If you’ve spent any time on social media lately, you’ve probably seen the travel tip that suggests placing a piece of paper over your sink drain and covering it with an upside-down glass before leaving for vacation. According to the posts, this simple trick can help prevent unpleasant odors, sewer gases, and even insects from entering your home while you’re away.
At first glance, the idea seems clever. It’s inexpensive, easy to do, and appears to have a practical purpose. But does it really work?
The answer is a little more complicated.
The concern behind the viral hack is based on a real plumbing principle, but the method itself isn’t the most effective way to protect your home. Understanding how your plumbing system works can help you decide whether this trick is worth trying—or whether there are better alternatives.
Why People Cover Their Drains Before Traveling
Most homeowners don’t think much about their sink drains until something goes wrong. However, every sink, bathtub, shower, and many floor drains have an important plumbing component hidden underneath called a P-trap.
The P-trap is the curved section of pipe located below the drain. While many people assume it’s simply there to catch debris or prevent clogs, its primary purpose is much more important.
The bend in the pipe holds a small amount of water at all times. This water creates a seal between your home’s plumbing and the main sewer system.
That water barrier helps prevent:
- Unpleasant sewer odors
- Sewer gases
- Small insects that may travel through drain systems
- Air from the sewer line entering your home
As long as water remains inside the P-trap, it continues doing its job.
What Happens When the Water Evaporates?
If a drain isn’t used for an extended period, the water inside the P-trap can slowly evaporate.
Once that protective water seal disappears, there’s nothing blocking odors or air from moving through the drain.
In some situations, homeowners may notice:
- Musty or unpleasant smells
- Sewer odors
- Gurgling noises
- Occasional insects appearing near unused drains
Fortunately, this doesn’t happen overnight.
In most homes, the water inside a P-trap lasts for several weeks before evaporation becomes a concern.
Do You Need to Worry During a Short Vacation?
For most people, the answer is no.
If you’re leaving for a weekend getaway, a business trip, or even a one- or two-week vacation, your P-traps will usually retain enough water to remain effective.
Evaporation tends to become more noticeable only when a drain goes unused for several weeks or even months.
That’s why this issue is more common in:
- Vacation homes
- Guest bathrooms
- Basement floor drains
- Laundry room drains
- Homes left vacant for extended periods
These drains may sit unused long enough for the water seal to gradually disappear.
Does the Paper and Glass Trick Actually Work?
The popular social media hack recommends placing a sheet of paper over the drain and setting an upside-down drinking glass on top before leaving home.
The theory is that covering the drain slows evaporation while creating a barrier against odors and insects.
While the idea sounds reasonable, it has several limitations.
First, a drinking glass rarely creates an airtight seal around a sink drain. Small gaps usually remain around the edges, allowing air to pass through.
Second, the paper itself doesn’t provide much protection. Humidity inside the home can cause it to soften, wrinkle, or shift out of place over time.
Finally, if the glass is accidentally bumped before you leave—or if someone uses the sink—the entire setup can easily be disturbed.
For these reasons, most plumbing professionals consider this more of a temporary household experiment than a dependable solution.
Better Ways to Prepare Your Drains Before Traveling
If you’re planning an extended vacation, there are several simple steps that offer much better protection than balancing a glass over your sink.
1. Run Water Through Every Drain
Before leaving, turn on every sink faucet for about 15 to 30 seconds.
Don’t forget:
- Bathroom sinks
- Kitchen sink
- Bathtub
- Shower
- Utility sink
- Basement floor drain (if accessible)
Also flush every toilet in the home.
This replenishes the water inside every P-trap, restoring the protective seal.
It’s one of the easiest and most effective maintenance tasks you can perform before traveling.
2. Cover Drains Properly
If you’ll be away for several weeks or longer, consider covering drain openings with something designed to fit securely.
Some good options include:
- Built-in sink stoppers
- Rubber drain plugs
- Silicone drain covers
- Flat silicone sink mats
- Plastic wrap secured around the drain opening (for temporary use)
The goal isn’t to create a permanent seal but rather to reduce airflow and slow evaporation while providing an additional barrier.
A Helpful Tip for Longer Vacations
Some experienced plumbers recommend adding a small amount of mineral oil after filling the P-trap with water.
Just a tablespoon poured into the drain creates a thin layer that floats on top of the water.
This layer slows evaporation considerably, helping the water remain inside the trap for a much longer period.
It’s important to use food-grade mineral oil, not cooking oil.
Cooking oils can become sticky over time and may contribute to unwanted buildup inside plumbing.
Mineral oil, on the other hand, remains stable and is commonly recommended for this purpose.
Other Plumbing Tasks to Complete Before Leaving
Preparing your drains is only one part of getting your home ready for vacation.
A few additional steps can help prevent unpleasant surprises when you return.
Empty the Garbage Disposal
Food particles left inside the disposal can create unpleasant odors over time.
Running the disposal with cold water before leaving helps flush away residue.
Take Out the Trash
Even small amounts of food waste can produce odors if left indoors for several days.
Removing kitchen trash before leaving keeps your home fresher.
Check for Leaks
Take a quick walk through your kitchen, bathrooms, laundry room, and basement.
Look for dripping faucets, leaking supply lines, or moisture around appliances.
Addressing small issues before leaving can help prevent larger problems later.
Consider Turning Off the Main Water Supply
If your home will be vacant for an extended period, many homeowners choose to shut off the main water valve.
While not required, this precaution can reduce the risk of water damage if a pipe or supply line were to fail while you’re away.
If you have an automatic sprinkler system or appliances that require water, be sure to consider those before shutting off the supply.
Separating Myth from Reality
The internet is full of creative household tips, and many of them contain a small amount of truth mixed with oversimplified advice.
The upside-down glass trick falls into that category.
The plumbing concern behind it is genuine.
P-traps do rely on water to block sewer gases and odors.
However, simply placing paper and a glass over the drain isn’t the most dependable solution.
Instead, a few minutes of basic preparation can provide much better results.
The Bottom Line
If you’re leaving home for only a few days, you probably don’t need to worry about your drains at all. The water inside your P-traps will almost certainly remain in place until you return.
For longer vacations or seasonal homes that may sit empty for several weeks, it’s worth taking a few simple precautions. Running water through every drain, covering drain openings with properly fitting stoppers, and using a small amount of mineral oil can help maintain the water seal that keeps odors and unwanted pests out of your home.
The best vacation preparations are often the simplest ones. Rather than relying on a viral social media hack, understanding how your plumbing works allows you to protect your home with proven methods that require only a few minutes before you lock the door and begin your trip.