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UK USA
us Home & property emergencies sewer smell from one drain • sewage odor in one bathroom • rotten egg smell drain • drain smells after running water • sink smells like sewer gas • shower drain sewer smell • bathtub drain smells • floor drain smells • smell near bathroom sink • intermittent sewer gas smell • one drain smells not whole house • bad smell from sink overflow • sewer gas smell indoors • p-trap smell problem • trap seal dried out • plumbing vent smell • drain blockage smell • gurgling drain with odor • under sink smells like sewage • headache nausea near drain

What to do if…
you find a strong sewer smell coming from one specific drain even after running water

Short answer

Assume sewer gas is entering the room: ventilate right now, avoid mixing drain chemicals, stop using that fixture, and arrange a landlord/plumber repair if the smell doesn’t clear quickly.

Do not do these things

  • Don’t keep “testing” the smell up close if it’s strong or you feel sick — step back into fresh air.
  • Don’t pour in repeated or mixed chemicals (especially bleach with acids or ammonia products).
  • Don’t try to snake/dismantle plumbing if you’re renting or unsure — you can worsen leaks or break trap seals.
  • Don’t ignore warning signs like gurgling, slow draining, or water backing up.
  • Don’t confuse sewer odor with a fuel gas leak: if you’re unsure, leave the area for fresh air and contact your gas utility (or 911 if there’s immediate danger).

What to do now

  1. Get fresh air in the room. Open windows, run the bathroom fan if it vents outdoors, and keep the door closed.
  2. Confirm it’s truly one drain (no deep sniffing). Briefly check other drains (kitchen sink, other bathroom, laundry) without lingering. If multiple drains smell or drains are backing up, treat it as a larger blockage/vent/sewer issue and jump to step 7.
  3. Check the “trap seal” problem points (no tools).
    • Sink overflow: If it smells strongest at the overflow opening, the overflow channel may be the culprit.
    • Shower/tub drain: Hair and sludge near the strainer can stink even when water runs.
    • Floor drain (basement/utility): Trap seals can dry out and let sewer gas in.
  4. Clean the overflow and drain opening safely.
    • Scrub the sink overflow and the area around the stopper/strainer using hot water + dish soap and a small brush.
    • Rinse with hot water. Avoid chemical “cocktails.”
  5. Check for leaks under/around the fixture.
    • Under the sink: look/feel for dampness, drips, staining, or smell strongest in the cabinet.
    • Around the toilet base (even if the smell seems “nearby”): check for any seepage or persistent odor in the room.
  6. Stop using the fixture if the smell persists.
    • Put the stopper/plug in (if available), keep ventilating, and avoid running water there until it’s inspected.
  7. Contact the right help (USA).
    • If you rent: notify your landlord/property manager promptly (odor + suspected sewer gas/leak/blockage). Ask for a licensed plumber visit.
    • If you own: schedule a licensed plumber or drain specialist, especially if you have slow drains, gurgling, or recurring odor after cleaning.
    • If it seems like a sewer line issue (multiple fixtures, backups, sewage outside, neighbors affected): contact your city/county sewer utility (or your private septic service if you’re on septic).
  8. If anyone has symptoms, treat it as fresh-air + medical guidance.
    • Headache, dizziness, nausea, breathing/eye/throat irritation: move to fresh air.
    • If someone collapses, has trouble breathing, has a seizure, or can’t be awakened: call 911.
    • For advice on possible exposure (even if it’s not an emergency), call Poison Control / Poison Help: 1-800-222-1222 for free, confidential guidance.

What can wait

  • You don’t need to pinpoint whether it’s venting, siphoning, a failed toilet wax ring, a partial clog, or a cracked pipe — that’s what the inspection is for.
  • You don’t need to do major DIY today if you can isolate the fixture and ventilate.
  • You don’t need to decide on big repairs immediately; start with documenting the location, timing, and any backup/slow-drain signs for the plumber or property manager.

Important reassurance

This is a common household problem and it’s usually fixable once the entry point for sewer gas (trap/seal/leak/blockage/venting) is found. You’re doing the right thing by treating it cautiously and getting it addressed rather than trying to “chemical” it away.

Scope note

These are first steps to reduce risk and prevent escalation. If the odor continues after basic cleaning/ventilation, professional inspection is the right next move.

Important note

This is general information, not a diagnosis or a substitute for professional plumbing or medical advice. If you suspect a fuel gas leak, prioritize safety and follow your utility’s emergency instructions (use 911 if there’s immediate danger). If symptoms occur or the smell is overpowering, prioritize fresh air and urgent medical help.

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