LG Washer Filling When Not in Use? Causes & Fix

Identify the water source#

Before changing any part, decide where the water originates, because it splits the diagnosis cleanly. Clean water accumulating slowly means the inlet valve is not sealing and supply water is weeping in. Dirty or soapy water appearing instead points to the drain system siphoning used water back into the tub. That single observation tells you whether to look at the supply side or the drain side.

Causes at a glance#

Working through the causes#

Failed water inlet valve (55%). The inlet valve, LG part 5220FR2006H on most WM-series washers, is solenoid-operated: it opens when energized and should close completely when power is removed. As it wears it no longer seals, so clean water trickles in with the washer off. The valve is replaced rather than cleaned. Drain-hose backflow (30%). If the drain hose is pushed too far into the standpipe, beyond about the six-inch maximum insertion, or a nearby fixture drains and creates a siphon, used water can flow back into the tub. The tell is dirty or soapy water. Correct the standpipe insertion depth and secure the hose so it cannot siphon. Pressure-switch air leak (15%). The pressure switch reads water level through a thin air hose to the tub. A pinhole or a disconnected hose keeps it from sensing the true level, so the board can misjudge fill. Inspect the pressure-switch hose for leaks or a loose connection and reseat or replace it.

Diagnose it, step by step#

1. Turn off both supply valves at the wall — this stops any inlet-valve leak immediately.
2. Note the color of the standing water: clean points to the inlet valve, dirty points to the drain.
3. Check how far the drain hose sits in the standpipe and pull it back to the correct depth if over-inserted.
4. Inspect the pressure-switch air hose for pinholes or a disconnected end.
5. If clean water keeps rising with the drain ruled out, the inlet valve needs replacing.

Mitigate it now#

While you diagnose, turn off both supply valves whenever the washer is idle. A failed inlet valve with the supplies left open can slowly flood a laundry room, so shutting them off is the surest interim safeguard.

Preventing a repeat#

• Close both supply valves whenever you are away for more than a day.
• Keep the drain hose at the correct standpipe depth so it cannot siphon.
• Replace the inlet valve at the first sign it seeps rather than waiting for a flood.
• Inspect the pressure-switch hose during any service so a small leak does not linger.
• Swap aging rubber fill hoses for braided steel lines that resist bursting under pressure.
• Check that the drain hose is secured so it cannot work deeper into the standpipe.
• On WM-series units, treat the inlet valve as a wear item and replace it once it starts seeping.

Washer filling while idle? Our technicians repair LG washers same-day across Sacramento and the Bay Area. Book your repair.