The Department for Environment, Food & Rural Affairs (Defra) has published updated guidance on water fittings regulations specifications, effective from 6 May 2027. The guidance sets out regulator-approved specifications for compliance with the Water Supply (Water Fittings) Regulations 1999, SI 1999/1148in England and Wales, which are intended to prevent contamination of the public water supply, ensure efficient water use, and protect against misuse and waste, with enforcement carried out by water undertakers. Defra states that approved water fitting specifications, including certain Test Code Sheets (TCS), provide a recognised means of demonstrating compliance and confirms that the specifications published on the Water Regs UK website apply in their current form. The updated specifications relate to backflow prevention, water closet suite performance, flush rate, dimensional requirements, overflow compatibility and related testing, including a new specification, TCS 2213-20 on dimensional and internal overflow compatibility, while specification TCS 5011-5 on measurement of dimension will cease to apply from the same date.