This article looks at how a washing machine fills with water when switched off. Sometimes overnight. When the washing machine is not in use, water may slowly rise in the drum. It could be with either clean or dirty water. It’s important to work out which type of water it is because they have different sources.
There are only 2 places where water can get into a washing machine’s drum. Either through a water valve, or through the drain hose. It’s impossible for water to get in any other way. If the water is very clean it must be coming in through a water valve. If it is dirty it may be coming in through the drain hose from the sink. Both possibilities are described in detail below.
Water coming in through a water valve
When a water valve isn’t being used it shouldn’t let any water through. It’s possible for a fault inside it to prevent one shutting off properly though. A small bit of grit or debris could also get past the filter and stop it from closing properly. It’s unlikely though unless it’s an old washing machine, or maybe there is some damage to the filter. Either of these issues can result in water slowly seeping into the machine.
Water rising inside the drum may only be noticed if the washing machine is left unused (with the water tap left on) over night, or over a several day period. This is why ideally you should always turn off the taps after using the washing machine.
Water Pressure Too Low
A third possible valve related cause is if the water pressure is very low. Bizarrely the valves rely on a minimum amount water pressure to push against a rubber flange and shut water off. You can get water seeping past the seal inside if the water pressure is extremely low.
The first thing to try is to turn off the taps
If the water inside the drum is clean, then water could be getting past the water valve. Turn off the water tap(s) to the washing machine. Does this stop the water coming in? If it doesn’t, move onto the drain hose possibility below. However, you must ensure the tap is not faulty by removing the fill hose from the machine and ensuring no water comes through with the tap turned off. This is the only way to be 100% sure water is being properly turned off. This is because a tap can be faulty inside and not turn off properly.
Try Seeing if Water is Dripping in Through the Soap Dispenser
Sometimes, by removing the soap dispenser drawer and carefully observing inside the soap dispenser you can see water slowly dripping in at regular intervals from the nozzles at the top. Don’t check this if the washing machine has just been filling though. You may get some dripping of water into the soap dispenser for a while after. If there is a slow drip you might also (but not necessarily) see a black jelly-like gunge around where the water comes in.
Check the Water Valve Filter
Water pressure to the valve might be reduced enough to prevent the valve shutting off properly if the filter is severely blocked. Turn off the tap(s), remove the fill hose(s) and the water valve filter is easily seen at the back of the valve. Usually it will be quite clean – with no need to remove it. If it is definitely blocked though carefully pull it out with some flat pliers. Clean it out under a running tap. Be very careful not to damage it! Even a very small hole will compromise its filtering abilities and let debris inside the valve.
Does the water valve need replacing?
If you can’t find a filter blockage, the water pressure is OK, and turning off the tab stops water entering the drum overnight you need to get the water valve replaced as soon as possible.
Water getting in through the drain hose
The only other place water could possibly get into the drum is by siphoning up the drain hose. This shouldn’t be possible if the drain hose is plumbed in properly. However, incorrect fitting can create circumstances where water runs down the drain hose or is siphoned up through it. Water is pumped through the drain hose out to the drain by one of 2 different ways –
- To a spout on the u-bend under the sink
- Down a stand pipe that the drain hose is pushed into
If the drain hose is connected to the u-bend
Water could be running into the machine from the sink if the drain hose is connected directly to the u-bend under the sink. If the water is entering through the drain hose from the u-bend the water might be smelly or dirty. Check this article for details Check the drain hose is installed properly.
If the drain hose pumps into a stand pipe
If your washing machine does not pump out into the u-bend it may be pushed into a larger stand pipe. You shouldn’t get this fault. There are rare circumstances where water could be sucked back into the machine though. For example, if the stand pipe is submerged in water through a blocked grate and the drain hose is sealed into the standpipe instead of sitting in it with an air gap around it. (Check the drain hose is installed properly).
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yes you need a trap under sink does have non return valve on it, my daughter had same problem buy from plumbers or B & Q
I’ve seen some drain hose connections with a rubber flap which acts as a non return valve but most I’ve come across didn’t have them unless modern ones have been improved.
My washing machine has been filling with water while unattended. Usually just 2 or 3 inches, but then last month it actually overflowed so I called a repairman. He said it didn’t look like the problem was with the washer, so he turned off the water supply and said to watch it. And water kept coming in anyway, so he says the drain is the only place it could be coming from.
So then I called a plumber, who sent out a young assistant who messed around with my sump pump (the washer is in my unfinished basement) and then said I probably have a block in my sewer line, which apparently is an expensive fix. He too said well keep an eye on it and call us back.
Since then I’ve determined it seems to be tied to the amount of rainfall we get. But I’m in the Seattle area and we’ve had a much rainier winter than usual, so it’s hard to be scientific about this. On one dry weekend the washer stayed dry. I think back when it overflowed, it was pouring, but that was before I knew to watch the weather. The water seems to be clean, like tap water. What the heck? The washer is below ground level.
thanks!!
Hello Dianne. All known causes of water getting inside the drum when the washing machine are described in my article. There are only 2 possible ways, either through the water valve or through the drain hose.
I’ve just spent an hour rewriting and hopefully improving my article above . So please read it again for better insight. If your washer is in the basement is it plumbed in normally? It’s not pumping higher than 3 feet or so is it?
Hi Andy
18 months ago we had a combi-boiler installed and got rid of our hot & cold water tanks. Since then, we’ve had problems with the washing machine, shower and toilet leaking. (High-pressure fittings have been put in the toilet now and a new valve installed in the shower, which seems to have solved these problems.)
Water had been leaking into our 15-year-old washing machine. We bought a new one last year, but have had the same problem with it. We’ve had it checked as part of its warranty. The Zanussi engineer said water was leaking into the drum due to a faulty inlet valve in the machine, which he changed.
Unfortunately, the problem has started again, just two months after the new valve was fitted.
There’s a u-bend under the sink for drainage, but it seems unlikely that this is the source of the problem as the water leaking into the drum is clean and doesn’t smell.
I know your advice is to ensure that the water pressure isn’t too low, but is there also a problem if it’s too high? Either way, I’d be very grateful if you could give me any advice.
Many thanks
Same problem with brand new washing machine after 1 day. It’s now been replaced today and after 2 hours it was full of water ! I thought the first machine was faulty but obviously not! Electrics all turned off and water supply to machine all off when not in use and still filling up!
It’s getting me down.
Had just about enough!!
Hello Deliment. Have you gone through all my article? All possible causes are there so it has to be one of them.
Hi Deliment. Needless to say if you’ve had 2 new washing machines let water in then you can discount faults with the water valve, or filter. It must be the plumbing. Either water is siphoning in from the sink (if the drain hose is connected to the u-bend) or the water pressure is way too low. Go through the article, eliminate things about the washing machine because 2 new machines surely can’t have the same rare fault ,and check everything else.
The only other thing could be if maybe the water pressure is good enough, but when you turn off the tap, the tap isn’t shutting off the water properly and some water is seeping through the valve. This can be checked for by removing the fill hose and seeing if the tap is shutting off the water properly.