Why Do People Cover the Sink Drain With Paper and an Upside-Down Glass Before Vacation?
At first glance, placing a piece of paper over a sink drain and setting an upside-down glass on top may seem like a strange household habit. But there is a practical reason some homeowners use this trick before leaving for vacation: they want to reduce the chance of unpleasant drain odors and keep insects from emerging through the opening.
Although the method can offer a simple extra barrier, it is important to understand what it can—and cannot—do.
1. It May Help Reduce Unpleasant Drain Odors
One reason a home can smell unpleasant after a long absence is that water inside a plumbing trap has evaporated.
Most sinks have a curved section of pipe beneath them called a P-trap. This pipe retains a small amount of water, creating a seal that helps prevent sewer gases from entering the home.
When a drain remains unused for an extended period, particularly in warm or dry conditions, some of that water can evaporate. If the water seal becomes too low or disappears, unpleasant odors may travel back through the drain.
Covering the drain with paper and an upside-down glass may provide an additional barrier between the opening and the room. However, it is not airtight and cannot replace the water seal inside the plumbing.
2. It Can Act as a Physical Barrier Against Insects
Drains and the spaces around plumbing can sometimes provide routes for small insects to enter a home.
A glass placed over the drain opening may make it more difficult for insects to emerge directly into the sink. The paper can help cover the opening and hold its position beneath the glass.
However, this is not a guaranteed pest-control method. Insects can enter through gaps around pipes, windows, doors, and other openings. A properly fitted drain cover or stopper is generally a more practical option.
3. Why Put Paper Under the Glass?
The paper serves as a simple covering for the drain, while the glass holds it in place.
Some versions of this household tip recommend using a damp paper towel after first running water into the drain. The idea is to reduce air movement around the opening and potentially slow evaporation.
There is an important limitation: ordinary paper is porous, and an upside-down drinking glass does not create a dependable airtight seal. The arrangement should therefore be treated as an optional household precaution, not a proven way to prevent sewer gases.
4. What Should You Do Before Leaving for a Long Vacation?
If you want to reduce the chance of drain odors while your home is empty, a few simple steps are more important than the glass trick.
Run water through every drain. This helps ensure the traps contain water before you leave.
Check rarely used drains. Guest bathrooms, showers, laundry rooms, and floor drains may be more likely to dry out.
Clean the sink and remove food debris. Residue in strainers and garbage disposals can contribute to unpleasant smells.
Check beneath sinks for leaks. Repair dripping connections or other plumbing problems before leaving.
Investigate persistent odors. If a drain continues to smell after water has been added, a plumbing issue may need attention.
For an unusually long absence, ask a qualified plumber about appropriate ways to protect rarely used drains.
5. Is the Glass-and-Paper Trick Really Necessary?
Not necessarily. In a regularly used sink with a functioning water trap, the plumbing already provides the primary protection against sewer gases.
The extra covering may be useful as a temporary physical barrier, but its effectiveness depends on how it is positioned and what problem you are trying to prevent. It will not repair a faulty trap, clear a blocked drain, or guarantee that insects cannot enter.
The most important step is maintaining the water seal in the plumbing and addressing any underlying problems.
Final Thoughts
The upside-down glass and paper trick is a simple household precaution intended to help cover a sink drain while a home is empty. Its potential benefit comes from providing an additional barrier—not from any special property of the glass itself.
Before your next vacation, make sure your drains contain water, remove food residue, and check for plumbing issues. Those steps are more important than relying on a makeshift cover.
Have you ever returned from vacation to find an unpleasant smell coming from a sink or bathroom drain? Share your experience in the comments, and let us know whether you have tried this household trick.
