The UK's largest water reuse system, built into the Eddington development on the edge of Cambridge, has never been switched on since it was completed in 2021 because the Drinking Water Inspectorate has ruled it does not comply with drinking water regulations. The scheme could save thousands of residents around 25 litres of water per person per day by recycling rainwater for non-drinking purposes, but it remains locked down even as Cambridgeshire, one of England's driest regions, endures drought conditions and hosepipe bans imposed by Cambridge Water and Anglian Water. Campaigners say the legal block, which ministers in successive governments have known about but failed to resolve, is also preventing water companies from rolling out similar large-scale recycling schemes elsewhere at a time when experts warn England faces severe water shortages by 2055.

Eddington, developed by the University of Cambridge, will eventually house 8,000 people and uses swales to capture rainwater, feeding it into a lagoon that also protects nearby brooks from flooding. Cambridge Water designed a treatment system to recycle this water back into homes for toilet flushing and similar uses, but the Drinking Water Inspectorate deems the setup unlawful. Lutz Johnen, chair of the UK Water Reuse Association, called for urgent government action, noting that countries such as Belgium and Germany have run reuse systems for over 20 years, with Belgian households using around 90 litres of mains water per person daily compared with 140 litres in England and Wales.