My sister left for vacation and asked me to place an upside-down glass over her kitchen sink drain before I left. She said it was important but never explained why. I did it but now I’m curious: what was it for?

Another Advantage: Preventing Musty Sewer Odors

The trick can also help reduce unpleasant smells from developing while the house sits vacant.

Beneath every sink is a curved section of pipe known as a P-trap. Its purpose is to hold a small amount of water that acts as a seal between your home and the sewer system, preventing gases from traveling back into the house.

During long periods without water use—especially in warm weather—that water can slowly evaporate. If the seal disappears, unpleasant odors may begin drifting into the kitchen.

Covering the drain helps slow evaporation and adds another barrier that keeps odors contained within the plumbing system.

Other Helpful Drain Protection Tips Before Traveling

Homeowners have used similar methods for years to prepare their homes before vacations. Some alternatives include:

• Drain Stopper Method: Place a sink stopper, coaster, or rubber cover over the drain opening to create a seal.
• Baking Soda and Vinegar Cleaning: Pour baking soda followed by white vinegar down the drain before rinsing with hot water to remove food residue and reduce odors.
• Mineral Oil Technique: For longer trips, adding a small amount of mineral oil to the P-trap can create a protective layer that slows water evaporation.

Final Thoughts

My sister’s unusual request turned out to be surprisingly practical rather than overly cautious. Covering a sink drain with an upside-down glass is an easy, inexpensive step that may help prevent pests and unwanted odors while you’re away.

The next time you’re preparing for a vacation, this simple trick might be worth adding to your own pre-trip routine.