Why Does My Sump Pump Smell? (And What Can I Do About It?)

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Sump pump odors are your sump system’s way of letting you know it needs attention. Installed in the basement floor and concealed beneath a cover, a sump basin can be one of the most seldom-inspected areas of the house. It’s there to remove ground water rising up through the foundation or water leaks in the basement from sources like a ruptured pipe. As the basin fills, the pump actuates and pumps water through a discharge line to an exterior point, usually somewhere in the back yard. Because all this happens automatically, many homeowners don’t give much attention to this critical system—unless the pump fails and basement flooding occurs, or sump pump odors begin to be noticeable.

If a persistent musty, mildew-like smell pervades your basement and other, more obvious causes are ruled out, check the sump pump basin. Here’s what to look for:

Stagnant Water

The on/off float switch that actuates a sump pump is designed to leave enough water in the bottom of the basin to keep the pump inlet submerged. If the pump actuates regularly, the water is frequently pumped out and replaced by fresh incoming water. However, if ground water infiltration is minimal, the pump may not actuate for long periods of time. This allows water in the basin to become stagnant and develop mold or mildew that creates odors. Here are two DIY treatments to resolve the odors:

  • Pour five gallons of clean water into the basin. This actuates the float switch and pumps the stagnant water out.
  • After the water is removed, pour a quart of bleach, diluted 50/50, into the remaining residual water in the basin.

Sewage Infiltration

A broken sewer line near or beneath your foundation may gradually leech raw sewage into the ground water. When tainted ground water enters the sump basin, the distinct smell of sewage is emitted. If you notice it, have a qualified plumber inspect the system, locate the cause of sewage infiltration and repair it immediately.

For professional service to pinpoint and resolve sump pump odors, contact Apollo Home.

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