A washing machine filling with water overnight or when not in use has two possible causes. Either the water is running into the washing machine from the sink ( If the drain hose is connected directly to the u-bend under the sink
) or one of the water valves isn't shutting off properly and water is dripping slowly but surely into the washing machine. The latter problem can take several hours before the water level rises high enough inside the washing machine to be visible.
It's easy to track down the cause of water entering the washing machine when not in use. If turning off the hot and cold water taps stops it, then it's one of the water valves not shutting off properly, and needs replacing. It's just a process of elimination to find out which one it is. If not, the water is likely to be coming from the sink (use above link). Sometimes by removing the soap dispenser drawer and carefully observing inside the soap dispenser you can clearly see water dripping in at regular intervals.
Blocked water valve filters:
I've come across cases where a filter in the water valve has become caked in a brown sludgy mud-like substance due to disturbances in the plumbing. This could be because of work carried out on internal plumbing or even after workmen have turned the water off in the street to work on the water mains. After the water is turned back on, muddy or gritty water can enter the household pipework and when you use the washing machine it can draw this contaminated water into it.
In this scenario very fine grit or muck can get past the filter and stop it shutting off properly, or the filter is so blocked that water pressure to the valve is reduced enough to prevent the valve shutting off properly. Remove the water valve filter with some pliers and thoroughly clean it out. If the fault persists, replace the valve.
Important things to watch out for are -
- Washing machine water valves need a certain amount of water pressure to actually ensure the water is shut off properly. Therefore, if your water pressure is very low, it can seep in past the closed valve. This problem is less likely to suddenly appear unless your water pressure has suddenly dropped. It's more likely to be a problem with a new installation. ( Related: Low water pressure and washing machines )
- A faulty tap can mean that although you turn it off, the water supply isn't actually cut, so be careful of assuming if the fault still occurs, that you have definitely discounted the water valves. If unsure, you would have to disconnect the hot and cold fill hoses to ensure the water supply is properly cut when the taps are turned off. This problem is a lot more common with water taps that turn off with a red or blue plastic lever.
- If the washing machine has just been filling, you may get some dripping of water into the soap dispenser for a few minutes after. Don't mistake this for a valve not shutting off properly.
- If the water ever gets turned off while work is carried out on the water mains in the street or for major plumbing in your home, run lots of water in the house through taps at the sinks until it runs clear after the water is turned back on.
Faulty water valves should be replaced or there is risk of flooding.