Newly installed sump pump sitting in a basement sump pit
Generic photo: Famartin · CC BY-SA 4.0

Sewer or musty smell from the sump pit

A clean sump pit should not smell like sewage. Most odors come from a pit that has dried out and no longer seals the drain tile lines, stagnant water, organic buildup, or nearby plumbing traps that have dried or been siphoned. A strong, persistent sewage smell can mean a leaking sewer line near the pit.

Cross-checked ~30 min easyBrands: All

Before you start

  • Unplug the pump before cleaning the pit.
  • If the odor is strong sewage or the household is on a sewage ejector, treat it as a plumbing problem and refer to a plumber.

Diagnostic steps

Unlock all 6 steps with expected values

Full library + AI assistant for $34.90, one time.

Get lifetime access

OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work.

More sump & well pumps guides

Guide · Sump / Well Pump

Sump pump trips the GFCI or breaker

A GFCI that trips with a sump pump is usually detecting real current leakage from a pump motor taking on water, a damaged cord or splice, or another load on the same circuit. Isolate the pump from the circuit before blaming the GFCI, and never bypass the protection on a pump in water.

4 steps ~45 minmoderate
Guide · Sump / Well Pump

Sump pump keeps cycling when it has not rained

The most common cause is water returning from the discharge pipe through a failed or missing check valve, so the pump moves the same water again and again. Other causes are a small basin, a float set too close, a high water table or a leak feeding the pit.

4 steps ~40 mineasy
Guide · Sump / Well Pump

Well pump runs nonstop and never reaches cut-out pressure

The pump cannot build enough pressure to open the pressure switch, either because water is escaping (leak, running fixture, failed check valve), the pump is worn or has lost prime, the well cannot keep up, or the cut-out is set above what the pump can make. Running dry can ruin the pump, so act quickly.

5 steps ~60 minadvanced
Sewer or musty smell from the sump pit · OnCall Tech