Fixing common plumbing leaks around the home

Few things are as irritating as a tap that drips in the night, or as worrying as a damp patch spreading across a ceiling. The good news is that many common plumbing leaks around the home can be traced, isolated and fixed with basic tools and a little patience. The trick is to act early, before a slow weep becomes a soaked floorboard or a stained wall.

Know your stopcock and isolation valves

Before reaching for a spanner, find your stopcock and any isolation valves. Knowing how to shut the water off quickly is the single most useful DIY plumbing skill. Your internal stopcock is usually under the kitchen sink, in a downstairs cloakroom, or near the front door. Turn it clockwise to shut off the mains supply, then open a cold tap to confirm the water has stopped.

Many modern taps, toilets and appliances have small isolation valves on the pipework, letting you shut off one fixture without draining the whole house. If a valve will not turn, do not force it; use the main stopcock instead. Once the water is off, open the lowest tap in the house to drain down the pipes and reduce drips while you work.

Dripping taps: washers, cartridges and seals

A tap that drips from the spout usually has a worn washer or a failing ceramic cartridge. On a traditional tap, turn off the water, unscrew the head, and remove the jumper or washer assembly. Take the old washer to a hardware shop and match it exactly. Reassemble carefully and do not overtighten, as this can damage the seat.

Ceramic disc taps need a replacement cartridge rather than a washer. Note the make and model if you can, or take the old cartridge with you. If the drip appears at the base of the tap instead of the spout, the gland packing or an O-ring may have failed. A few wraps of PTFE tape around the spindle threads can cure a minor weep, but if the tap body is corroded, replacement is the safer long-term fix.

Leaks under sinks and at compression joints

The area under a kitchen or bathroom sink is a prime suspect for hidden leaks. Compression joints, which use a nut and a brass olive to grip the pipe, can weep after years of expansion and contraction. Turn off the water, dry the joint completely, and tighten the nut by a quarter turn with an adjustable spanner. If it still drips, undo the joint, inspect the olive for crushing or scoring, and replace it if necessary.

Push-fit fittings are common on plastic pipework. A leak here usually means the pipe is not inserted fully or the O-ring is damaged. Isolate the supply, remove the fitting, check the pipe end for burrs, and push it home firmly. Waste traps are another common source. Hand-tighten plastic nuts, check the rubber washers are seated correctly, and reseal with silicone if the joint is stubborn. Never use excessive force on plastic, as it cracks easily.

Toilet cistern and overflow leaks

A toilet that constantly trickles into the pan is wasting water and often points to a worn flush valve seal or a misadjusted float valve. Isolate the supply, flush to empty the cistern, and replace the flush valve washer or the whole siphon unit. If the overflow pipe drips, the float valve is not shutting off properly; clean or replace the diaphragm washer inside it.

Leaks at the base of the cistern often come from perished rubber washers on the tank bolts. Tighten the bolts evenly, but only a little, as overtightening can crack the ceramic. If water appears at the floor around the pan, the pan connector or soil pipe seal may have failed. This is a job where a plumber is often worth calling, especially if the leak is behind tiles or under a sealed floor.

Radiator valves and appliance hoses

A dripping radiator valve is usually a worn gland. Place a cloth underneath, then tighten the gland nut a quarter turn. If the drip continues, the valve may need repacking with PTFE tape or replacing altogether. Heating system water is often dark and dirty, so a leak can leave unsightly stains on carpets and walls. Catch it early and check the pressure gauge on your boiler afterwards.

Washing machine and dishwasher hoses are frequent culprits because they are under constant pressure. Check the connection at both ends, replace the rubber washers if they are flattened, and replace the hose every five years as a precaution. Flexible tap connectors under sinks can also burst without warning. If you see bulging or corrosion, replace them before they fail.

Shower, bath and waste pipe leaks

Shower leaks often appear as a damp patch on the ceiling below. Check the silicone seal around the tray first, then inspect the waste trap and the shower valve connections. Remove old silicone completely, clean the surfaces, and apply a fresh bead of sanitary silicone. Bath waste and overflow fittings can also weep; tighten the back nut and renew the rubber washer if it has hardened.

Waste pipes under baths and showers are usually push-fit or compression. A slight drip can be cured by tightening the joint or replacing the rubber seal. If you notice a stain on a ceiling, stop using the fixture immediately. Water travels along joists, so the visible damage may be some distance from the actual leak. Take photographs for any insurance claim, and do not ignore a slow drip. Small repairs now are far cheaper than replacing a ceiling, floor or boiler.