Washing machine leaking from underneath: find the source

Make it safe before you look

Water and electrics share the same small space behind a washing machine. Switch the machine off and unplug it before moving it or putting your hands near the connections. If water has reached the socket, the plug or an extension lead, switch off the circuit at the consumer unit and do not touch the plug until it is dry and checked.

Turn off the appliance supply valve, usually a small lever or slotted valve on the pipe behind the machine. If there is no valve, or it will not turn, use the main stop tap. Mop up so you can see fresh water appearing, and put a dry towel or tray down to help you trace the next drip.

In a flat, water under an appliance can travel under flooring and appear in the ceiling below before you see much on your own floor. If a neighbour reports a damp ceiling, treat it as an active leak and stop using the machine.

Use the timing of the leak to narrow it down

Different parts of the plumbing only carry water at certain points in a cycle. Watching when the puddle grows is the quickest way to separate a supply leak from a waste leak or an internal fault.

Supply leaks: the fill hose and valve

The fill hose screws onto a threaded valve on the cold supply, and sometimes a hot one on older installations. Each end has a rubber washer. These washers harden and flatten with age, and the connection then weeps under mains pressure. Hoses themselves can split near the fittings, especially after the machine has been pulled out and pushed back a few times.

A supply leak is the one to take most seriously, because it is under constant pressure and does not stop when the cycle ends. A braided hose that has started to bulge or fray should be replaced, not tightened. The valve can also leak from its spindle, or seize so that it cannot be used to isolate the machine in an emergency. Replacing a seized or weeping valve is a straightforward plumbing job and worth doing while the machine is already pulled out.

Waste leaks: hoses, standpipes and blocked pipes

When the machine pumps out, it pushes a fast surge of water through the waste hose into either a standpipe or a spigot on the sink waste. If the hose is not pushed far enough into the standpipe, or has been kinked behind the machine, water can splash back or overflow. A loose clip on a sink waste connection leaks only when the machine drains, which is why it is often missed.

If the waste pipe is partly blocked with lint, fat or detergent build-up, the machine can pump faster than the pipe can carry the water away. The standpipe overflows at the top, or water backs up into the kitchen sink. That is a drainage fault rather than a machine fault, and it usually gets worse over time. Our guide to washing machine water backing up into the sink covers that pattern in more detail.

When the machine itself is leaking

If the supply and waste connections are dry and the water still appears under the middle of the machine during a cycle, the leak is probably internal. Typical causes include the drain pump or its filter housing, internal hoses, the door seal and, less often, a cracked tub. Some machines have a small filter door at the front bottom; if that cap was not fully tightened after cleaning, it will leak on every drain.

Internal appliance faults are a job for the manufacturer or an appliance engineer. A plumber can still help by confirming that the supply valve, hoses, waste and trap are sound, so you are not paying for an appliance repair when the problem is the pipework behind it, or the other way round.

Check for hidden damage after a leak

A slow leak under a washing machine can run for weeks before anyone moves the machine. Water soaks into chipboard flooring, runs under kitchen units and can reach walls and ceilings below. Once the leak is fixed, check the floor for softness, lift a kick board to look under the units, and watch for musty smells or staining over the following days.

If you are not sure how far the water travelled, moisture readings and a methodical look under units give a clearer picture than guessing. Our guide to drying a home after a plumbing leak explains what to check before flooring or units are replaced.

Getting it fixed

Loyal Plumbers repairs appliance supply valves, hoses, waste connections and blocked kitchen waste pipes across London and inside the M25, and we run 10 vans around the clock for leaks that cannot wait. When you call or enquire, tell us when the water appears in the cycle, whether it is from the front, back or middle of the machine, and whether anything below has been affected.

If the supply valve has seized, the machine is in a flat above another property, or water is reaching electrics, call rather than send a form. We will isolate and repair the plumbing and tell you plainly if the remaining fault is inside the appliance.