Before leaving for a trip, it’s natural to want your home to remain clean, fresh, and free of unpleasant surprises. One widely shared tip suggests covering a sink drain with paper and an upside-down glass to block odors and insects. While inventive, this idea doesn’t fully align with how household plumbing systems are designed to function.
Most drains in sinks, showers, and tubs include a curved section of pipe that holds a small amount of water. This water acts as a barrier, preventing sewer gases and pests from traveling back into the home. When a drain goes unused for an extended period, especially during warm or dry weather, that water can slowly evaporate. Short trips rarely cause issues, but longer absences can weaken this protective seal.
The paper-and-glass method is intended to slow evaporation, but it often falls short. Paper can shift, absorb moisture, or slip into the drain, and a glass rarely creates an airtight seal. Without a proper barrier, evaporation may continue and odors can still escape. Understanding this limitation helps explain why the trick doesn’t always deliver reliable results.
A more effective approach is simple and practical. Before you leave, run water briefly in every sink, shower, tub, and floor drain, and flush all toilets to refresh the water seals. Closing built-in stoppers or using snug silicone drain covers adds extra protection. For longer trips, adding a small amount of mineral oil on top of the water can slow evaporation even further. Rather than relying on shortcuts, a basic understanding of plumbing is the best way to keep your home fresh while you’re away.