We’re Going on Vacation, and My In-Laws Told Me to Cover My Sink Drain with a Piece of Paper and Place a Glass Upside Down Over It. I Didn’t Want to Seem Ignorant by Asking, but I’m Really Curious. Does Anyone Know Why?

For longer trips—especially several weeks or months—the more important step is making sure the P-trap contains water. Before leaving, simply run water in every sink, shower, bathtub, and floor drain. This refills the traps and helps maintain the seal that blocks sewer gases.

Some homeowners also pour a small amount of mineral oil into infrequently used drains before a long trip. The oil floats on top of the water and slows evaporation, helping the trap stay filled longer.

While you’re preparing for vacation, it’s also a good idea to:

• Empty the trash.
• Clean food scraps from the sink.
• Run the garbage disposal with cold water if you have one.
• Check that faucets aren’t dripping.
• Consider turning off the main water supply if you’ll be away for an extended period (if appropriate for your home).

So, is the paper-and-glass trick necessary?

Not always.