far away from the cities are not connected to the centralized sewage system. A total of 11 smaller IBA’s (small scale water treatment facility) accommodates the treatment of the waste water here.

Relations

In 2005 the municipality of Texel and HHNK agreed to start collaborating in the waste water processing and interventions to improve the water system.

In the interview with Nico Tessel (employee of HHNK) we concluded that cooperation only exists in case of emergency. This means that municipality and HHNK work closely together in periods of extensive rainfall to minimize the effects. More cooperation is not present due to lack of budget the municipality is facing. 

We have found no other relations or cooperation between the actors.

Rules & regulations that organize the system

This can be divided into agreements between actors or goals set by the municipality and governmental legislation.

- Waste water agreement 2005

- Masterplan Water for Texel (2006).

- Water footprint Texel (2012)

Legislative regulation regarding the water system is defined in the following laws:

- Leveringszekerheidwetgeving                                             - Lozingbesluit Afvalwater Huishoudens

- Drinkwaterwet                                                                  - Drinkwaterbesluit                                      

- Wet Verontreiniging Oppervlaktewateren                          - Wet milieubeheer

Since 2009, most of the legislation is combined into the overall legislations of the waterwet.

During our visit on the treatment plant we also found out that quality of the treated water is very important. A robot takes automatic samples of the water quality which are send every 2 weeks to a testlab in Hoorn were the quality is checked.

Current unsustainabilities.

Texel does not have its own drinking water supply, but is supplied with drinking water via 2 pipelines that are connected to the mainland. In the summer of 2013 one of these pipelines broke down. This event happened in the middle of the tourist season and on top of that a heat wave hit the Netherlands. Because of fear of a water shortage PWN sent 10 tank-cars containing 30.000 litres of water to the island every day to make sure there was enough water available. The fixing of the pipe took about 3 months because the pipes are 25m below sea level which makes it an expensive and labour intensive job.

The failure of the pipeline illustrates the drawback of not having an own water supply.  On the other hand it is now not economically feasible to have a drinking water facility due to the low population density and the high demand during tourist seasons.

Furthermore the sewage system is not able to cope with extensive rainfall. In august 2014 heavy rainfall caused flooding of some parts of the island. At some places the water was half a meter high, causing a lot of inconvenience. Due to climate change precipitation patterns will change causing more rain to fall in shorter periods, but also longer dry periods. Events of extensive rainfall or longer periods of drought are more likely to occur in the future. This indicates that a bigger buffer capacity is needed to have sufficient fresh water supply during periods of drought.

Another major drawback of the current sewage system is that the water is not clearly separated into waste-water and rainwater. Due to out-dated systems in parts of the island rainwater enters the sewage system. This increases the amount of water the treatment plant has to treat, while the rainwater does not need any treatment.

The new water treatment facility releases the water to the surface water after processing. This relatively clean water might be (re)-used in a more efficient way to cut down the average water use.

Trends & initiatives

In 2010 the organisation Duurzaam Texel (sustainable Texel) distributed a water saving feature among all Tesselaars that they could mount on their home water taps. This small polymer cap which is placed at the end of the water tap lets less water through while the pressure remains the same. This will annually save 3000L drinking water per household, and 18 million litres for the whole island. 

To reduce the use of plastic bottles the voluntarily organisation AquaPLUS started an initiative to promote the use of tap water. The project is called AquaTX and is initiated to reduce the plastic waste found on the beaches of Texel. Tap water is a good alternative and 400 to 1000 times cheaper than water from a well but besides that it doesn’t need packaging and therefore has less environmental impact compared to bottled water. To promote tap water drinking glasses with the logo of AquaTX are sold to bars, restaurants but also schools and offices. Besides trying to change the behaviour of people this organisation also organizes events to clean up the beaches in cooperation with schools.  

The consultancy and engineering firm Antea Group recently came up with the initiative of a water footprint. Clean water seems obvious, but it takes increasing effort to maintain the quality of drinking water and therefore innovative solutions in the water chain are needed. Antea Group advises government bodies and commerce in this challenge. They are working on a toolbox to develop sustainable water management and reducing of water risks for the economy. 

