The bags are packed, the thermostat is turned down, the lights are on a timer. Then you come home a week later and the kitchen smells like a sewer. The cause is almost always the same, and there is a two-second trick to prevent it before you leave: a sheet of paper and a glass, placed in the sink.
Why the kitchen smells bad after a trip
Under every sink there is a curved pipe called a P-trap. It always holds a little water, and that water is what blocks sewer gases from coming back up into the house. As long as the sink is used every day, the trap stays full.
When nobody runs the tap for several days, that water slowly evaporates. Warm, dry indoor air speeds it up, and the heating season is exactly when that happens. Once the seal is gone, odors from the drain line rise freely into the kitchen. As the South Davis Sewer District explains, an extended absence is one of the classic causes of a dry trap.
The trick: paper and a glass
Before leaving, run water in the sink for a few seconds so the trap is full. Then lay a sheet of paper flat over the drain opening, and set an upside-down glass or a small plate on top to hold it in place.
The paper and the glass create a lid. Less air circulates over the water in the trap, so it evaporates more slowly, and if a little odor does escape, it stays trapped under the glass instead of filling the room. A variation shared widely online uses a plastic bottle filled with water, turned upside down in the drain, to keep topping the trap up drop by drop.
What plumbers add to it
The paper trick helps, but the basics matter more:
- Fill every drain before you leave, not only the kitchen sink: bathroom sinks, the shower, the tub and any floor drain in the basement or laundry room.
- For long absences, pour a little mineral oil into seldom-used drains after filling them. It floats on the water and slows evaporation considerably.
- Leave the toilet lids down and run water in every drain as soon as you get home.
- Take out the trash and empty the garbage disposal with a good rinse, since leftover food is the other big source of kitchen smells.
When it is not the trap
If the smell persists after refilling the drains, the problem is elsewhere: a partial clog, a blocked vent pipe or a damaged trap. In that case, call a licensed plumber. And if the sink smells even when you use it daily, try the coffee grounds and baking soda paste, and check the dirtiest place in your kitchen.
With Thanksgiving and holiday trips coming, it is worth adding to the checklist before you lock the door.
A full trap, a sheet of paper and an upside-down glass. You come home to a kitchen that smells like a kitchen. That’s the trick.
