Unblock a sink without chemicals
15–30 mins — four methods, no drain cleaner needed
A blocked sink is almost always grease, hair, or soap build-up in the trap. You can clear it yourself without chemicals. Try each method in order — most sinks are fixed by step two or three.
Last updated: March 2026
Only basic tools needed — most homes already have them.
Before you start
This guide works for kitchen sinks, bathroom basins, and en-suite sinks. A completely blocked drain (no water moving at all) is usually in the trap — the curved pipe directly under the sink. A slow drain is often earlier build-up in the trap or the pipe leading to it.
If multiple sinks or drains in the house are blocked simultaneously, the problem is in the main drain outside — this guide will not fix that.
No need to turn off the water supply for this job.
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Tools & materials
- ✓Kettle— for boiling water — the first thing to try
- ✓Bicarbonate of soda and white vinegar— most people have these at home
- ✓Bucket— to catch water when you remove the trap
- ✓Rubber gloves— for removing debris from the trap
- !Cup plunger— essential — a flat-cup plunger designed for sinks, not a toilet plunger
Want everything in one go?
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Start with boiling water
Boil a full kettle and pour it directly and slowly down the drain in two or three stages — a third of the kettle at a time, waiting 30 seconds between each pour. Why: most kitchen sink blockages are caused by grease and fat that have cooled and solidified in the trap or the first section of pipe. Boiling water melts the grease and carries it away down the drain. This works on around 40% of kitchen sink blockages and costs nothing. It does not work on hair blockages (bathrooms) or solid debris — but try it first before anything else. Do not use boiling water on PVC or acrylic basins — the heat can distort the material. Use hot tap water instead.
Most people get this done in under 5 minutes.
Where beginners go wrong
Using boiling water on plastic or acrylic basins. Boiling water can warp or crack acrylic. For anything that is not a stainless steel kitchen sink, use hot tap water — still effective on grease.
Not blocking the overflow or second drain when plunging. Air escapes through the overflow hole (the small hole near the top of the basin) or a second drain opening. Cover it with a wet cloth before plunging, otherwise you cannot build pressure.
Breaking the plunger seal on the upstroke. The suction on the upstroke is as important as the pressure on the downstroke. Keep the cup sealed against the drain throughout the full stroke cycle.
Skipping straight to drain cleaner. Chemical drain cleaners are corrosive, damage older pipes over time, and are hazardous to handle. They are also less effective on hair blockages than mechanical methods. Try all four steps first.
If none of these work...
If the trap is clear but the sink still drains slowly, the blockage is in the pipe inside the wall — use a drain snake pushed through the wall outlet to clear it
If multiple drains are blocked at the same time, the issue is the main drain outside the house — call a drain clearance company
If the drain smells but is not blocked, the trap may be dry (especially in a guest bathroom that is rarely used) — run the tap for 30 seconds to refill it
Cost breakdown
Recommended starter kit
Five tools that cover most home repairs.
- →Adjustable spannerAmazon·Screwfix
- →Screwdriver setAmazon·Screwfix
- →PTFE tapeAmazon·Screwfix
- →Spirit levelAmazon·Screwfix
- →Tape measureAmazon·Screwfix
Want everything in one go? Get it on Amazon
What you just learned
You know how sink drainage works — the trap, how blockages form, and the right sequence to clear them. These skills transfer to unblocking a bath, clearing a shower waste, and understanding your home's drain system from sink to street.
This unlocks:
⚠️ Watch out if you rent
You are generally allowed to unblock your own sink — it is maintenance rather than a modification. If the blockage is in the main drain (multiple sinks affected), report it to your landlord in writing as it is their responsibility to arrange clearance.