An important trend on Texel is salt water agriculture. Different initiatives and projects have started which deal with salt water farming. The first crops, saline sea-kale were already on the market in 2008 and developments did not stop there. Farmer Marc van Rijsselberghe now produces a variety of saline crops such as potatoes, onions, roots and cabbages. Who knows what genetic modification can do to make other plant species suitable for saline agriculture. By growing crops with saline seawater, land does not have to be irrigated with fresh water, which would be very beneficial towards a self-sustaining water system on the island. 

Another agricultural pilot project on Texel is a freshwater storage basin.  Due to climate change the availability of freshwater will not be as regular as it is now because rainfall patterns will change. More rain will fall in shorter periods, causing longer dry periods. This project investigates how farmers can have their own freshwater supply to overcome periods of drought. It’s a combination of a basin in which rainwater is collected that felt on the roofs and a drainage system to irrigate the land.  This pilot is initiated and financed by the province of Noord-Holland and ends by the end of 2015. The municipality of Texel and HHNK are also involved in the project.

Sources  (linked in text).

https://www.croon.nl/uploads/croon.nl/tbi3_downloads/126/file/rwzi_ texel__texelse_courant_030812.pdf  -> information about water treatment facility

http://www.texelsecourant.nl/lees/18645/wateroverlast-door-hevige-regenbuien -> about extensive rainfall

http://www.texelplaza.nl/nieuws/artikel/035182/  -> about extensive rainfall

http://www.zoover.nl/nederland/waddeneilanden/texel/weer  -> weather data

http://www.noordhollandsdagblad.nl/stadstreek/denhelder/article23653173.ece/Tankwagens-met-extra-drinkwater-naar-Texel?lref=sll -> about pipeline that broke down

http://www.trouw.nl/tr/nl/4332/Groen/article/detail/3108914/2012/01/06/Zout-water-als-vriend-van-Texelse-landbouw.dhtml  -> salt water agriculture

http://www.netafim-cmt.com/nl/nieuws/1357200660/Zoetwaterberging-op-Texel-gestart -> freshwater storage

http://nl.anteagroup.com/en/sector/water-technology -> Antea Group

http://deltaproof.stowa.nl/Upload/Deltaproof/zoet-zout/Zoet-zoukrantdef-1.pdf -> salt vs fresh water

http://www.texel-plaza.nl/nieuws/artikel/043552/30/ -> tap water saving  

http://www.duurzaamtexel.nl/actueel/tips-om-water-te-besparen --> water use in general 

http://www.waddenzee.nl/Marc_van_Rijsselberghe_zilte_teler.2977.0.html -> salt water farmer 

http://duinenenmensen.nl/wp-content/uploads/2014/12/Drinkwater_op_een_eiland_maandbladH2Onov13.pdf -> data about water use

http://www.texel.nl/document.php?m=23&fileid=38613&f=94a998e527daa1801ed756f73a293520&attachment=1&c=35685 -> masterplan water Texel 2006

In this chapter we will introduce and evaluate possible water saving technologies. We will choose the best technologies for our future system which will be combined in the plan visualized in part 4.

3.1 Water reduction:

Since Dutch water is relatively cheap saving water won’t lead to enormous savings on the financial field. However, cleaning water consumes lots of energy, the chemicals used end up in the ecosystem and ground water levels are disturbed, so it is important to pay attention to your water usage.

The Dutch average daily water usage is 120 liters per person, washing, cleaning and flushing the toilet consumes the biggest part of this water:

3.1.1 Awareness

By creating awareness among the Tesselaars they can start reducing their water use immediately. Info graphics or informative meetings should provide the inhabitants and tourists with tips in order to save drinking water. Small changes on a large scale can have big impacts:

• Since taps run with approximately 12 L/min, don't forget to close it in between actions. Closing the tap while you brush your teeth, for one minute, twice a day, will save 20% of your water usage!
• Leaking taps can consume enormous amounts of water; by checking all taps in your house you can prevent unnecessary waste of water. A dripping tap often wastes around 5 liters a day, a leaking toilet sometimes even 300 liters a day.
• Showering 1 minute less, assuming you shower on a daily basis, will reduce your water use by more than 7%.
• A bath consumes twice as much water (110 L) compared to a five minute shower.
• Fill up the (dish)washing machine in order to use it as efficiently as possible. An average dishwasher uses 22,5 liters each turn, a clothes washing machine even 150 L. Assuming that by filling your machine you can prevent one wash a month and one dish a week you'll save 240L of water in a month, 8L of water per day, so another 7%.

