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How to Get Rid of Swamp Gas Odor

Daisy Peasblossom Fernchild

Swamp gas is the common name for the hydrogen sulfide from decaying matter. In small amounts, hydrogen sulfide is relatively harmless. However, it becomes quite dangerous when present in large amounts, especially in confined spaces.

Dry traps in drains under sinks and in floors are a common cause of swamp gas odor.

It is colorless, but the odor is quite noticeable when initially entering an area, having a distinctive "rotten egg" smell. Olfactory fatigue quickly sets in, however, and people quickly stop noticing it in their environment. It is heavier than air, and tends to collect in places like sewer pipes or basements.

What to do if You Have Swamp Gas Odor in Your Home

  1. Open doors and windows. Ventilate the entire house to discourage concentration of the gas. Note that swamp gas has a different odor from natural gas, which has a scent added to it as a safety measure. If the odor is extremely heavy or you suspect it might be natural gas or propane, skip this and all other subsequent steps, and call a plumber or utility person using a neighbor's phone.

  2. Check all drains to make sure they are working properly. A common cause of swamp gas odor is a drain trap that has been allowed to become dry. Water in the elbow-bends of these traps creates a seal to prevent gas seepage from the sewer.

  3. Check for noticeable leaks around toilet bowls or under sinks. Make sure decaying matter has not remained in garbage disposals. Dissolve baking soda and pour into drains that have traps.

  4. Change and scrub out cat litter boxes, bird cages or other areas where pet wastes might collect. Empty and scrub out garbage containers. Change filters on water coolers, flush out cooling systems that use water.

  5. Call your local plumber or utility company if you cannot find any reasonable cause and the odor persists. One common cause of swamp gas odor is a cracked sewer pipe that is leaking under your house.

  6. Tip

    Sulfur is relatively harmless in small amounts and may sometimes appear in high enough concentrations to give local drinking water that distinctive "rotten egg" smell.


    If you suspect a high concentration of any kind of gas, do not enter the building and definitely do not light any sort of flame. Call the authorities immediately from a phone that is not located inside the problem area.