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uk Home & property emergencies sink backing up • bath backing up • bathtub backing up • dirty water rising • wastewater coming up drain • sewage smell in bathroom • drain overflowing indoors • sink gurgling then overflow • grey water backing up • black water in bath • sudden drain backflow • water coming up plughole • multiple drains backing up • toilet bubbling when sink runs • shared drain blockage • sewer flooding inside home • kitchen sink overflow • bathroom flood from drain • blocked drain emergency • wastewater in shower tray

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

Short answer

Stop using all taps and appliances that drain water, keep people and pets away from the contaminated water, and shut off the water supply if the level is still rising.

Do not do these things

  • Don’t keep “testing” by running taps, flushing toilets, or running the washing machine/dishwasher.
  • Don’t wade into the water if it’s near sockets, extension leads, appliances, or boiler controls.
  • Don’t try chemical drain cleaners—backed-up dirty water can splash and chemicals can make it more dangerous.
  • Don’t start plunging or rodding if the water is already high/dirty or more than one drain is affected (it can force sewage out and spread contamination). If it’s a single slow-draining sink with only a small amount of clean-ish water, a plunger may help—but stop immediately if dirty water starts rising.
  • Don’t mop it through the house or into carpets if you can avoid it.
  • Don’t assume it’s “your pipe” if more than one drain is affected—this can indicate a shared drain/sewer issue.

What to do now

  1. Stop all water use immediately. Turn off taps and tell everyone in the property not to flush toilets or run anything that drains.
  2. Keep everyone away from the area. Close the bathroom/kitchen door if you can. Keep children and pets out.
  3. If it’s near electrics, make it electrically safe from a dry place. If you can safely switch off power to the affected area at the consumer unit without stepping in water, do so. If you can’t do this safely, stay out and wait for professional help.
  4. Shut off your water supply if the level is still rising (or someone might accidentally use water). Turn the inside stop valve/stopcock clockwise to reduce the chance of more water being added to the blocked system.
  5. Contain what you can without touching it. Put towels around the threshold/door to slow spread. If safe, place a bucket or shallow tray to catch overflow at the edge.
  6. Work out whether it may be a sewer/drain issue (not just one fixture). If more than one drain is backing up (e.g., bath + sink, or toilets gurgling), treat it as a drain/sewer problem, not a simple plughole blockage.
  7. Call the right party:
    • If you rent: contact your landlord/letting agent immediately (use the emergency repairs route if provided).
    • If you own/occupy and it’s just one fixture: contact a drainage plumber.
    • If multiple fixtures are affected, neighbours are affected, or an outside drain/manhole (inspection chamber) is overflowing: report it to your water and sewerage company (they handle public sewers and some shared/lateral drains).
  8. If anyone’s safety is at risk, escalate. If the flooding is putting someone at immediate risk (for example, a vulnerable person trapped, or you cannot make the area safe around electrics), call 999.
  9. Document quickly, then step back. Take a few photos/videos of the source and water level for insurance/landlord, then leave the area closed off.

What can wait

  • You do not need to decide right now who is “to blame” (private drain vs public sewer).
  • You do not need to start disinfecting immediately—first stop the rise, keep people safe, and get the right help lined up.
  • You do not need to throw anything away yet unless it’s actively soaking and spreading contamination.

Important reassurance

This is a common and upsetting situation—your job in the first minutes is simply to stop adding water, reduce exposure, and prevent it spreading. You can sort cleanup and responsibility once the flow has stopped.

Scope note

These are first steps to stabilise the situation and reduce harm. Cleanup, drying, and any insurance or responsibility questions come after the immediate risk is under control.

Important note

This is general information, not professional advice. If you think sewage has entered living areas, treat the water as contaminated and prioritise safety (especially around electricity) and professional help.

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