3.1.2 Technological changes

To enhance the water savings that you can incorporate several, small, technical devices. For instance:

• water saving shower heads consume 5 L/min instead of 8,7 without a reduction in comfort
• water saving tap heads can save up to 3000 L/year and cost only 2 euros
• heat exchangers can be applied to make use of the waste heat after a shower
• modern (dish)washing machines are often much less energy and water consuming
• the same goes for modern toilets, you can also use something to partly "fill" the reservoir of an old toilet
• Grey or rainwater systems can replace lots of the clean water; this toilet (figure) saves 25% clean water by using the sink water to flush.
• Rain water tanks are a great step towards water saving, without any extra work the water is perfectly suitable for irrigation and cleaning in and around the house. With tanks up to 2000 liters there can always be water available. If this water is used for outside purposes 7000 liters of drinking water can be saved annually.

3.2 Precipitation systems

As we've seen Texel deals with large amounts of atmospheric precipitation. Collecting and using this fresh water can reduce tap water use to a large extend. The systems filter the water and collect it in a bag or tank underground or underneath the house. The reservoir can be connected to the toilets, washing machine and all other taps which aren't used for drinking water. The systems are not only friendly for the environment; a good system saves 50 euros on water using only 3 euros of energy.

The roof of an average Dutch house catches 80.000 liters of rainwater on a yearly basis, this is nearly enough for an average two person household. Rainwater harvesting is beneficial because provides an independent water supply during regional water restrictions by reducing the existing water supply and simultaneously providing water during the whole year, especially in drought seasons by reducing the run-off, the erosion and the contamination of surface water.

The main components of a rain harvesting system are a catchment surface, which can be also the roofs of the existing buildings or a new catchment surface, the conveyance system (pipes), the storage area, which ranges in sizes according the catchment surface and can be under or on the ground and the treatment system (filters, pump).

3.2.1 Drinking water from rain water

Can rainwater be made safe to drink? Yes. How safe? As safe as your well or tap water. How do you make it safe for indoor use? By filtering and purifying it. As a result, it can also use as potable water, as rainwater is substantially free of salinity and other salts. Bringing rain indoors could save the expense and environmental costs of treating and transporting water.  

Contaminants in water may include algae, air pollution, bird excrement, and leaves, sand, and dust. Local wells have dealt with these problems for decades. Installation of filtration and purification equipment can remove these contaminants at home as well.

It is important to take measures and keep foreign matter out of the incoming rainwater. First flush devices, gutter screens and other screening mechanisms keep the rainwater as clean as possible before it enters the conveyance system. Using screens and filters will greatly reduce maintenance and lengthen the life of the pump and filtration/purification system. To keep sediment where it belongs, at the bottom of your tank, screen incoming rainwater, give the remaining sediment time to settle, avoid disturbing it, and don’t pull water from the bottom of the tank. Use a floating filter, which extracts water from the middle of the tank, leaving sediment undisturbed. Next is filtration, which removes debris from the water. Disinfection or purification follows, which kills contaminants and removes harmful substances that may be present. Filtration is included in every system, even simple irrigation systems. Examples of filtration systems include: screen filters, paper filters, and carbon or charcoal filters.

3.3 filter technologies

3.3.1 Natural filter technologies: The helofytenfilter

There are several natural ways to clean water, these are not only environmentally friendly, they are also relatively cheap and reliable since they don't depend on technologies.

In a helofytenfilter swamp plants are used in order to clean waste water. After solid particles are removed in a septic tank, the water can be pumped into the filter. This filter consists of a one meter thick layer of sand with a layer of small stones above and underneath it (see picture). The roots of the plants have grown through the sand and as the water gradually sinks down some air is dragged into the ground as well. This creates optimal surroundings for water cleaning bacteria which live in symbiosis with the helophytes; those bacteria clean the water up to 99%!

Since the pump only has to work during short time intervals, gravity will do the rest of the work, energy consumption of such filters is really low. Since all waste materials are being demolished by the bacteria, which can provide as food for other organisms, there is hardly any residue.

3.3.2 Desalination towards sustainable ways - turning seawater into drinking water

Global demand for water continues to increase due to population growth and economic development, whilst freshwater sources are becoming scarcer due to increasing demand for natural resources and the impacts of climate change. Desalination of seawater and brackish water can be used to augment the increasing demand for fresh water supplies.

