A plain-English tour of the areas Part G of the Building Regulations guides, from cold water to scald safety.
Approved Document G provides guidance for meeting Part G of the Building Regulations in England. It covers cold water, water efficiency, hot water safety and sanitary facilities. The regulations set the requirements; the approved document describes ways to meet them.
G1: match water quality to the outlet
Drinking-water outlets and food-preparation sinks require wholesome water. The specified washbasins, bidets, baths and showers may receive wholesome or softened wholesome water.
WC and urinal flushing have a separate requirement: water of suitable quality. A properly designed alternative supply can serve flushing. It does not follow that reclaimed water can supply the bathroom washbasin or kitchen sink.
Worked decision: a new dwelling has wholesome water at its kitchen sink, but the washbasin is connected to a non-potable rainwater system. The kitchen supply alone does not meet the requirement for the washbasin. Trace each outlet's use and supply; do not judge the entire dwelling from one tap.
The wholesome supply also has to arrive at enough pressure and flow to operate the fittings, not merely be clean: a working installation needs both quality and a reliable, adequate delivery.
A direct cold-water system supplies the cold outlets from the main. A common indirect arrangement leaves the kitchen drinking tap on the main and feeds other outlets from a storage cistern. Trace the actual connections, since houses can have mixed arrangements. The stored reserve supplies its connected outlets during a short mains interruption; the available gravity pressure depends on the water surface’s height above them.
G2 and G3
G2 concerns water efficiency in new dwellings. Choose suitable fittings and assess expected consumption; slowing a refill valve is not the same as reducing flush volume.
G3 concerns hot water provision and safety, including stored-water controls, safe discharge and scald protection. A drinking-quality supply does not by itself establish that a hot water installation is safe.
G4–G6 cover sanitary conveniences and washing facilities, bathrooms and food-preparation areas. These headings help locate the relevant requirement; they are not a substitute for checking the detail of a proposed installation.
Efficient fittings matter for more than the water itself: at a hot outlet, using less water also means less has to be heated, so water efficiency reduces wasted wholesome water and the energy spent warming it together.