A viral travel hack recommends covering a sink drain with paper and placing an upside-down glass over it before leaving home to prevent sewer odors and insects from entering.

The idea is based on a real plumbing feature called the P-trap. This U-shaped pipe beneath sinks, showers, and tubs holds water to create a “water seal” that blocks sewer gases and pests. However, if a drain is not used for several weeks, the water can evaporate, especially in hot or dry weather, allowing unpleasant smells or insects to enter the home.

Experts say the viral trick is not a dependable solution. “Unless the upside-down glass creates a tight seal over the drain opening, it’s unlikely to do much of anything.” They also note that the paper can become damp, making it even less effective at sealing the drain.

A more reliable way to prepare your home before a long trip is to run water through every sink, shower, and bathtub to refill the P-traps. Afterward, seal the drains with built-in stoppers, rubber plugs, silicone drain covers, or plastic wrap to reduce evaporation and keep odors and insects out.

If you plan to be away for an extended period, adding a tablespoon of mineral oil to each drain can help slow water evaporation, allowing the P-traps to remain effective for longer. These simple steps provide better protection than the viral hack and help keep your home fresh while you are away.