Low mains water pressure throughout the house

Low mains pressure affects all outlets equally — if only some taps are affected, the problem is more likely a blockage or restriction in the internal pipework rather than the supply pressure. True low mains pressure means a noticeably weak flow from every tap including the kitchen cold (which is fed directly from the mains in most UK homes).

First check with your neighbours — if they also have low pressure, the issue is with the water company's supply main. Report it to your water supplier (Thames Water, Severn Trent, Yorkshire Water, etc.) who have a statutory obligation to maintain minimum supply pressure of 10m head (approximately 1 bar) at the boundary.

Check your main stopcock — usually under the kitchen sink or in a utility room. Ensure it is fully open (turn anti-clockwise fully). A partially closed stopcock is a surprisingly common cause of low pressure.

If the supply pipe is old lead or narrow bore (many pre-1970 properties have 15mm or even smaller service pipes), the flow capacity is restricted. The water company can sometimes upgrade the supply pipe from the street to your boundary for free; the portion from the boundary to your house is your responsibility (£500–£2,000 depending on length).

A booster pump (Stuart Turner, Grundfos) can be fitted on the incoming main to increase pressure throughout the house. A qualified plumber should install this — a typical system costs £300–£600 fitted and requires a check valve and pressure vessel to be installed correctly.

Ensure the pressure-reducing valve (if fitted) is not set too low. A PRV is often fitted by plumbers to reduce high mains pressure — if it has been set conservatively or has failed, it can reduce pressure below useful levels. A plumber can adjust or replace it.