Why You Should Be Using Oil in Your Floor Drains

Updated: Jun. 24, 2024

Keep water seal in your floor drains from drying out with a thin layer of cooking oil. It'll keep foul odors out of your house.

Under every drain in your house, there’s a trap, known as the p-trap, that holds water and prevents sewer gas from flowing up into the air you breathe. But if you have an abandoned shower in a spare bathroom or a floor drain in the basement that never gets used, the water in the trap can eventually evaporate. That lets in stinky—or even dangerous—sewer gases. So, how do you keep the water in the p-trap from evaporating and the air from filling with sulfuric odor?

Cooking oil. It’s a little trick we’ve learned over the years at Family Handyman by chatting with plumbers and homeowners.

How To Get Rid of Smelly Drains

For starters, if the water in your p-trap has evaporated, pour a bucket of water down the drain to refill the trap. Then add the oil, about a teaspoon for each inch of the pipe’s diameter.

The floating oil forms a seal over the water and prevents evaporation—without raising your cholesterol.

Why You Should Be Using Oil In Your Floor DrainsTMB STUDIO