Unlike many hotter, drier parts of the world, here in the UK we are largely strangers to using non-potable water at home or at work. There are exceptions — some small-scale rainwater harvesting or grey water reuse systems, even some industrial non-potable use — but you have to be very keen or very desperate to forge a path off the beaten track.
While we remain a long way off being enthusiastic as a country, there is a distinct shift in thinking about the role non-potable water might play in helping to mitigate serious water supply gaps going forward. Both the UK Government’s Water White Paper and the Welsh Government’s Water Green Paper included commitments to look at ways to drive this. Harnessing locally sourced, non-mains water is increasingly being seen as a rational response to water scarcity, population growth and climate change, and an enabler of business resilience and growth. The illogic of using the 1 per cent of water on Earth that is drinkable for flushing loos, cleaning cars or cooling data centres is undeniable.
Drivers and obstacles
Any non-household customer considering non-potable use would need to weigh the pros against the cons. Business drivers include: necessity where potable water is not available in sufficient quantity; business continuity as a water security and resilience tool; cost as water tariffs increase over time; and ESG/sustainability reporting, as water is likely to move into greater focus.
Business obstacles include: slow payback for capital investment — non-potable systems are rarely cost-beneficial while mains water remains affordably priced; business cashflow disruption; the need for backup systems; safety risks around misconnection and cross-contamination; lack of operational expertise; and legislative, regulatory and planning issues that collectively make non-potable water systems difficult to plan, permit and operate. In the vast majority of instances, the obstacles weigh far more heavily.
Policy levers
Mandating action in defined circumstances would be the most sure-fire way to bring change. This could be through mandatory minimum standards for non-potable water use in new large commercial, industrial and public sector developments — embedded in planning policy and building regulations, rather than left to voluntary commitment. A lighter touch approach might be to mandate water efficiency audits for large users, analogous to energy audits under ESOS, with non-potable assessment as a required component.
There may be more appetite for policy changes that support water companies to invest in and operate communal non-potable networks. The current regulatory system was designed almost entirely around the supply of potable water and the removal of wastewater, not around differentiated water qualities or circular reuse. The Water Industry Act 1991 is ambiguous on the ownership and operation of non-potable distribution networks, particularly those that serve multiple customers.
Investment and other levers
Alone, it is unlikely that tariffs could be changed substantially enough to make investment in non-potable systems pay off, without other means of financial support. Capital provision of some sort would be needed in many cases — potentially through government grants, government incentives, water company incentives or tax reliefs — to improve payback periods and unlock investment.
Green finance standards could also explicitly recognise non-potable infrastructure as eligible for sustainable finance instruments, making it easier for businesses to access preferential lending.
Which water, where?
Different sources of non-potable water need to be matched carefully to end use, rather than treated as interchangeable. Rainwater and harvested surface water are generally the most straightforward and lowest-risk sources, particularly for non-contact uses such as irrigation, construction, wash-down and toilet flushing. Grey water (from sinks etc.) has a logical use within buildings, especially for flushing and cooling, but clear treatment standards and robust management are necessary.
Recycled wastewater (treated effluent) is the most complex, but also the most strategic. Many regard it as essential for large-scale water resilience — especially for industrial cooling, energy generation and data centres — but public perception, regulatory complexity and liability concerns currently limit uptake.
In terms of where non-potable water might be used, it is best to think in terms of purposes rather than sectors — with cooling, cleaning, rinsing, toilet flushing and irrigation as obvious examples. Data centres present an urgent case, as cooling demand is growing rapidly with AI infrastructure expansion. Power generation using hydrogen and carbon capture will impose additional water demand of 860 million litres a day by 2050. Construction for dust suppression and concrete mixing uses is another natural fit.