PanicStation.org
UK USA
uk Home & property emergencies

What to do if…
a sink or bathtub backs up and dirty water starts rising

Produced and maintained by PanicStation.org Published: Last reviewed: Editorial policy UK guide

Short answer

Stop using all taps, toilets, and appliances that drain water. Keep people and pets away from the dirty water, and shut the inside stop valve only if it is safe and you need to prevent more household water being added.

Do not do these things

  • Don’t keep testing the problem by running taps, flushing toilets, or using a washing machine or dishwasher.
  • Don’t step into dirty water if it is near sockets, extension leads, appliances, boiler controls, or the consumer unit.
  • Don’t touch switches, plugs, cables, or appliances while standing in water.
  • Don’t use chemical drain cleaners in backed-up dirty water; splashes can make the situation more dangerous.
  • Don’t plunge or rod the drain if the water is dirty, high, rising, or more than one drain is affected.
  • Don’t mop dirty water through the house or into carpets if you can avoid it.
  • Don’t assume it is only your pipe if more than one drain, toilet, bath, sink, shower tray, or outside chamber is affected.

What to do now

  1. Stop all water use immediately. Turn off taps and tell everyone in the property not to flush toilets, run sinks, use the bath or shower, or start any appliance that drains water.
  2. Keep people and pets out of the area. Close the kitchen or bathroom door if you can. Treat the water as contaminated, especially if it smells of sewage, is black or grey, or is coming up through a plughole.
  3. Make the area electrically safer only from a dry place. If you can reach the consumer unit without stepping in water or touching wet fittings, switch off power to the affected area or the whole property. If you cannot do that safely, stay out of the area and wait for professional help.
  4. Use the inside stop valve if it helps prevent more water entering the drains. Turn it clockwise if the water is still rising or someone might accidentally use water. This may not stop sewer water already backing up, but it can stop your property adding more.
  5. Slow the spread without touching the dirty water. Put old towels at the doorway or edge of the room if you can do this from dry ground. Do not try to deep-clean now.
  6. Check whether it looks like one fixture or a wider drain problem. A single sink backing up may be a local blockage. A bath plus sink backing up, toilets bubbling, shower trays filling, sewage smell, or an outside inspection chamber overflowing usually means a wider drain or sewer issue.
  7. Contact the right help. If you rent, contact your landlord, letting agent, housing association, or emergency repairs line. If you own and only one fixture is affected, contact a drainage plumber. If several fixtures are affected, neighbours are affected, or an outside drain or chamber is overflowing, contact your local wastewater or sewerage provider.
  8. Escalate if there is immediate danger. Call 999 if someone is trapped, at immediate risk, or you cannot keep people away from water near electrics.
  9. Take quick evidence, then leave it alone. From a safe dry place, take photos or a short video of the water level, the plughole, and any affected items for your landlord, insurer, plumber, or wastewater provider.

What can wait

  • You do not need to decide now who is responsible for the drain or sewer.
  • You do not need to prove whether it is a private drain, shared drain, lateral drain, or public sewer before asking for help.
  • You do not need to start disinfecting while the water is still rising.
  • You do not need to throw belongings away immediately unless moving them safely prevents dirty water spreading.
  • You do not need to argue about costs in the first few minutes; focus on stopping water use, staying out of contamination, and getting the right help contacted.

Important reassurance

This is unpleasant and stressful, but the first job is small: stop adding water, stay away from contamination and electrics, and contact the person or organisation that can clear the blockage. Responsibility and cleanup can be dealt with after the water has stopped rising.

Scope note

These are first steps only. Cleanup, drying, repairs, insurance, tenancy duties, and responsibility for drains or sewers may need help later from a drainage professional, landlord, insurer, wastewater provider, local authority, or advice service.

Important note

This is general information, not legal, medical, financial, therapeutic, or other professional advice. If dirty water has entered living areas, treat it as contaminated and prioritise safety, especially around electricity.

Additional Resources

Closely connected guides that may be useful during the same situation or its immediate aftermath.

About this guide

This guide was produced and is maintained by PanicStation.org using its published editorial process. Official and specialist sources are checked where relevant, and AI-assisted tools may be used for drafting, organisation, and consistency checks. The site operator remains responsible for publication, revision, and removal decisions.

Support us