Troubleshooting Pumps: There’s a Sewer Gas Smell

What to check when property owners complain they have sewer gas smells by a sewage ejector or grinder in the basement or by their pump tank

Troubleshooting Pumps: There’s a Sewer Gas Smell

Interested in Systems/ATUs?

Get Systems/ATUs articles, news and videos right in your inbox! Sign up now.

Systems/ATUs + Get Alerts

When property owners complain they have sewer gas smells by a sewage ejector or grinder in the basement or by their pump tank, you should take that complaint seriously.

Hydrogen sulfide is dangerous even at low levels. Prolonged exposure to sewer gas can cause irritability, headaches, fatigue, sinus infections, bronchitis, pneumonia, loss of appetite, poor memory and dizziness. It affects people and pets that are exposed to it over a long period of time. Even if the smell comes and goes, it needs to be addressed.  

If there is an odor from a sewage pump in the basement consider these steps:

  • Make sure all traps in the basement have water in them to prevent sewer gas from coming back into the home.
  • Check for improper or outdated plumbing. In some older homes it’s possible the venting was not properly connected as fixtures or additions were added to home. A detailed interior plumbing inspection may be needed.
  • Check for a clean-out plug inside the floor drain by removing the grate that covers the opening and making sure there's a plug inside the drain bowl. If the plug is missing, there's a direct path for sewer gas to bypass the water trap. Sometimes, the plugs are removed to clean sewer lines and not replaced.
  • Vent the pump. A common problem is the plumbing vent located on the roof. It’s necessary to allow the pressure in the drainpipes to equalize as wastewater flows through them. Without this vent, sinks, tubs and toilets would gurgle, traps dry out and odors come into the home. These plumbing vents can freeze closed during prolonged cold periods or get clogged with leaves or other debris.
  • Gaskets and seals on the pump basin may need maintenance. Remove the cover and flanges, and clean all sealing surfaces. Replace foam gaskets and lightly grease O-rings and grommets and reassemble.

If there is odor by the pump tank, it might be related to:

  • An improper seal on an electrical conduit
  • An improper seal on the pump tank lid – The newer plastic lids have a rubber seal that helps keep odors in the tank. They must also be properly secured in place with lag screws or other fasteners. If a concrete lid is leaking odors out of the manhole, weather stripping or other materials can be used to create a temporary seal that will contain odors but still allow for proper maintenance of the tank. This seal will need to be replaced after maintenance.   

About the author 
Sara Heger, Ph.D., is an engineer, researcher and instructor in the Onsite Sewage Treatment Program in the Water Resources Center at the University of Minnesota. She presents at many local and national training events regarding the design, installation, and management of septic systems and related research. Heger is education chair of the Minnesota Onsite Wastewater Association and the National Onsite Wastewater Recycling Association, and she serves on the NSF International Committee on Wastewater Treatment Systems. Ask Heger questions about septic system maintenance and operation by sending an email to

This article is part of a series on troubleshooting pumps:


Comments on this site are submitted by users and are not endorsed by nor do they reflect the views or opinions of COLE Publishing, Inc. Comments are moderated before being posted.