Wastewater treatment ponds. Credit: Philip Songa.

+ We need to consider the urban water cycle as a whole – we need integrated water management.

Cities worldwide are facing problems caused by both too little and too much water. Urbanisation and climate change are making things worse. And water infrastructure in many cities is approaching its maximum capacity. How should we respond?

We need to consider the urban water cycle as a whole. We need integrated water management. This means optimising grey (traditional piped water and wastewater services), green (green roofs and parks) and blue (rivers and water bodies) infrastructure to provide the widest possible community benefits.

In my experience, there are six key issues we need to consider for a successful integrated water management approach: 

1. Understand the context and constraints – water is a local issue so a solution that would work well in London may not be suitable for Mumbai.

2. Have a clear vision of what the scheme needs to achieve, including wider benefits such as health and wellbeing.

3. Get everyone involved around the table as soon as possible, including representatives of the local community and land use planners.

4. Model and communicate emerging designs and climate change risk effectively so everyone knows what is proposed.

5. Focus on the value of water and how it can benefit the local community.

6. Establish trust, an understanding of each other’s point of view and a sense that everyone is working together.

I think this helps ensure us arrive at the right solutions.

Take water reuse, for example. Cities as diverse as Perth, Los Angeles, Singapore and Windhoek are already reusing water. This is good news, but water solutions need to be assessed carefully. 

If we focus purely on one solution, such as water reuse, we may miss out on other appropriate solutions like water efficient fixtures and fittings. Green open spaces are another complementary solution with dual benefits; they can not only be irrigated by greywater but can also help to manage storm water and so reduce flood risk.

The technical solutions for this approach are relatively straightforward; the difficulty is that it requires many stakeholders to work together. But if we are to make best use of our precious water resources, we must do exactly that. 

It can be done. Arup is applying integrated water management techniques to London’s largest development at Nine Elms on the Southbank. Here, using a geographical information system to manage data and visualise water solutions is helping communicate the options to key stakeholders.

Other cities are doing the same. In New York, Arup is working with the city authorities on the NYC Green Infrastructure Program to reduce combined sewer overflows. This will also benefit neighbourhoods by reducing localised flooding, improving air quality and reducing the heat island effect. In Wales, we’ve worked with Dwr Cymru Welsh Water, Cardiff Council, Natural Resources Wales, as well as local residents and businesses, on a feasibility study for reusing surface water to green Grangetown’s existing streetscape and open spaces.  

I’m sure that if this integrated approach were followed more widely, we might just fix some of the problems the world faces from having both too much and too little water.