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