How to eliminate septic tank odour

Updated February 21, 2017

Individual septic tanks have the potential to develop an odour that can be released into the air. The odour develops from a pH level that is too acidic. Microorganisms exist in the septic tank and digest the organic matter -- yet, in turn, they produce large quantities of hydrogen sulphide, methane gas, carbon dioxide and organic acids. These by-products result in a pH level that is too acidic for the microorganisms and they stop digesting the organic matter, resulting in a release of hydrogen sulphide gas which smells like rotten eggs. Homeowners who experience this problem often take action in an attempt to eliminate the unpleasant smell. If you have this problem, utilise a common household product to treat the septic tank and create a less acidic pH level. You can also take other steps to prevent a potential septic tank odour problem.

Pour 125 g (1 cup) of baking soda down any toilet or drain once a week to maintain a good pH level in your septic tank of 6.8 to 7.6.

Don't use more water than you need. If you use excess water, you will flush the baking soda out of the septic system more quickly and push waste out of the tank that hasn't been digested by the microorganisms.

Avoid flushing things down the toilet that microorganisms cannot digest, such as coffee grounds, plastic, cigarette butts, cat litter or facial tissues. Throw these type of items in the rubbish.

Hire a professional septic tank cleaning service to pump out the accumulated waste in your tank every three to five years.


Never pour any type of harsh chemicals or lye into your toilet or drains. These can kill off the beneficial microorganisms.

Things You'll Need

  • Baking soda
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About the Author

Based in Texas, Cynthia Measom has been writing various parenting, business and finance and education articles since 2011. Her articles have appeared on websites such as The Bump and Motley Fool. Measom received a Bachelor of Arts in English from the University of Texas at Austin.