The Future Homes Standard aims to improve energy efficiency within new housing when details are published this autumn. Ben Standing, partner in planning and environment at law firm Browne Jacobson, argues it must include grey water recycling
While solar panels, heat pumps and new insulation techniques are rightly front and centre of the discussion regarding new housing standards, less prominence is given to grey water systems. Given that demand for water is likely to outstrip supply in Britain over the next 25 years, this must change.
The Future Homes Standard presents the ideal opportunity to ensure new grey water is integrated into sustainable housing designs when it’s published by the Department for Energy Security and Net Zero this autumn.
What is grey water?
The World Health Organisation (WHO) categorises domestic wastewater into two categories – black water, which originates from toilets and kitchens and is contaminated, and grey water, which is untreated household wastewater that has not been contaminated by toilet waste.
It states that grey water includes water from baths, showers, bathroom sinks, and washing machines. This doesn’t include waste from kitchen sinks, garbage disposal units, or dishwashers. Grey water accounts for up to 60% of the wastewater discharged into sewers, according to the WHO.
Recycling systems work by collecting wastewater from appliances and directing it into a collection unit, where contaminants are removed.
The wastewater is then treated to prevent bacteria from passing through the system, before being pumped out to be reused for toilet flushing, garden irrigation and washing machines.
Examples of grey water systems in new homes include:
- Dual-pipe systems that separate potable and non-potable water supplies.
- Pre-plumbed greywater systems, which are prevalent in modular or prefabricated builds.
- Smart metering and water-efficient fittings that monitor and reduce consumption.
While grey water isn’t safe to drink, it can reduce water consumption by up to 40% and lower carbon emissions from heating water, while also supporting biodiversity through sustainable landscaping.
The WHO states: “Greywater reuse utilises an on-site resource which would otherwise be wasted. As a result of reuse, fresh drinking-water supplies are conserved, which in turn enables the water to remain in natural ecosystems.
Grey water reduces public demand on potable water supplies and sewage flows. This prolongs the life of waste water disposal systems and saves costs for water authorities that are passed on to consumers.
However, its reuse doesn’t come without challenges, including gaining public trust amid concerns about health risks and reliability of systems, which need regular upkeep to ensure safety and performance.
There are also regulatory and policy hurdles as these either prohibit or ignore grey water integration within homes.
Integrating grey water recycling into the Future Homes Standard
Despite their clear environmental benefits, there’s currently no explicit mandate for grey water systems within the Future Homes Standard.
There remains time for this to change, however.
Announced under Theresa May’s government in the 2019 Spring Statement, the new standard was expected to be implemented by 2025, with an ambition for new homes to produce 75% to 80% fewer carbon emissions than under existing building regulations.
It aims to achieve decarbonisation by focusing on improvements to heating and hot water systems, as well as reducing heat waste through better insulation.
Little detail has followed since then, but there was finally an update this summer when the Labour government confirmed the full Future Homes Standard will finally be published this autumn. It is reportedly scheduled to be implemented by the end of 2027, two years later than originally planned.
Water efficiency is a feature in some existing regulations. Building Regulations Part G sets minimum standards, for example, but is considered outdated. In contrast, Regulation 20 of the Environmental Targets (Water) (England) Regulations 2023 sets a target to reduce the volume of potable water supplied per person by at least 20% by 2038.
In some water-stressed areas, including Sussex North and Greater Cambridge, developers must also demonstrate no net increase in water use. To achieve this, they’ll often deploy on-site grey water reuse, rainwater harvesting and offsetting via retrofitting nearby properties.
A regulatory hurdle facing grey water integration, however, is the Drinking Water Inspectorate Regulations, which restrict the use of non-potable water supplies in homes for public safety.
Addressing water supply challenges
Often absent from the discussion on climate resilience is access to water. Yet, analysis by the Environment Agency’s (EA) National Framework for Water Resources, published in June this year, estimated England’s public water supply could be short by five billion litres a day by 2055 without urgent action to futureproof resources.
A further one billion litres a day will also be needed to generate energy, grow our food, and power emerging technologies.
The EA expects 60% of this deficit to be addressed by water companies managing demand and dramatically reducing leaks.
However, the remaining 40% requires boosting supply, including the building of new reservoirs and water transfer schemes.
New water infrastructure is vital, but it also comes with its own challenges, including identifying suitable sites, planning constraints, and costs.
Therefore, just as we need to complement new renewable energy infrastructure with enhanced measures to conserve energy usage within homes, the same applies to water.
Similar to efforts that aim to integrate green housing features into overall high-quality design, we must also consider how building standards address water scarcity. An excellent starting point would be to ensure grey water recycling systems are integrated into new-build homes.
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