It is referred to the removal of salts and minerals in order to produce water suitable for human consumption or irrigation. Due to relatively high-energy consumption (often using energy supply from fossil fuel sources which are vulnerable to volatile global market prices as well as logistical supply problems in remote and island communities and are therefore not sustainable), the costs of desalinating seawater are generally higher than other alternatives (like river water, rain water or water recycle), but alternatives are not always available. Moreover, the large amounts of energy have also an outsized impact on the environment. Simultaneously, desalination systems can damage the aquatic ecosystems by releasing large volumes of highly salty liquid brine back into the water.

Engineers and entrepreneurs across the globe are now trying to devise greener and more sustainable ways for desalination. Some are inventing new alternatives. Technologies that shrink energy and brine or they are chemical-free or even energy-efficient enough to run on renewable energy sources.

Current information on desalination shows that only 1% of total desalinated water is based on energy from renewable sources. Renewables are becoming increasingly mainstream and technology prices continue to decline, thus making renewable energy a viable option. While desalination is still costly, declining renewable energy technology deployment costs are expected to bring this cost down in the coming years. This is of particular interest to remote regions and islands with small populations and poor infrastructure for freshwater and electricity transmission and distribution.

There are two broad categories of desalination technologies. Thermal desalination uses heat to vaporize fresh water, while membrane desalination (reverse osmosis) uses high pressure from electrically powered pumps to separate fresh water from seawater or brackish water using a membrane.

Thermal Desalination Technologies: Thermal desalination involves distillation processes where saline feed-water is heated to vaporize, causing fresh water to evaporate and leave behind a highly saline solution, namely the brine. Freshwater is then obtained from vapor cooling and condensation.

Membrane Desalination Technologies: Membrane desalination uses membranes to separate fresh water from saline feed-water. Feed-water is brought to the surface of a membrane, which selectively passes water and excludes salts.

Desalination based on Renewable Energy: Desalination based on the use of renewable energy sources can provide a sustainable way to produce fresh water. It is expected to become economically attractive as the costs of renewable technologies continue to decline and the prices of fossil fuels continue to increase. Using locally available renewable energy resources for desalination like rain, tides, waves, which are also related to our water cycle sub-system is likely to be a cost-effective solution particularly in remote regions, with low population density and poor infrastructure for fresh water and electricity transmission and distribution. As a result, the solution is to find a sustainable solution to produce renewable energy and afterwards to use it in order to desalinate seawater. The placement of a large scale desalination plant in the middle of the sea has distinct advantages over land based desalination - only at sea can we gather a plurality of renewable energy sources - like solar, wind, tide, current, OTEC [ocean thermal energy conversion].

The dominant energy source is solar photovoltaic (PV), which is used in some 43% of the existing applications, followed by solar thermal and wind energy. The right combination of a renewable energy source with a desalination technology can be the key to match both power and water demand economically, efficiently and in an environmentally friendly way.

An example: Carnegie Wave Energy is planning to open the world’s first zero-emission wave powered desalination plant on Garden Island in Australia. Using the Perth Company’s proprietary “CETO technology,” the two-megawatt pilot project will operate with multiple submerged buoys tethered to pumps that funnel pressurized water to turbines onshore. There the water can either be harnessed to create electricity or to run and supply water for a reverse osmosis desalination plant. The CETO wave power converters are the first to be fully submerged under water, keeping them safe from the effects of major storms and reducing visual impact. The project on Garden Island in Western Australia will be a grid-connected, commercial scale operation that will demonstrate the technology’s viability, record its interactions with the environment, and help provide fresh water in accordance with the West Australia Water Corporation. Desalination is an important part of Perth’s long-term strategy to maintain a supply of clean drinking water and the Carnegie Wave Energy technology will secure a means to provide this precious resource without relying upon energy-hungry machinery. Instead, by creating its own power, the CETO infrastructure can cut down on greenhouse gas emissions while also generating electrons and purified water. The project is expected to begin construction in 2014.

3.3.2 Produce drinking water from air humidity

Even though there is a shortage of surface or groundwater, in often-considerable quantities, water is to be found in the air. Moreover, as a result of global warming it is to be expected that the water content of the atmosphere will increase further because of the rising temperatures. So that this water resource can be developed as a source of drinking water. The entire process consists of two parts. First, the humidity from the air is absorbed by a highly concentrated saline solution (brine) and thus bound. Then this diluted saline solution is distilled and the water separated from the saline solution is condensed as drinking water (desorption).

