Dehumidifier leaking water? Causes and fixes

First, make it safe

Switch the dehumidifier off at the wall and unplug it before you touch it. Mop up any water and make sure the plug, socket and cable are dry. If water has reached a socket or extension lead, leave it switched off and dry, and get an electrician to check it if you are in any doubt.

Move the unit onto a dry, level hard floor for the checks below.

Note:Never handle a plug or socket with wet hands, and do not switch back on until everything is dry.

Check the tank

The most common cause is a tank that is not pushed fully home. Remove it and refit it firmly. Most units have a float switch that stops the dehumidifier when the tank is full, and if the tank sits slightly out of place the float may not register while water drips past the edge.

Inspect the tank for cracks, especially at the corners and around any handle or cap. Hold it up to the light and fill it with a little water over a sink to see if it seeps. Cracked tanks are a common spare part, so check the maker's spares page.

1. 1

   Unplug and remove the tank

2. 2

   Empty and dry it

3. 3

   Look for cracks and test it over a sink

4. 4

   Check the float moves freely

5. 5

   Refit firmly until it clicks or sits flush

Check the drain outlet and hose

If the unit has a continuous drain outlet, it is usually sealed with a rubber bung or cap when you use the tank. If that bung is missing, loose or perished, water can run straight out of the back or bottom. Refit or replace it.

If you use a drain hose, check it slopes downhill all the way, has no kinks or loops, and is pushed fully onto the outlet. A hose that rises above the outlet will back up and overflow inside the unit. Our guide on how to drain a dehumidifier continuously covers the set-up.

Check for ice

In a cool room, a compressor dehumidifier's coil can ice over. When the unit defrosts or is switched off, that ice melts faster than the drip tray can cope with and water overflows. You may see frost on the coil behind the filter. Our guide on why a dehumidifier ices up explains the causes and fixes, which usually involve a warmer room, a cleaner filter or a desiccant unit for cold spaces.

A clogged filter also restricts airflow and makes icing more likely, so clean it as described in how to clean a dehumidifier.

Check it is level and not tilted

A dehumidifier that sits on a slope, a thick rug or an uneven floor may let the drip tray tip water over its edge. Put it on a level hard surface. If it has been carried on its side or tipped over, most manuals ask you to leave it upright for a period before switching on; check yours.

When it is an internal fault

If the tank is sound, the bung is in place, the hose is fine, there is no ice and the unit is level, water may be escaping from a blocked or cracked internal drip tray or a loose internal pipe. That needs a repair. Contact the maker or retailer, especially if it is under warranty, rather than opening the case. If an older unit keeps leaking, compare repair against a new model in our guide to the best dehumidifiers for UK homes.

Compare the best dehumidifiers for UK homes →

Frequently asked questions

Why is my dehumidifier leaking from the bottom? Usually a tank not seated properly, a cracked tank, a missing drain bung, or ice melting off the coil. Check those in turn.

Is it safe to use a leaking dehumidifier? No. Switch it off and unplug it until you have found the cause and everything is dry.

Why does water appear when I switch it off? Often ice on the coil melting. That points to a cold room or a clogged filter.