Demand for water will outstrip supply within the next 25 years in England. Changing patterns of water use – for example, as a result of increasing hygiene standards –  are intersecting with long-standing infrastructural challenges of ageing water and sewerage networks. In this article, Dr Ella Foggitt, Dr Claire Hoolohan and Professor Alison Browne assess how infrastructural issues, exacerbated by climate change are resulting in immediate and substantial challenges to public water supplies.

• England could face a water supply gap of over 4.8 billion litres per day by 2050.
• New options are needed to supplement the 14 billion litres per day currently delivered by water companies. It is anticipated that demand management will contribute 65% of activity needed to resolve the forecast deficit, particularly in the next 10-15 years.
• Demand management involves improving the efficiency of water supply and changing the way that water is used.

The role of housing developments in water supply

New housing developments present multiple opportunities to foster more sustainable ways of living and help reduce water demand. The Enabling Water Smart Communities project (a collaborative project bringing together UK water utilities, innovators in the built environment, leading academics and industry bodies) explores opportunities for integrated water management to contribute to solving problems in water systems.

To realise these opportunities, focus needs to shift away from individual residents to instead recognising the various ways that water use is embedded in the design of homes and communities. The importance of retrofitting existing housing stock notwithstanding, new build homes present an opportunity to set more ambitious water use targets to improve water efficiency and reduce demand.

The UK government is already exploring how to reduce water scarcity. However, today’s building standards are insufficient to mitigate climate change or manage water scarcity. While proposals to revise building regulations are being considered, more can be done by exploring the potential for water reuse.

Current emphasis is placed on fixtures and fittings – the materials that supply and affect the flow of water in homes and gardens. Important conversations about how a fixtures and fittings approach can radically reduce water use, particularly in new build homes, are ongoing. However, issues around how to ensure water-efficient appliances are installed in new homes, how they are used over time, whether assumptions made about their use hold up, and how water reductions will be maintained as appliances break down or reach the end of their design-life, need to be considered.

Fit-for-purpose water supply systems

Looking beyond fixtures and fittings, water reuse options that offer potential for fit-for-purpose supply at the development scale, present further opportunities. Water reuse could enable wider changes by altering how people interact with water in their homes, communities and the natural environment. Development-scale water reuse is where rainwater and greywater (e.g. wastewater from showers and sinks) are captured and reused in housing developments for practices such as toilet flushing.

The relationship between residential water reuse and overall water demand is understudied, but there is evidence that suggests it could help to reduce potable water demand. Research also shows that the degree of support for water reuse depends on its end-use (whether for gardening, toilet flushing, washing clothes/bodies, or drinking/cooking).

With this evidence, water reuse offers a potential fit-for-purpose water supply via a dual-pipe system, allowing some needs such as drinking, to be met through a potable system, and other practices such as irrigating gardens, clothes washing and toilet flushing, using a reuse system. Thus, water reuse could reduce potable water demand associated with specific practices while continuing to deliver on public health objectives. Research in Australia showed the importance of understanding community definitions of risk – with trust in the management of these infrastructures and technologies more important for risk perception than the ‘yuck factor’ of water reuse.

Greater attention and investment in social science research is needed to expand this knowledge base, including on the effect of water reuse and reconfigured water supply systems, such as dual pipe systems, on overall water demand.

Current challenges to water reuse systems

There is also a need for critical attention on how policy developments in other areas affect everyday life, and therefore change patterns of water use in new developments. New homes and communities must deliver on a range of environmental objectives – from biodiversity to climate change mitigation.

Shifts towards active travel and remote working practices have uncertain implications for water demand. Careful consideration of how the design of infrastructures within new developments shape future ways of living with water, and balancing changes in consumption through fit-for-purpose supplies – both have roles to play here. Meanwhile, wastewater policy issues could impact public perceptions of water companies’ ability to safely govern water reuse, with evidence showing that public support of water reuse is closely linked to trust in the water authorities. Overall, there is limited evidence on community perspectives of water reuse systems, particularly in the UK. The Enabling Water Smart Communities project is working to address this gap, exploring the potential for mains-limited developments in England with professionals and publics.

Perceived health risks can also challenge the feasibility of new water reuse schemes as they can lead to highly cautious risk reduction measures – which come with high operating costs. Another substantial issue is the Drinking Water Inspectorate regulations, which state that water supplied to residential properties needs to be ‘wholesome.’ Current interpretations of this regulation mean that only potable water can be supplied to residential properties, irrespective of the use. Thus, current understandings of Regulation 4 (Wholesomeness) of the Water Supply (Water Quality) Regulations 2016 (England) and 2018 (Wales) limit ambition of water reuse. A review of this legislation could help ensure that these regulations protect public health while creating a space for innovations to reduce water demand.

Monitoring, reviewing and collaborating for sustainable water infrastructure

To ensure ongoing resilience and sustainability of water infrastructure systems, there is a need to review water regulations to ensure the protection of public health while also creating space to trial new models of water provision, such as water reuse, that lessen environmental impacts.

There is a need for robust, long-term and transparent monitoring by regulatory agencies to ensure that building standards are adhered to, and that the anticipated savings are realised once homes are lived in. Collating and sharing information on the target water consumption per capita versus the actual per capita consumption once homes are built, as well as measures taken to achieve the target, would all be useful, along with building regulations to guide this.

Better understanding is needed to identify effective models for the ownership, governance, use and maintenance of such infrastructures. Here, evidence from dual water delivery systems in other global contexts could be useful.

Rethinking roles within and between communities with collaboration between local authorities and government bodies could be one route to fostering long-term resilience and sustainability. Ensuring that homes, amenities and infrastructures in new developments contribute to tackling societal and other problems we will face in the future, requires us to critically reflect on whether current designs of homes and communities enable or restrict more resilient ways of using water.