Direct answer: If a washer fills when it is off, the most likely cause is a washer water inlet valve that is stuck partly open and letting water seep in all the time.
Most likely: On most machines, a slow tub fill with the power off is a mechanical valve problem, not a drain problem and not something a reset fixes.
Start by confirming where the water is coming from. If the tub is empty after a cycle but slowly gains clean water while the washer sits unused, the inlet side is the first place to look. Reality check: this is one of the more common washer leaks that happens even when nobody is using the machine. Common wrong move: unplugging the washer and assuming the problem is gone while the supply faucets stay open.
Don’t start with: Do not start by replacing the washer control board or tearing into the drain system. First prove whether water is sneaking past the inlet valve.
You leave the washer empty, come back hours later, and there is fresh-looking water in the basket or tub.
Start here: Turn off both supply faucets. If the water level stops rising, focus on the washer water inlet valve.
The machine has no power but water still creeps in.
Start here: That strongly points to a washer water inlet valve stuck open mechanically, because unplugging removes the control signal.
The tub is dry when idle for long periods, but water appears after use or while draining.
Start here: That is more likely a run-time leak or drain issue than an off-state fill problem.
The water temperature or stain pattern suggests one side is feeding more than the other.
Start here: Check each supply hose and faucet, then suspect the hot or cold side of the washer water inlet valve.
This is the classic cause when clean water enters the tub with the washer off. Mineral buildup or wear keeps the valve from sealing.
Quick check: Shut off the wall faucets. If the tub stops filling, the leak path is through the inlet side.
Sediment from the supply line can keep the valve from sealing all the way, especially after plumbing work or a recent shutoff.
Quick check: Remove power, close the faucets, disconnect the hoses, and inspect the inlet screens for grit or scale.
Less common, but possible if the washer fills only when plugged in and stops when unplugged.
Quick check: If water enters only with power connected and stops immediately when unplugged, the control side needs closer diagnosis.
Sometimes homeowners see water in the tub and assume it is filling, when it is actually drain water backing up or a nearby leak entering the basket area.
Quick check: Look at the water. Clean clear water points to supply fill. Gray, soapy, or linty water points elsewhere.
You want to separate a supply-side leak from a drain problem before touching parts.
Next move: If you confirm clean water is entering from the fill side, stay on this page and keep going. If the water is dirty, soapy, or seems to back up from the drain side, this is not the usual off-state fill problem.
What to conclude: Clear water usually means the washer is being fed by the house supply. Dirty water points toward a drain backup or a different leak path.
This is the fastest safe test for a leaking washer water inlet valve.
Next move: If the water level stops rising with the faucets closed, the problem is on the washer inlet side. If the water level still rises with both faucets fully closed, the water is likely not coming through the washer inlet valve.
What to conclude: A stopped fill after closing the faucets is strong evidence that water was sneaking past the washer water inlet valve. If the level keeps rising, look for a drain backup, another leak source, or a faucet that is not actually shutting off.
A washer water inlet valve can fail two different ways: mechanically stuck open or electrically energized when it should be off.
Next move: If water enters even with the washer unplugged, the washer water inlet valve is the likely failed part. If the filling happens only when the washer has power, the valve may still be good and the control may be sending power when it should not.
Sediment can hold the valve slightly open, and a quick inspection may explain a recent sudden problem.
Next move: If the washer stays dry after cleaning debris from the inlet side, the valve may have been held open by sediment and you may be done. If the tub still slowly fills, the washer water inlet valve is no longer sealing reliably and replacement is the usual fix.
By now you should know whether this is a straightforward valve leak or a less common electrical problem.
A good result: If the tub stays dry with the faucets on and the washer off, the repair is confirmed.
If not: If a new valve is installed correctly and the washer still fills only when powered, the control circuit needs professional diagnosis.
What to conclude: Most homeowners can handle a confirmed washer water inlet valve replacement. A control-driven fill problem is less common, less certain, and not a good guess-and-buy situation.
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Most of the time, water is slipping past a washer water inlet valve that is not sealing fully. The valve can stick open from wear, mineral buildup, or debris.
That is the strongest homeowner clue that the washer water inlet valve is mechanically stuck open. With no power connected, the control is out of the picture.
Yes, but it is less common. If the washer fills only when plugged in and stops when unplugged, the control or wiring may be energizing the valve when it should not.
It is better not to. A slow seep can become a full overflow, especially if the valve gets worse suddenly. Close the supply faucets until you fix it.
Not automatically. Replace the hoses only if they are cracked, bulged, rusted at the ends, or leaking at the couplings. A bad washer water inlet valve does not by itself mean the hoses are bad.
Dirty, soapy, or linty water points away from an inlet valve seep and more toward a drain backup or another leak path. That is a different problem than a washer filling itself with fresh water.