Cottage Q&A: Will this trick banish outhouse stench?

An outhouse in the woods with its door standing open By stbar1964/Shutterstock

My brother-in-law (a chemist) puts about half a cup of vinegar and a handful of dry leaves down the outhouse pit, to help with odour. Anecdotally, it works. Why might that be? Does it do any harm?—Full of Piss and Vinegar

Even after contacting Health Canada, Environment Canada, the National Research Council, the National Collaborating Centre for Environmental Health, vinegar manufacturers, several university research departments, and chemical engineering and wastewater treatment experts—not to mention hours of Googling—we still couldn’t find anyone who would endorse your relative’s outhouse trick.

“From a wastewater perspective, I’d see little value in doing that,” says John Rowse, the executive director of the B.C. Onsite Sewage Association in Victoria. “To my mind, it would really have little or no effect.”

But is it harmful? Well, as Mark Green, the chief building official for Ontario’s Leeds, Grenville & Lanark District Health Unit points out, “Pit privies are designed to receive human body waste. Leaves and vinegar aren’t the same as the material you have coming out of your intestines.”

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Studies on eliminating food-borne pathogens and disinfecting hard surfaces show that vinegar has antimicrobial properties. Perhaps useful if you’re washing fruit or cleaning your kitchen counter, but in an outhouse pit, where you need bacteria, not so much. “Vinegar is an acid,” says Fraser Sneddon of Sun-Mar, which makes composting toilets. “It’s changing the pH. If anything, it could kill some of the bacteria.” As for the leaves, they’re a bulking material, and they might helpfully soak up some of the moisture in the pit, says Rowse. However, Sneddon warns, because they bring extra carbon to the equation, it’s possible that too much could ramp up decomposition and produce more methane, sulphur, and other stinky gases.

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All that said, it sounds like your brother-in-law is using this cheap, simple trick sparingly, and it’s working for him. “I think you would really have to overdo it with the vinegar and the leaves to have any negative reaction,” admits Rowse.

But if Mr. Chemistry starts dumping great sackfuls of leaves and pouring litres of vinegar into the pit, shut the experiment down and tell him to ventilate.

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