Leak Prevention Checklist
A practical checklist for identifying plumbing leaks and moisture sources that create pest-conducive conditions. Informational only — consult a licensed plumber for any repair work.
Under-Sink Cabinet Inspection
Under-sink cabinets in kitchens and bathrooms are among the most common sites for undetected plumbing leaks. Check supply line connections at the valve and at the fixture; check the P-trap and drain connection for drips; look for water stains, soft spots in the cabinet floor, or mould growth indicating chronic moisture. The EPA WaterSense Fix a Leak Week resources provide a checklist for household leak detection. Supply line hoses with braided stainless steel sheathing are more durable than rubber hoses and should be replaced if showing any bulging or cracking.
Water Heater Drip Pan and Connections
Water heaters are a common source of chronic low-level moisture. Check the drip pan under the water heater for any standing water, which indicates a weeping T&P relief valve, a dripping inlet or outlet connection, or the beginning of tank failure. The area around the water heater base and the floor of the utility closet or basement area where it is installed should be dry. Check the temperature and pressure (T&P) relief valve annually — a licensed plumber can test it safely. The EPA WaterSense programme provides guidance on water heater maintenance and efficiency.
Toilet Supply Lines and Base Seals
Toilet supply lines (the braided hose connecting the shut-off valve to the toilet fill valve) are a common failure point. Inspect the connection at both ends for drips or mineral deposits indicating a slow weep. Check the toilet base for any movement (a rocking toilet suggests a failed wax seal, which can allow slow water seepage into the sub-floor). The water supply shut-off valve should turn freely — seized shut-off valves are a sign of age and should be replaced preventively. The NYC DEP water conservation guidance recommends annual inspection of all water-using appliances and fixtures.
P-Traps, Outdoor Hose Bibs, and Pipe Insulation
P-trap connections under sinks should be hand-tight and leak-free. Periodically pour water into infrequently used drains (guest bathrooms, utility sinks, floor drains) to replenish the P-trap water seal and prevent sewer gases and pests from entering. Outdoor hose bibs should be inspected for drips at the packing nut and where the pipe enters the building — a dripping exterior bib can wet the building exterior and create harborage conditions for pests near the foundation. Cold-water pipes in warm or humid areas should be insulated to prevent condensation drips. The CDC healthy water guidance covers building water system maintenance relevant to both water quality and pest exclusion.
Disclaimer
This checklist is an independent informational resource. Content cites EPA WaterSense, NYC DEP, and CDC as primary sources. Informational only — consult a licensed plumber for any repair work. Consult a licensed pest management professional for active pest problems. Last updated 2026-06-26.