- Strong airflow or ventilation
- Rarely used bathrooms
- Basement floor drains
- Laundry standpipes
For a weekend trip or even a two-week vacation, your P-traps will generally remain full.
The issue is more likely during extended trips of three weeks or longer, especially in drains that aren’t used regularly.
Does the Paper-and-Glass Trick Work?
Only in theory.
Covering a drain can help reduce evaporation and provide an extra barrier if the trap eventually dries out.
The problem is that an upside-down drinking glass rarely creates an airtight seal.
Without a tight seal:
- Air can still circulate.
- Odors can still escape.
- Insects may still find a way through.
- The paper can absorb moisture and become ineffective.
In other words, the plumbing principle is sound—but the viral setup isn’t particularly reliable.
A Better Way to Prepare Your Drains
Instead of balancing a glass on top of a piece of paper, try these simple steps before leaving town.
1. Refill Every P-Trap
Run water in every sink, shower, and bathtub for about 10 to 20 seconds.
Don’t forget to:
- Flush every toilet.
- Run water into rarely used sinks.
- Fill basement floor drains if accessible.
- Add water to laundry standpipes if needed.
This restores the water seal that protects your home.
2. Seal the Drain Properly
If you’ll be away for several weeks, consider covering drain openings with something that actually seals them, such as:
- Built-in sink stoppers
- Rubber drain plugs
- Silicone drain covers
- Plastic wrap secured with painter’s tape (as a temporary option)
The goal is to reduce evaporation while creating a more effective physical barrier.
3. Add Mineral Oil for Long Trips (Optional)
A trick many plumbers recommend for extended absences is adding about one tablespoon of mineral oil after filling the trap with water.
The mineral oil floats on top of the water and slows evaporation significantly.
Use mineral oil only—not cooking oil, which can become rancid and contribute to plumbing problems.
Other Vacation Plumbing Tips
A few additional precautions can help prevent unpleasant surprises when you return:
- Empty trash bins before leaving.
- Clean the garbage disposal to reduce odors.
- In cold climates, make sure exposed pipes are protected from freezing.
- If you’ll be away for an extended period, consider shutting off your home’s main water supply to reduce the risk of leaks.
Myth vs. Reality
Myth: Placing paper and an upside-down glass over the sink drain will reliably prevent sewer odors and pests.
Reality: Unless the cover forms a tight seal, it offers limited protection. The most effective approach is to keep your P-traps full of water and, if necessary, seal the drain with a properly fitting stopper or drain cover.
The Bottom Line
The viral sink hack isn’t completely without logic—it just isn’t the best solution.
If you’re leaving home for a longer trip, the simplest and most effective way to protect your plumbing is to:
- Refill every P-trap with fresh water.
- Seal drains with properly fitting covers if needed.
- Consider adding a small amount of mineral oil for extended absences.
These straightforward steps can help keep sewer odors and unwanted pests out of your home, without relying on a glass-balancing trick that may not hold up once you walk out the door.