Checklist • Dec 15, 2025 • 8 min read

Under-sink smell checklist: P-trap, disposal, and hidden leaks

Under-sink smells usually come from moisture, food residue, or a dry P-trap. This checklist helps you narrow it down without risky DIY.

Michael Rivera

Property maintenance specialist with 12+ years helping renters handle everyday fixes.

Important: These guides focus on low-risk, reversible steps. If your lease forbids a modification (or the task involves gas/electrical/structural work), stop and contact maintenance.

Under-sink plumbing showing P-trap and drain pipes — Under the sink: the curved P-trap holds water to block sewer gases. Check here first for leaks or dry traps.

Fast sniff test (where is it strongest?)

Cabinet wood / floor: musty smell often means moisture.
Drain area: sewer-ish smell can mean P-trap issues.
Garbage disposal: sour/rotting smell is usually residue.

Checklist

Check	What you see/smell	Next action
Look for moisture	Damp cabinet, swelling, dark stains	Photo + report to maintenance
P-trap area	Sewer smell near pipes	Run water 30–60 sec; smell improves = trap was dry
Disposal splash guard	Sour smell, slime	Clean guard + flush with dish soap and water
Trash can / recycling	Smell concentrated there	Wash bin; use liners; ventilate

Stop signs (call maintenance)

Any active drip or wetness that returns after drying.
Strong sewer smell that persists after running water.
Visible mold growth on porous cabinet material.