Some example are the Skywater® machine and the atmospheric water generator (AWG), which we will explain below.

The Skywater® is a machine, which makes drinking water from humidity in the air. It is alleviate dependence from the local water supply, by harvesting enough fresh water from the air to supply a single-family home, office, and much more. The Skywater® 14 home / office machine may be the most convenient kitchen appliance since the refrigerator. No more lifting heavy water bottles for your water cooler, simply plug in Skywater® products and enjoy fresh, great tasting water for pennies to the liter.

The second example is the atmospheric water generator (AWG), which is a device that extracts water from humid ambient air. Water vapor in the air is condensed by cooling the air below its dew point, exposing the air to desiccants, or pressurizing the air. Unlike a dehumidifier, an AWG is designed to render the water potable. AWGs are useful where pure drinking water is difficult or impossible to obtain, because there is almost always a small amount of water in the air that can be extracted. The two primary techniques in use are cooling and desiccants. The extraction of atmospheric water may not be completely free of cost, because significant input of energy is required to drive some AWG processes, sometimes called "trading oil for water". Research has also developed AWG technologies to produce useful yields of water at a reduced (but non-zero) energy cost.

3.4 solutions for Texel

3.4.1 Awareness plan - reduce

In addition to the list mentioned above, there are much more small changes in and around the house which can have significant effect on your water usage. In order to involve the Tesselaars to their new sustainable future we start by raising their awareness and responsibility. The campaign should teach them that just by reducing their showers by one minute, closing the tap while brushing their teeth and filling up their washing machines in order to reduce their amount of washes, they can already reduce their water use by 25%. In addition they should feel responsible for their independency of the mainland: by saving 25% water, the pipeline might become unnecessary in the future.

A special function lays with the owners of hotels and other tourist accommodations; they will not only be responsible for their own water use but must also inspire their guests to do so. This should be done in a similar way to the cards we're already familiar with in hotels that tell you to re-use your towel.

3.4.2 Building level plan - reduce

When interest has grown among the inhabitants they should be motivated to contribute to their water saving plan more actively. Several packages must be available in order to turn your house or tourist accommodation into a water friendly one. The packages should be available in different gradations: from low-cost ones including saving water taps, shower heads and a rain water tank for outside use, up to the ultimate package where, especially new projects, incorporate grey water systems combined with precipitation collection.

These technological changes will not only reduce the drink-water usage by another 25%, it will also provide Texel with a unique selling point. Since the island is ahead of the mainland, by stimulating local companies to contribute to the distribution of sustainable solutions, the local economy will be stimulated by "exporting" Texel its sustainable expertise. This will also attract eco-tourism, stimulating the wish for tourists to contribute to the plan as well.

3.4.3 Rain water usage - reuse

Due to the recent floods and draughts there is need for an extra buffer on the short term. By incorporating these buffers, which will mainly be precipitation tanks, to grey water points, like swimming pools, showers and washing machines on camp sides, less drinking water will be spoiled by tourists. Gradually, as the technological changes will be incorporated in more and more buildings, the buffers, of different sizes, will become more effective.

3.4.4 Drinking water cleaning - recycling

The last step to provide independency for the Tesselaars is to create their own drinking water cleaning facility. Since there is no ground water source on Texel and desalination and using air humidity is still very energy consuming, recycling water is preferred. However, there are still no good, legal methods for this, making it a future goal.

This is an infographic on the future water system of Texel. Inforgraphic by Jesper Goorden, Text by Elia Galiouna.

According to the current situation, the existing water treatment plant is already using a very sustainable way to clear the wastewater. However, we still think there is room for improvement. This proposal design is divided in three phases and three levels. The phases are reduce, re-use and re-cycle and the levels are personal-, building- and island level. Our main focus is on the first phase, which although it seems the most obvious concept, it is the easiest, cheaper and most efficient solution.

Water Reduction

Since Dutch water is relatively cheap (approximately 60euros/person/year), saving water won’t lead to enormous savings on the financial field. However, cleaning water consumes lots of energy, so it is important to pay attention to your water usage.

