The most common causes of water damage at home

Most water damage at home does not start with a burst pipe. It starts with a hose that has gone brittle, sealant that has come away or a fitting that drips a little at a time. The fault is small. The damage gets big because nobody sees it.

Insurers call it escape of water, and it is one of the most common home insurance claims in the UK. Here we walk through the usual causes of water damage, room by room: why each happens, the warning signs and how to prevent it.

The kitchen: dishwasher, tap and fridge

The kitchen is often mentioned as one of the most common places for water damage at home. It packs several connections into a small space, almost all hidden behind doors and plinths.

The dishwasher. The inlet hose is under pressure around the clock. Rubber and plastic age, and hoses get pinched every time the machine is pulled out and pushed back. Watch for a swollen kickboard and soft or discoloured flooring in front of it. Pull it out once a year to check the hoses and floor. A drip tray underneath makes a leak visible instead of letting it soak into the floor.

The mixer tap and the connections under the sink. Most kitchen taps are connected with flexible hoses that can corrode, split or loosen, and the trap can start to drip. Signs are a damp cupboard base and swollen chipboard. Keep the cupboard clear enough to see the bottom, and feel the hoses whenever you reach in.

Fridges with an ice maker or water dispenser. A thin plastic pipe feeds the fridge, often run behind the units. It can kink when the fridge is pushed back, and the connection can work loose. Look for water under the fridge and swollen flooring around its feet.

The utility room and airing cupboard

The washing machine. It has a pressurised inlet hose and a waste hose that can slip out of the standpipe. On a fast spin the machine can walk and pull on its hoses. Signs are water on the floor after a wash and corrosion on the isolation valve. Turn the valve off when you go away and keep the machine level.

The hot water cylinder. A cylinder holds a lot of water and has several joints. An unvented cylinder also has a pressure relief valve whose discharge should run safely to a drain. Problems start when the valve sticks, the discharge pipe is badly routed or an old cylinder corrodes. Look for rust or white deposits around the fittings. Have it serviced as the manufacturer recommends, and plan a replacement if an older one shows rust.

The bathroom and the toilet

Failed waterproofing behind the tiles. Tiles and grout are not waterproof. The tanking or membrane behind them is what keeps water out of walls and floors, and over the years it can crack around pipes, in corners and at the shower tray. Older bathrooms may have none at all. Signs are hollow sounding tiles, stained grout and damp patches on the other side of the wall or the ceiling below.

Sealant and the shower. Silicone around the bath and shower tray wears and pulls away, and the connections to a shower valve in the wall can weep. Cut out and replace sealant as soon as it lifts or turns black.

Wet room drains and shower trays. A wet room drain must be sealed to the membrane. If that seal fails, water runs down beside the drain instead of into it. Keep drains clean and reseal when gaps appear.

The toilet cistern and fill valve. The fill valve should shut once the cistern is full. When it wears, water trickles into the pan or out of the overflow all the time. Listen for a faint trickle, check for damp around the base and replace worn valves and washers.

The pipes: frost, age and outside taps

Frozen pipes in cold spaces. Water expands as it freezes and can split a pipe, most often in lofts, garages, under suspended floors and along outside walls. The damage often only shows when it thaws. An early sign is a tap that gives little or no water on a cold morning. Lag the pipes and keep a little heat in the space. Our guide on how to stop pipes freezing goes into more detail.

Ageing pipes and joints in older houses. Copper can develop pinhole corrosion, galvanised steel rusts from the inside and very old houses may still have lead. Joints age too, mostly out of sight in walls and floors. Signs are green or rusty marks at fittings and damp patches with no obvious cause. If the plumbing is original in an older house, ask a plumber to assess it.

Outside taps. Water left in the tap and its pipe can freeze and split, sometimes inside the wall, and you may only notice in spring. Before the first frost, turn off the isolation valve indoors, open the outside tap to drain it, remove the hose and fit an insulated cover.

What these causes have in common

Almost every cause here starts small and out of sight. A few drops an hour behind a kickboard. A little water through the sealant with every shower. There is no alarm, so the damp spreads through floors, joists and insulation before anyone notices.

That is why prevention is mostly about time. Time, not the size of the leak, drives the cost of a water leak. Hoses, washers, sealant and valves all give up eventually. You cannot make them last for ever, but you can notice when they start to fail.

A quick checklist for a drier home

• Pull out the dishwasher, washing machine and fridge once a year and check hoses and floor.
• Keep the cupboard under the sink clear enough to see the bottom.
• Turn off the washing machine valve when you go away.
• Have the hot water cylinder serviced.
• Replace failed sealant and keep shower drains clean.
• Listen for a toilet that keeps trickling.
• Lag pipes in cold spaces and drain the outside tap before the frost.
• Know where your stopcock is and make sure it turns.
• If you have a water meter, read it when nobody is using water. If it moves, water is going somewhere.

How to catch many leaks early

Checks help, but only on the day you do them. A leak that starts the next day can run unnoticed for months.

A more reliable approach is to measure the flow on the incoming mains water pipe, where water enters the house. When nobody is using water, the flow should be zero. A dripping fitting, a trickling cistern and a pinhole in a hidden pipe all show up as a small but constant flow.

Water Grip works this way. You can fit it yourself in a few minutes without a plumber. It measures the flow continuously and sends an alert to the app when something looks abnormal, wherever you are. You then turn off the stopcock or ask someone else to. Water Grip also has a freeze warning that alerts you when the pipe where it is mounted reaches 4°C.

Not everything is caught this way. Failed waterproofing that lets shower water into the wall does not show up as abnormal flow, because the water is being used as normal. But many of the most common causes of water damage do exactly that: they leak a little, all the time. That is when it pays to have something watching.