Dishwasher leaking: what to do now

Dishwasher leaks are sneaky. Unlike a washing machine, a dishwasher is usually built in under the worktop with a kickboard in front. Water can spread under the units for a while before you see it. In a flat, by the time you notice, it may already be in the ceiling below.

What to do first

1. Stop the cycle if it is running, but only if you can reach the controls without standing in water.
2. Make the power safe. If water is near sockets or the plug behind the units, switch off the kitchen circuit at the consumer unit.
3. Close the water. The dishwasher usually has an isolation valve under the kitchen sink, on the cold or hot pipe. A small lever or a slotted screw, a quarter turn closes it. If you cannot find it, use the stop tap.
4. Remove the kickboard under the dishwasher and the units next to it. Mop up and let the floor dry.
5. Tell the flat below if you are in a flat, and ask them to check their ceiling.

The usual causes

Cause	Where you will see water	Fix
Loose or split inlet hose	Behind or under the machine, near the sink	Tighten or replace the hose
Loose waste connection	Under the sink, at the trap or waste spigot	Refit and clip the hose
Blocked sink waste	Sink fills when the dishwasher drains	Clear the sink waste
Blocked filter	Water at the front, poor draining	Clean the filter
Door seal	Front edge of the door	Clean or replace the seal
Internal fault	Underneath, mid cycle	Appliance repair

Under the sink is where most leaks start

Most dishwasher plumbing meets under the kitchen sink. The inlet hose connects to a valve on the water pipe. The waste hose connects to a spigot on the sink trap, often held with a jubilee clip. Over time these connections loosen with vibration, or the waste hose works free.

There is also a simple thing to check. When a new sink trap is fitted, the dishwasher spigot often has a blanking cap inside it. If the cap was not removed, or if the sink trap is partly blocked, the dishwasher cannot drain properly and water comes back.

Galley kitchens over someone else’s room

In Camden, 26.2% of households live in converted houses, the highest share of the inner London areas we cover, according to the 2021 Census (Nomis, TS044). In Kentish Town and Camden Town conversions, kitchens were often squeezed into a back room or a narrow galley when the house was split. The kitchen in the upper flat may sit over a bedroom or bathroom in the flat below, with old timber boards in between.

A dishwasher leak that spreads under the units runs straight into that floor void. The first sign may be a stain on your neighbour’s ceiling, not anything on your floor. If you have had any leak, ask them to look.

Hard water and dishwashers

Thames Water says all the water in its region is hard. Dishwashers in London need salt topped up to soften the water they use. Scale still builds up on valves and in the waste, and a scaled isolation valve may leak or stick. If yours is crusty or stiff, have it replaced before it fails.

Who is responsible

The Leasehold Advisory Service says each leaseholder is usually responsible for their own appliances, such as washing machines and dishwashers. If your dishwasher damages the flat below, it is generally for you and your insurer.

If you rent, section 11 of the Landlord and Tenant Act 1985 requires your landlord to keep the installations for water and sanitation in repair. That covers the pipes, valves and sink waste, but not the dishwasher itself unless your tenancy agreement says so. Shelter notes that appliances such as washing machines are only the landlord’s to repair if the tenancy says so.

When to call a plumber

Call a plumber if:

• the leak is at the valve, the pipework or the sink waste
• water has gone under the units or into the floor
• the flat below has a stain or drip
• you cannot shut the water off at the isolation valve

Our leaking appliance and flooded kitchen page explains what a visit involves. If the leak is from the machine itself, such as the pump or an internal hose, you need an appliance repair. For washing machines, see our guide to a washing machine leaking from the bottom.

Preventing the next one

Check the hoses and the connections under the sink once a year. Make sure the waste hose is clipped firmly. Close the isolation valve when you go away. A small leak alarm under the sink or behind the kickboard costs very little and can warn you before water reaches the ceiling below.