The Dutch average daily water usage, as it is analyzed above, is 120 liters per person. Washing, cleaning and flushing the toilet consumes the biggest part of this water. The reduction phase is divided in two parts: awareness on a personal level and small technological changes on a building level.

Awareness

In order to involve the Tesselaars to their new sustainable future, we will start by raising their awareness and responsibility. The campaign should teach them, as well as visitors, that just by reducing their showers by one minute, closing the tap while brushing their teeth and filling up their washing machines in order to reduce their amount of washes, they can already reduce their water use by 25%.

A special function lays with the owners of hotels and other tourist accommodations; they will not only be responsible for their own water use but must also inspire their guests to do so. This should be done in a similar way to the cards we're already familiar with in hotels that tell you to re-use your towel.

Info graphics or informative meetings should provide the inhabitants and tourists with tips in order to save drinking water. Small changes on a large scale can have big impacts.

Some of these small changes could be:

• Taps run with approximately 12 L/min, so don't forget to close it in between actions. Closing the tap while you brush your teeth, for one minute, twice a day, will save 20% of your water usage!
• Leaking taps can consume enormous amounts of water; by checking all taps in your house you can prevent unnecessary waste of water. A dripping tap often wastes around 5 liters a day, a leaking toilet sometimes even 300 liters a day.
• Showering 1 minute less, assuming you shower on a daily basis, will reduce your water use by more than 7%.
• A bath consumes twice as much water (110 L) compared to a five-minute shower.
• Fill up the (dish) washing machine in order to use it as efficiently as possible. An average dishwasher uses 22,5 liters each turn, a clothes washing machine even 150 L. Assuming that by filling your machine you can prevent one wash a month and one dish a week you'll save 240L of water in a month, 8L of water per day, so another 7%.

Technological changes

To enhance the water savings on a building level, several small technological changes can be incorporated to the existing building system. We are proposing two packages, the basic (low-cost solution for existing building) and the advanced, which can reduce the consumed water 20 and 40% respectively.

Basic Package: The basic package is referred to existing buildings. It costs 70 euros, saving 20% of consumed water and includes:

1. Water saving showerheads, which consume 5 L/min instead of 8,7 without a reduction in comfort. Specifically, water saving tap heads can save up to 3000 L/year and cost only 2 euros.

2. Toilet Displacement Devices: Plastic containers (such as plastic milk jugs) can be filled with water or pebbles and placed in a toilet tank to reduce the amount of water used per flush. By placing one to three such containers in the tank, more than 3,8 liters of water can be saved per flush, which is translated in 18liters/person/day and 6570liters/person/year. This device cost only 5euro.

3. A simple water harvesting system, which will collect the rainwater from the roofs of each building and then storage it in a water tank outside of the building can be easily installed. This rainwater can be used for irrigation and other outside activities like washing cars etc. can save 1500L/year. The needed equipment consists of the existing roof, pipes and a water tank of 300liters with a total cost of 50 euros.

Advanced Package: This package is for new or renovated building, aiming to save 40% and  incorporating new modern devices such as washing machines and toiles with grey water systems combined and precipitation collection.

1. Modern toilets: Older toilet cisterns with a syphon-flushing system hold between 9 litres and 12 litres of water. Modern toilet cisterns hold about 6 litres of water.

2. Modern washing machines, both for clothes and dishes, are often much less energy and water consuming

3. Heat exchangers can be applied to make use of the waste heat after a shower.

4. The use of waste water for flushing toilets, which can safe 25% of the yearly water consumption.

5. Rainwater harvesting: The roof of an average Dutch house catches 80.000 liters of rainwater on a yearly basis, this is nearly enough for an average two person household. Rainwater harvesting is beneficial because provides an independent water supply during regional water restrictions by reducing the existing water supply and simultaneously providing water during the whole year, especially in drought seasons by reducing the run-off, the erosion and the contamination of surface water.

Water Re-use

As we've seen Texel deals with large amounts of atmospheric precipitation. Collecting and using this fresh water can reduce tap water use to a large extend. This phase is mainly applicable  to the re-use of the rainwater on the building (as it is already mention in previews phase) and island level, creating grey water for uses such as filling swimming pools, showers and washing machines on camp sides and in general for all other taps which aren't used for drinking water.

Re-cycle

The last step to provide independency for the Tesselaars is to create their own drinking water cleaning facility. However, there are still no good, legal methods for this, making it a future goal.

