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uk Home & property emergencies sewer smell from one drain • foul smell from drain • rotten egg smell drain • drain smells after running water • sink smells like sewage • shower drain sewer smell • bath drain smells • floor drain smells • smells worse at night • intermittent drain smell • one drain smells not whole house • bad smell from plughole • sewer gas smell indoors • p-trap smell issue • u-bend smell • drain trap not holding water • plumbing vent smell • blocked drain smell • gurgling drain with smell • drain overflow smells

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

Short answer

Treat it as “sewer gas getting into the room” until proved otherwise: ventilate, avoid mixing chemicals, and stop using that fixture until you’ve checked the obvious trap/overflow points and arranged a repair if needed.

Do not do these things

  • Don’t ignore it or “get used to it” — a persistent sewer smell can mean a failed trap seal, leak, or blockage.
  • Don’t pour multiple cleaners down the drain (especially bleach plus anything acidic or ammonia-based) to “burn the smell out”.
  • Don’t dismantle pipework if you’re renting or unsure what you’re doing — you can worsen a leak or dislodge seals.
  • Don’t keep “testing” the smell up close if it’s strong or you feel unwell — step back into fresh air.
  • Don’t confuse this with a gas leak: if you’re unsure whether it’s sewage or gas, treat it as gas and call the National Gas Emergency Service on 0800 111 999.

What to do now

  1. Ventilate the room immediately. Open windows and keep the door shut to limit spread to the rest of the home.
  2. Do a quick “is it only this drain?” check (no deep sniffing). Briefly check other rooms/drains without lingering or inhaling deeply. If multiple drains smell, you notice gurgling/backing up, or anyone feels unwell, stop investigating and jump to step 8.
  3. Check the easy water-seal points (without tools).
    • For a sink: check the overflow hole (near the top of the basin). If it smells strongest there, the overflow channel may be dirty.
    • For a shower/bath: check the waste/grate area for trapped hair/sludge.
    • If it’s a floor drain (utility/garage), the trap seal can dry out and let odours in.
  4. Clean the overflow/waste area safely.
    • Use hot water + washing-up liquid and a small bottle brush/old toothbrush for the overflow and around the waste.
    • Rinse with hot water. (Avoid aggressive chemical mixes.)
  5. Look for signs of a leak or a failing seal.
    • Check under the sink/basin for damp patches, drips, staining, or a smell strongest inside the cupboard.
    • If you can see the trap, look for obvious looseness or a displaced washer (don’t force it).
  6. Stop using that fixture if the smell persists.
    • Put the plug in (if there is one) and keep the room ventilated.
    • If you must use water in the room, use a different fixture if possible.
  7. Decide who to contact based on where the problem likely is (UK).
    • If you rent: report it to your landlord/letting agent as a repair issue (persistent sewer smell from one drain).
    • If you own and it seems internal to your property: book a qualified plumber/drain specialist.
    • If you suspect a shared/public sewer issue (multiple homes affected, smell from a manhole/inspection chamber outside, outside sewage/overflow): contact your water and sewerage company to report it.
    • If the smell is coming from a neighbour/business site rather than your own drainwork: report it via your local council environmental health route.
  8. If anyone feels unwell, treat it as a health issue and get fresh air. Headache, nausea, dizziness, eye/throat irritation: move to fresh air and seek urgent advice via NHS 111 (or 999 for life-threatening symptoms).

What can wait

  • You don’t need to identify the exact plumbing fault right now (trap siphoning, venting issues, failed seals, partial blockage).
  • You don’t need to “fix it yourself” today if you can ventilate and avoid the affected drain until help arrives.
  • You don’t need to argue responsibility immediately — report it promptly (with the location, when it happens, and whether neighbours are affected) and keep notes/photos of any damp.

Important reassurance

A single-drain sewer smell is a common, fixable plumbing problem. Taking a calm “ventilate + avoid chemical mixing + stop using that drain + report/book repair” approach is the safest way to prevent it getting worse while you get it sorted.

Scope note

This is first-steps only: it’s meant to stabilise the situation and help you choose the right contact (landlord/plumber/water company/council). Diagnosis and repair are for a competent professional if the simple checks don’t resolve it.

Important note

This is general information, not a professional diagnosis. If you suspect a fuel gas leak, prioritise safety and call the National Gas Emergency Service (0800 111 999). If symptoms occur or the smell is overpowering, prioritise fresh air and urgent medical advice.

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