Before leaving for a much-anticipated vacation, most people draw up a mental checklist to make sure their home stays safe and problem-free in their absence. Common tasks include checking that all doors and windows are securely locked, unplugging appliances to avoid electrical hazards or wasted energy, clearing out perishables so you’re not greeted by moldy food on your return, and adjusting thermostats or timers to maintain comfort and security. Many even ask a trusted neighbor to watch for deliveries or water plants. Yet despite this thorough preparation, one crucial detail is often overlooked: the sink drain. Because a drain is such an ordinary and rarely noticed part of daily life, it tends to be forgotten among the more obvious items on departure checklists. Nevertheless, this mundane feature can become a surprising source of trouble—especially odors and pest entry—that greets you the moment you step back into your home after days or weeks away.

The reason a forgotten drain can become problematic lies deep within the plumbing system, in a part called the P-trap (or U-shaped pipe) located beneath every sink. This bend in the pipe is designed to hold a small reservoir of water that acts as a barrier against sewer gases and pests. Under normal use, daily water flow keeps this reservoir topped up, maintaining the seal that keeps unwanted air and life below ground from entering your living space. However, when a home is unused for an extended period, especially in warm, dry conditions, this water can slowly evaporate. As the water level drops, the protective seal weakens and eventually disappears altogether, leaving a direct pathway from the sewer system into your home. With that barrier gone, both foul odors and small insects like drain flies, gnats, ants, and cockroaches can find an easy route inside. These creatures are naturally drawn to warm, moist, and sheltered spaces—conditions that an unoccupied home and unused pipes uniquely provide.

When a P-trap dries out, air from the sewer system—containing gases such as hydrogen sulfide, methane, and other volatile organic compounds—can rise through the drain and permeate your living areas. The result is a stale, sulfur-like smell that can settle into fabrics, carpets, and furniture and be difficult to eliminate without thorough airing and cleaning. In some buildings, particularly older ones with shared stacks or extensive plumbing networks, the problem can be worse because insects and odors travel easily through interconnected drains. Professional plumbers and home maintenance guides regularly stress the importance of keeping trap water in place precisely to prevent these unwelcome outcomes.

Thankfully, preventing these issues is simple and inexpensive. Plumbers and home maintenance experts often recommend a low-tech but effective method: covering the sink drain before you leave with a piece of absorbent material (like a paper towel) topped with an upside-down glass or cup. This technique works by reducing airflow directly over the drain opening, thereby slowing the evaporation of the water within the P-trap and creating a physical barrier that blocks odors and pests even if the trap water does diminish. The paper or towel helps absorb any residual moisture and fills small gaps, while the inverted glass serves as an inexpensive but sturdy cover that stays in place regardless of temperature or humidity changes. Because many pre-departure checklists rarely mention specialized tools, this method stands out: it uses items most households already have—paper towels and drinking glasses—making it a very accessible solution.

Beyond simply covering the drain, homeowners who want to take even more thorough steps can incorporate a pre-vacation sink ritual into their routine. This could start with cleaning the sink thoroughly to remove food particles, soap residue, grease, or other organic matter that might contribute to odors or attract insects. Pouring hot water or natural cleaners like white vinegar down the drain before sealing can help dissolve lingering residue and reduce potential smells. After rinsing and drying the sink, placing a paper towel and inverted glass over the drain seals the opening and signals visually that the sink has been prepared for vacation. While these additional cleaning steps are not strictly required, they reduce the amount of organic material in the drain before the house sits unused, making odors less likely to develop and lowering the overall bacterial load near the plumbing entry points.

Some travelers might wonder why they can’t just rely on the sink’s built-in stopper to protect the drain during their absence. In everyday use, stoppers serve well for holding water or soaking dishes, but they are not designed as long-term seals. Rubber gaskets can deform with heat and humidity, and mechanical linkages can loosen or shift, creating gaps that allow air and pests to enter. Unlike a stopper, an inverted glass placed over the drain does not rely on internal components or compression; its weight alone blocks the opening simply and reliably. Plumbers often favor these kinds of low-tech solutions because simple passive barriers can outperform more complex mechanisms when the goal is to block air and pests rather than hold water. This straightforward strategy withstands environmental fluctuations and eliminates many of the failure points associated with mechanical stoppers.

Taking a few minutes to prepare your drains before vacation might seem like a small detail, but its benefits can be substantial. Arriving home to a clean, odor-free environment contributes significantly to a smooth transition back into everyday life after travel. By blocking drains and ensuring that plumbing is as protected as possible before leaving, you reduce stress, prevent unexpected cleanup tasks, and contribute to a healthier indoor environment. Small maintenance habits—like ensuring that traps remain filled or covered—can prevent bigger problems later, illustrating how attention to minor details yields outsized comfort and peace of mind. With these preparations in place, you can enjoy your trip without worry and return to a fresh, welcoming home rather than an immediate cleanup mission.