Overflow pipe dripping water outside

In the UK, an overflowing discharge pipe from the outside wall indicates that either a toilet cistern, cold water storage tank (loft), or hot water cylinder (indirect models) has a fill valve that is not shutting off properly.

Identify which overflow it is: toilet cistern (small pipe, usually at the back of the toilet or through the wall near cistern height), cold water storage tank (large pipe exiting high up through the eaves), or cylinder (overflow exits near the cylinder height).

For a toilet cistern overflow: remove the cistern lid and check the water level. If it is above the overflow outlet, the fill valve (ballcock) is not shutting off. Try bending the float arm downward, or replace the fill valve (£8–£20).

For a loft tank overflow: go into the loft and find the cold water storage tank. The ball valve arm may have jammed up, or the float may have sunk. Replace the washer or ball valve (£5–£15).

For a hot water cylinder overflow: if the indirect cylinder's temperature relief or cold feed ballvalve is discharging, call a plumber — this can indicate overheating or pressure issues.