In order to move from the current subsystem towards our sustainable proposal certain steps are necessary. In this paragraph we will provide an action plan for 2020 including the steps towards a closed and improved water cycle in 2065.

5.1 Reduce

The reduction of (drinking) water consumption is the first step towards a sustainable water system. By creating awareness the water use per person must drop with 25% within the next 5 years. By adding technological changes on a building level, the total amount of drinking water consumption must be halved in 2050.

5.1.1 Awareness

Though it might seem a small step, creating awareness, and thus changing habits, will be a time-consuming task. Especially since a big part of Texel its inhabitants are always tourists which makes them a lot harder to reach. However, since there are no big investments involved to this step it is possible to start as soon as possible. In order to reach tourists as well the savings on water use must be visible on the island, this will take some investments but must be achievable within 5 years.

5.1.2 Building level technologies

In order to help the Tesselaars to reduce their water use technical interventions need to be applied. As is stated in chapter three, there are techniques on all kinds of scales, from tap heads and rain water tanks to complete building systems. In five years a package should be available for all households willing to participate to an independent, sustainable Texel, this will not only contain tips but also some of the small household technologies like water saving shower heads in order to enhance a reduction of water use.

With this new awareness a market has evolved around further water reduction, creating more and more demand for the start-up companies that evolved at Texel which provide sustainable solutions on a building level. In the next 35 years such companies will be involved in all projects on the island so almost every building has a more sustainable water system in the end.

5.2 Reuse

On the larger scale, the improvements demand a larger timescale. We propose to collect more (rain)water in new buffers and to create a new water cleaning facility which enables the islanders to close the water cycle. The location and planning for these systems need time and should be made by or in cooperation with Tesselaars. This will not only help to create support amongst them, it will also enhance the awareness the project needs to succeed. The planning of the system will probably take some time, but the aim is to start building within 5 years.

5.3 Recycle

There are no closed water cycles yet because the law does not allow drinking water to be created from waste water. The planning and building of the new treatment plant will thus take some more time. Since there have recently been problems with the water system during droughts and heavy rainfall, the buffers should be built as soon as possible.

Preferably local (start-up) companies will be used to execute the improved plans. If they create expertise on the sustainable market this can become an important export product for Texel. This will also create awareness among the tourists and might even attract a new kind of visitors to the island, interested in their sustainable solutions.

So by creating awareness within the next 5 years, developing household systems, planning a new water treatment plant and creating new buffers. Texel its water cycle will be fully improved within 35 years, maybe even faster!

Linkages with all other sub-system
The modular approach of Engineering Sustainable Development Course

The Engineering Sustainable Development course is based on the idea of modular design, where a complex and big system is divided into smaller, distinct parts or as we call them sub-systems. Generally speaking, modularity and system decomposition is expected to result the following benefits: simplification (Decomposing large systems into smaller ones will lead to a reduction in the size of the problem that needs to be solve, which will make it easier to manage) and speed (solving smaller problems concurrently will reduce the time needed to solve the overall problem). [Kamrani and Salhieh, 2002] 

Modularity is based on the idea of interdependence within and independence across modules. [Baldwin and Clark, 2000] The previous chapters were focusing on the idea of independence across the system and this last one, on the interdependence within the whole system. In typical modular design, the interfaces indicate how the element interacts with the larger system.

More specifically, the whole design system of the course (the sustainable design of Texel Island) is divided into eight different sub-systems and specialized groups are working at each one separately and independently. These sub-systems are: Food & More, Health & Happiness, Leisure & Knowledge, Material & Waste, Public Space, Sustainable Mobility, Texel as host and finally our sub-system, which is Water Cycle.

It is consider possible to develop a fully sustainable water cycle sub-system, however water is just one sub-system of the true holistic urban concept, and although it is designing independently from the other sub-systems, it still corporate with them (more or less) creating an integrated whole. As it is mentioned above, all sub-systems are characterized by synergy and interdependence. Water Cycle management is closely linked with the whole urban development and consequently almost with all the other sub-systems.

A lot of economic activities in a city are dependent on a reliable supply of water. But there are also other examples of urban sectors such as energy, waste, health, transport etc. that are influenced by, and have an influence on, the successful management of water in a more or less obvious way.

The most efficient way to explain the relation between water cycle sub-system and the others sub-systems is by referring examples.

