One sink or basin
Usually the trap, plug waste, pop-up mechanism or first section of waste pipe. Hair, toothpaste, soap scum and scale are common.
Emergency plumbing advice
Blocked sink, toilet, washing machine waste or drain?
Before pouring anything down the pipe, work out what type of blockage you have. Hair, fat, limescale, washing machine solids and drain blockages all behave differently.
Reviewed by Pompey Plumb Ltd. Last reviewed 24 June 2026.
- Stop using the blocked fixture before it overflows.
- Check if other sinks, baths or toilets are affected.
- Do not mix drain chemicals, bleach, acids or caustic products.
- Keep children and pets away from wastewater or chemicals.
- Call for help if sewage backs up or several fixtures are blocked.
Quick diagnosis
Start by finding where the blockage is
Bath or shower
Often hair, soap residue and shallow waste runs. A trap clean, wet vac or mechanical clearing may beat chemicals.
Toilet
Could be too much paper, wipes, sanitary products, toys, pan connector problems or a soil pipe issue.
Several fixtures
If more than one fixture is affected, think shared waste pipe, soil stack, gully, inspection chamber or external drain.
Photo guide
Common blockage situations
Standing water in a sink
If only this fixture is affected, the blockage is often close by in the trap, plug waste or first waste pipe.
Appliance waste spigot
Washing machine and dishwasher wastes often block at the spigot or trap connection, especially where residue builds up.
Poor waste layout
Long runs, bad falls, awkward bends and poor fittings can cause repeat blockages even after the pipe is cleared.
Corrected pipework
Sometimes the fix is not stronger chemical. It is cleaning, replacing or improving the waste pipe layout.
Faulty waste fittings
A missing seal or poor connection can leak and collect debris. This is a fitting problem, not just a blockage.
Toilet waste problems
A toilet blockage may be in the pan, the pan connector, the soil pipe or the outside drain.
Inspection chamber full
If an outside chamber is full, stop using water where possible. This is usually a drain or sewer route problem.
After clearing
Once clear, the cause still matters. Wipes, fat, roots, broken pipework or bad falls can make the problem return.
Blockage types
Different blockages need different treatment
Hair, soap and skin residue
Common in basins, baths and showers. Traps, waste outlets and mechanical clearing are often the first answer.
Fat, oil, grease and food waste
Common in kitchen wastes. Hot water can move fat further along before it cools and sets again.
Limescale and calcified traps
Hard-water scale can turn a basin trap into a solid restriction. Caustic drain cleaners are not descalers.
Washing machine solids
Grey or white deposits from detergent, fabric conditioner, lint, skin oils and scale can harden in spigots and waste pipes.
Wipes and non-flushables
These do not break down like toilet paper and can combine with fat to block drains, pumps and sewers.
Bad pipework or poor falls
If the pipe run is wrong, the blockage may keep coming back until the layout is corrected.
Long pipe extensions or solid underground blockages
These often need drainage specialists with the right equipment, such as rods, jetting, CCTV inspection or excavation.
Basin traps
Calcified traps can need digging out
A basin trap can become packed with hard scale, toothpaste, soap scum, hair and sludge. In hard-water areas, the mineral part can become so solid that it has to be broken out or the trap replaced.
- Caustic or alkaline drain cleaners can attack grease and hair, but they do not dissolve limescale properly.
- In an already restricted trap, repeated alkaline products can fail to clear the mineral deposit and may leave a harder, more stubborn mass.
- If a trap is calcified, mechanical cleaning, replacement or a suitable descaling approach is usually more logical than more caustic.
- If any drain chemical has already been used, tell the plumber before they open the trap.
Washing machines
Washing machine waste can be its own problem
Washing machine and dishwasher wastes can build up solids that are different from a normal kitchen fat blockage. Detergent, fabric conditioner, lint, skin oils, low-temperature wash residue and limescale can form hard deposits in spigots and waste pipes.
- Because many of these deposits are alkaline or mineral-heavy, a normal alkaline drain cleaner may be the wrong chemistry.
- A plumber may use specialist acidic cleaner after checking the pipework and what has already been poured down.
- Regular machine maintenance helps prevention: use products such as Calgon or a suitable descaler as directed, especially in hard-water areas.
- Occasional hot maintenance washes and using the right detergent amount can reduce sludge before it reaches the waste pipe.
- Maintenance products help prevent build-up. They are not a reliable fix once the spigot or waste pipe is already blocked.
Internet advice
Bicarb and vinegar is usually overrated
Bicarbonate of soda and vinegar fizz because an acid and a base are reacting. The fizz can look impressive, but the mixture largely neutralises itself and is usually weak against a real blockage.
- It may freshen a plughole or disturb light slime close to the surface.
- It will not remove most fat, scale, washing machine solids, wipes, toys or bad pipework.
- The same applies to many home remedies: they do not diagnose the cause.
Chemical safety
Do not keep adding stronger products
Drain unblockers can be strongly acidic or strongly alkaline. They can burn skin, damage eyes, react with other cleaners and leave dangerous liquid trapped in the pipe.
- Never mix bleach, drain unblocker, acid, caustic soda, toilet cleaner or limescale remover.
- Do not use drain chemicals in a toilet unless the product specifically says it is safe for toilets.
- Do not plunge or dismantle a trap full of unknown chemical without proper precautions.
- If one product has not worked, stop and get advice instead of adding another.
Portsmouth and Southsea
When to call a plumber, drainage company or water company
One sink, basin, bath or shower is slow or blocked
Usually a plumbing waste issue. A plumber can check the trap, waste pipe and fittings.
Washing machine waste backs up into the sink or cupboard
Stop using the machine. The spigot, trap or appliance waste may be blocked.
Toilet is blocked but other fixtures drain normally
Could be the pan, pan connector or local soil connection. Stop flushing repeatedly.
Several fixtures are affected, or water rises elsewhere when you drain a bath or flush
Likely shared waste, soil stack, gully or drain. This may need drainage equipment.
Long underground runs, extensions or a solid drain blockage
Use a drainage specialist. These jobs can need jetting, CCTV tracing, drain rods or excavation rather than standard plumbing tools.
Outside inspection chamber is full or sewage is backing up
Stop using water where possible and contact a drainage specialist or Southern Water depending on responsibility.
Several nearby properties are affected
This may be a public sewer issue for the water company. They may still ask you to get a plumber or drainage contractor to confirm it is not just your private drain.
There are chemicals in the blocked pipe
Tell anyone attending before they open the waste. This changes the risk of the job.
Blocked and not sure what type it is?
Take a clear photo of the fixture, pipework under it and any outside chamber if it is safe, then call or request an appointment.
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