We installed a toilet inside our cottage, and since then there is a sewage smell outside that seems to be coming from our vent stack. There are lots of trees and a large hill right behind our cottage. What is the best way to solve this problem?—Sinclair Robinson, via email
That will depend on what’s causing the problem. You mention the trees and a big hill, which suggests that you think that they’re playing a role.
Good instincts: “If the new toilet included a new vent, then an odour is possible because of airflow downdraft from the topography and the tree cover,” says Sandy Bos, an inspector with the Township of Muskoka Lakes. If the objects around the cottage are taller than the vent pipe, negative pressure can pull the septic gas exiting the vent back down to settle around your cottage. Extending the vent stack could help, says Bos.
6 things that should never go into your septic tank
On the other hand, the smell may have nothing to do with new plumbing or trees or hills. A properly functioning septic system shouldn’t produce odours, says Rob Davis, the owner of EcoEthic in Sunderland, Ont. “As I say in my septic seminars, ‘If you are getting odours on that side of the cottage, your septic tank has some indigestion.’ ” If you added another toilet to the cottage to accommodate more people, your system could be struggling to keep up—more people usually means more water going into the tank, and that can interfere with the proper breakdown of solids.
Not to play the blame game, but are you giving your septic the TLC that it needs? Sure, you probably aren’t flushing diapers and cigarettes down the toilet or pouring massive amounts of bacon grease down the sink. But, you “could be using too much chlorinated dish detergent or laundry detergent,” says Davis. These products kill the good microbes that a septic tank needs to function efficiently. So does too much antibacterial soap. Remember that until about March 2020, we weren’t all washing our hands 45 times per day with massive amounts of germ-killing soap (while singing “Happy Birthday” twice).
Cottage Q&A: Antibacterial soap vs. the septic system
Still, if you feel your septic system habits are top notch, it’s best to call in an expert to assess the situation in person. A licensed plumber can help diagnose the problem.
Got a question for Cottage Q&A? Send it to answers@cottagelife.com.
This article was originally published in the Winter 2023 issue of Cottage Life magazine.
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