Why Is My Sump Pump Leaking?

A leaking sump pump usually means one of three things: a failed shaft seal, a damaged housing gasket, or a loose discharge connection. The fix depends on where the leak is coming from.

Where is the leak coming from?

Look closely at the pump before doing anything else.

• Leak from the shaft area or oil in the pit — The motor shaft seal has failed. Oil inside the motor housing is leaking past the seal into the pit. This is repairable without replacing the pump.
• Leak from the base or housing seam — A housing gasket has failed or the housing is cracked. May be repairable depending on severity.
• Leak from the discharge pipe connection — The pipe fitting or check valve has loosened or failed. Usually a straightforward fix.

If you see oil in the pit, read this first

Oil in the sump pit almost always means shaft seal failure. The shaft seal keeps motor oil separated from the water side of the pump. When it wears out — typically after 5 to 10 years — motor oil leaks through the shaft and drips into the pit.

The good news: the motor itself is usually fine. The pump doesn’t need to be replaced. A $39.99 seal kit fixes the problem.

→ Why Is There Oil in My Sump Pit? Read the full diagnosis

If the pump is leaking water but no oil

Check the discharge pipe connection first. A loose fitting at the pump outlet is the most common source of water leaks that aren’t seal-related. Tighten the connection or replace the fitting.

If water is coming from the housing itself, the gasket may have failed. This is also repairable but requires disassembly.