- Building Environment: The existing building environment influence the water consumption but also construction of new building developments creates additional water demand and the need for new distribution infrastructure.

- Health & Happiness: A reliable water supply of sufficient quality and quantity is essential for the health of a city’s population.

- Public Space: Land uses such as parks and gardens rely on large quantities of fresh water for irrigation.

- Host: Tourist destinations, like Texel, can experience huge peaks in water demand during the high season. Water supplies need to be able to cope during these peak periods if hotels and other facilities are to remain operational.

- Energy: Hydropower generation. 

- Materials & Waste: Poorly managed urban waste can cause the pollution of ground and surface water sources that a city’s water supply may be reliant on.

- Mobility: Most distribution pipelines run underneath roads and pavements. Rehabilitation of the network and the fixing of leaks cause disruption to the flow of traffic.

- Food & More:

- Leisure & Knowledge:

In this chapter, we tried to integrate the many sub-systems designs into a well-designed system because in the modular design, although the smaller subsystems that can be designed independently, they have to function together as a whole.

Kamrani, A. and Salhieh, S. (2002) Product Design for Modularity. USA: Kluwer Academic Publishers.

Baldwin, C.Y. and Clark K.B. (2000) Design Rules.Volum1: The Power of Modularity. London: The MIT Press        

After a few days on the island, where we were able to discuss our plans with interested locals and the people at the treatment facility, we are now able to evaluate our proposals.

A lot of our research has been confirmed: Fresh water is imported from the mainland, distributed over the island and recollected in the sewage systems all leading to the treatment plant we visited. The treated water then is released to the system of ditches, leading to the sea. Unfortunately this is still containing a lot of rainwater which is being treated unnecessarily. We did not realize however, that one of the biggest challenges concerning the water system is the enormous fluctuation in the demand. Since Texel its population doubles over summer there is a huge peak in the daily water consumption in that period.

We found out that until 1988 Texel used to be self-sufficient in their drinking water. A desalination installation, using excess heat from an energy-plant to distill sea-water, produced the drinking water during the seventies and eighties but with production costs of 7 guilders per cubic meter it was not economically feasible. Though all other Wadden islands produce their own drinking water, Texel, the biggest one is completely dependent on the pipelines. This is because the other islands are covered by more dunes. Texel only has one source, the Mokslootvallei, which has a capacity of 0,54 million cubic meters a year, one third of the demand.

With the current methods it isn’t economically feasible to have a separate drinking water treatment facility on Texel. Dutch drinking water is extremely cheap, around 1,76 euros a cubic meter, so in order to deliver water at that price a very efficient way of water production has to be found. On top of that it should be able to process enormous peak amounts in summer, making the installation even more expensive. For comparison, on the island Seba, which uses desalination, a cubic meter of drinking water costs 45 euros!

We found that the Hoogheemraadschap, who manages the waste water cleaning facility and the ground water level on Texel, already does great work. They make excessive use of natural methods and incorporate the water they clean in the total ecosystem. The biggest flaw we found is the fact that they do not separately collect rainwater so this is cleaned unnecessarily. We also think that, by implementing changes on a building level, a lot of water consumption can be prevented.

Therefore our final proposal focuses mainly on the reduction and re-use of the limited amount of fresh water on Texel. We want to offer packages that enable the inhabitants to reduce their water use and inspire the community to use and collect the rainwater. We will start on a personal level; awareness will be created amongst the inhabitants to motivate them to reduce their water consumption. There will be a basic package which will enable the Tesselaars to make small adaptations to their house, it will cost 70 euros and lead to a reduction of 20%. The next step will be to improve the water system on a building level. The advanced package will provide a new or renovated house with the best (future) water saving systems like modern toilets and rainwater harvesting systems. The final improvements should be applied on an island level, rainwater should be collected separately so it can be used and to prevent the unnecessary cleaning of it.

Though our initial plan was to close the loop and recycle the fresh water available on the island, we experience that, with the current technologies, this will not be feasible. Since building a new big machine will be too expensive and probably won’t improve the sustainability of the island, our future goal will not be self-sufficiency. By declining the water use on the island, as an example for the rest of the Netherlands, the amount of water that needs to be processed can be decreased drastically. If the demand is declined, the future innovators of Texel should be able to come up with a solution in the near future to make the island independent of the pipeline after all.