You’re dealing with a bathroom sink that won’t drain, while the kitchen sink works normally ,frustrating, but usually very fixable.
Water sits or drains very slowly in the bathroom sink only.
The kitchen sink drains perfectly fine.
Is this your problem?
What to do
This almost always means a local blockage, not a main drain issue.
Step 1: Check the plughole and overflow
Hair, soap, toothpaste and skin oils build up here fast.
Remove the plug and pull out any visible debris.
Pour a kettle of hot (not boiling) water down the drain.
Step 2: Clean the overflow channel
Use a thin brush, cable tie, or straightened coat hanger.
Push it into the overflow hole (near the top of the sink).
You’ll often pull out black sludge that stops air flow.
Step 3: Unscrew and clean the trap (U-bend)
Place a bowl underneath.
Hand-unscrew the plastic nuts (no tools needed).
Empty, rinse, and refit tightly by hand.
This is safe DIY for most UK homes.
Step 4: Try plunging (if still slow)
Block the overflow hole with a damp cloth.
Use a standard sink plunger — short, sharp pushes.
This often clears soft soap blockages.
The sink drains slowly only at certain times, or gurgles.
The sink drains slowly only at certain times, or gurgles.
Is this your problem?
What to do
You may have a partial blockage further along the bathroom waste pipe.
Step 1: Use a manual drain snake
Insert it through the plughole or trap.
Twist gently — don’t force it.
Step 2: Avoid chemical drain cleaners
UK bathroom pipes are often older plastic.
Chemicals can soften seals and cause leaks later.
Stop here and call a plumber if water backs up quickly or you see leaks after refitting the trap.
The bathroom sink drains slowly and smells, but no visible blockage.
Is this your problem?
What to do
This is usually biofilm build-up inside the pipe.
Step 1: Pour half a cup of washing-up liquid down the drain.
Step 2: Follow with hot water after 10 minutes.
This breaks down grease safely.
Repeat once a month to prevent return.
Outside drain smell problem can also occurred so at last check this also.
FAQs
Can I use boiling water?
No. Many UK sinks use plastic traps and seals. Very hot water can warp them. Use hot tap water or a cooled kettle.
Does this mean my main drain is blocked?
No. If the kitchen sink is fine, the main drain is almost certainly clear.
When should I stop DIY and call a plumber?
If the sink fills rapidly, leaks appear, or plunging makes things worse. That suggests a deeper pipe issue.