Martin Shouler: Future Urban Water

Martin Shouler is the Global Environmental Services Engineering and Public Health Engineering Skills Leader at the international engineering consultancy Arup. Martin works on water and related projects across both Building Engineering and Infrastructure. Martin has extensive experience in the field of Water Engineering having been involved in a wide range of major projects, in design, research and consultancy across the world.  In addition, he is a member of British Standards Institution (BSI) committees responsible for a number of water sector standards and has been involved in the development many British and European standards. Martin recently completed work for the Water Resources Group 2030 on Managing Water in Scarce Environments. He is responsible for Arup’s partnership with WRc on the water innovation service – Venturi (www.venturiportal.com) helping to accelerate the adoption of novel solutions in the water sector.

During Martin's recent colloquium at the Water Innovation Research Centre's symposium on 19 January 2017, he reflected on the development of modern water systems in and around buildings and how they fit in the wider urban context. He also made the argument that we need to consider water in a more integrated manner and how we might look to nature for inspiration.  Please click here to download an abridged version of the presentation "Future Urban Water Challenges".

Towards an Integrated Approach to Water for Cities

Water plays an essential part in the life of our cities. It is required to provide our basic needs for drinking water and sanitation, for industry and commerce and plays an important part in our health and well-being. Water is both an enabler for allowing cities to work and can also present a risk in the form of flooding and drought. We are facing problems caused by both too little and too much water. As well as climate change, this is being exacerbated by population growth and urbanization. In addition, for many cities, existing urban water infrastructure is often at or approaching its maximum capacity.  In the ancient world, large cities begun to develop aqueducts and river-based sewerage systems to support their development. Growing understanding of waterborne diseases and the introduction of the water flushed closet led to the provision of a centralised water supply and wastewater treatment models which have served us well for over 100 years. As many of these ageing systems are now reaching capacity, new models for water systems are presenting themselves. There is a growing understanding of the need to deliver smarter, better, cheaper, more resilient and environmentally sensitive water and wastewater systems.

The increasing demand placed on our water infrastructure has meant traditional centralized infrastructure may not be adequate to satisfy our urban needs in an economic manner. Decentralization of water infrastructure has grown extensively as a viable solution including non-potable water from sources such as greywater, rainwater and stormwater harvesting where policies are trending towards a more rational use with integrated systems. In our congested cities, access to blue and green spaces, as well as contributing to the management and control of water, can provide multiple health benefits. These range from reduced exposure to pollution and high urban temperatures through to improved mental well-being and providing opportunities for recreational use and wildlife habitats. Integrating these spaces with transport routes provide safe and appealing cycling, walking and running routes to allow citizens to travel more simply.

Water for buildings
When considering water demand for cities, much of it is related to buildings. Adequate water supply and drainage systems are a necessity for the safeguarding of the health and hygiene of building users; if they fail there can be serious health and safety consequences. The design of our water systems are rightly influenced by regulations, codes and standards. But regulations, codes and standards do not always keep pace with how water needs to be managed, the influence of changing demands and needs of citizens as well as climate change. We need up-to-date data and decision support tools.
 
The need for robust data to drive engineering
Much of the design data underpinning these codes was collated in the 1970s. However, water appliances and patterns of use have changed dramatically since then. New water appliances have appeared and others have become more efficient. If the codes are followed, it is likely that hot and cold water systems will be oversized (and therefore not as economical) which can also lead to other costs such as increased space take, increased energy and water use as well as lower throughput of water and the water quality issues that brings. Resource efficient building designs often incorporate water re-use systems such as rainwater harvesting, greywater and blackwater reuse, alongside standard drinking water provision. Hot and cold water distribution systems need to be designed to operate safely and hygienically with a range of demands placed upon them. Hot water temperature needs to be regulated to control bacterial growth whilst avoiding potential scalding.

Once buildings and their water systems are considered holistically with the infrastructure that serve them, we are able to apply new thinking to find ways to enhance their overall resilience. Good modelling and robust data is required to provide evidence base to drive new solutions.

Looking forward: towards a circular economy for water
Nature provides us many clues as to how we should manage water in an integrated way. We are all familiar with the basic premise of the water cycle. However, much of our water man-made water systems are linear in nature: running from catchment basin through to use through to discharge and eventually to the sea. For many contexts, a linear model does not allow for optimisation. For example, a circular approach can allow for value to be extracted from a wastewater stream so that resource flows can be enhanced. Depending on the scale, perhaps a better approach is to circulate water in closed loops. In this model, water can reused, better maintaining its value. Closed loop systems can operate at the ‘unit’ (for example, process or building) scale, at development (or campus) scale or at the bigger ‘city’ scale.

Taking a systems approach, we are beginning to better understand the role that water plays in the ‘circular economy’.