The Real Deal on Covering Your Sink Before Vacation

There’s a strange vacation trick making the rounds online: put a sheet of paper over your sink drain, then place a glass upside down on top of it before leaving home.

It looks oddly specific, which naturally makes people wonder: What is the glass supposed to do, and is this actually necessary?

The idea is connected to a real plumbing feature called the P-trap. The curved pipe underneath your sink normally holds water, creating a barrier that helps keep sewer odors from coming back through the drain. If a drain sits unused long enough, that water can evaporate and the trap can eventually dry out.

But the paper-and-upside-down-glass trick is not the important part. There are simpler and more dependable ways to prepare your drains before a trip.

Why Your Sink Has a P-Trap

If you look underneath most kitchen or bathroom sinks, you’ll see a curved section of pipe. That curve is the P-trap.

It isn’t there by accident.

After water goes down the drain, some remains inside that curved section. This water forms what plumbers call a water seal, which helps block sewer gases from traveling back into the house.

The same basic principle applies to many other drains, including bathroom sinks, showers, tubs, and some floor drains.

The problem comes when a drain isn’t used for a long time. Water in the trap can gradually evaporate. Once the water seal disappears, unpleasant odors can make their way into the room.

That is the real reason people become concerned about covering drains before a long vacation.

So What Is the Upside-Down Glass Supposed to Do?

The glass-and-paper setup is essentially being used as a temporary cover over the drain opening.

The theory is understandable: if the opening is covered, it may provide an additional physical barrier against things coming through the drain.

But there is an important distinction.

Covering the opening does not replace the water inside the P-trap.

If the trap dries out, the paper and glass aren’t creating the same dependable plumbing seal that the water-filled trap provides. A sheet of paper can also become damp, shift out of position, or leave gaps around the drain.

So while the viral trick isn’t completely nonsensical, it is being presented as more important than it really is.

What Should You Actually Do Before Leaving?

For an ordinary vacation, you don’t need to turn your kitchen sink into a science experiment.

A few simple steps make more sense.

1. Clean the sink and drain

Before leaving, rinse away food particles and wipe out the sink.

If you have a garbage disposal, clean the area around the opening as well. Food residue left behind can contribute to unpleasant smells while you’re away.

2. Run water down the drain

Let some water run through the sink before you leave.

This helps ensure the P-trap has water in it when you head out. The same principle is useful for other rarely used drains around the house. Regularly adding water to infrequently used traps is a standard way to prevent dry-drain odors.

3. Use the sink’s drain stopper if you have one

If your sink has a proper stopper or drain cover, closing it provides a much more sensible physical barrier than balancing a sheet of paper underneath an upside-down glass.

It can also help keep debris and insects from reaching the drain opening.

For homes where pest activity is already a problem, tightly covering drains can be one part of a broader prevention strategy.

4. Don’t forget the other drains

The kitchen sink isn’t necessarily the drain you should worry about most.

A guest bathroom sink, rarely used shower, bathtub, or floor drain may sit untouched for much longer.

If you have drains that are rarely used, make sure their traps aren’t dry before leaving.

What About Sewer Smells When You Get Home?

If you return from vacation and notice a strong sewer-like smell, don’t automatically assume you need a powerful drain cleaner.

First, consider whether a rarely used drain may have a dry trap.

Adding water to the affected drain can restore the water seal if evaporation was the cause. If the odor continues even after the trap has been refilled, there may be another plumbing problem that needs attention.

A persistent odor can also come from buildup, a plumbing connection, ventilation problems, or another issue that isn’t solved simply by covering the drain.

Can You Still Use the Paper-and-Glass Trick?

You can understand why someone might try it, but there is no good reason to treat it as a must-do vacation ritual.

If your goal is to protect the drain opening, a proper stopper or drain cover is more practical.

And if your goal is to prevent sewer odors, the key thing is making sure the P-trap remains filled with water.

Those are two different jobs.

The viral setup combines them into one unusual-looking trick, which probably explains why the photo gets so much attention.

What If You’re Leaving for Several Weeks?

A longer absence deserves a little more attention than a short weekend trip.

Check the drains that aren’t regularly used and make sure their traps contain water before you leave. This is especially worth remembering for guest bathrooms and floor drains that may go unused for long periods.

If you have a drain that repeatedly dries out despite being filled, there may be a plumbing or evaporation issue worth discussing with a qualified plumber.

For an extended absence, a professional can also advise you about appropriate products designed to protect drain traps without relying on improvised household materials.

One More Thing: Take Out the Trash

Before locking the door, don’t forget the obvious sources of kitchen odors.

Take out the garbage, empty food scraps, rinse the sink, and clean any obvious residue around the drain.

A covered drain won’t solve a smell caused by food sitting in the garbage can or disposal.

A few minutes of cleanup before leaving can make a much bigger difference when you return.

The Bottom Line

That upside-down glass sitting over a sheet of paper looks mysterious, but the real plumbing science behind the idea is much simpler.

Your P-trap is the important part.

The water held inside it creates a barrier that helps keep sewer gases from entering your home. When a drain remains unused for a long time, that water can evaporate and the trap can dry out.

Before vacation, clean the sink, run water through the drain, check rarely used drains, and use proper drain stoppers where appropriate.

You can skip the complicated-looking glass trick. The simplest solution is usually the one that makes the most sense: keep the trap filled and the drain clean.