How to Clear a Blocked Bathroom Drain (Safely)
Blocked bathroom drains don’t usually happen all at once.
They build up slowly — hair, soap, toothpaste, shampoo and skin oils collect inside the waste pipe until the water starts draining slower and slower.
Before it turns into an overflow, leak, or a back-up into the bath or shower tray, here are safe steps you can try — and how to know when it’s time to stop and call a professional.
Step 1 — Hot Water Flush
- Remove as much water as you can from the basin or bath
- Then suck through the trap (the U-bend under the sink) if possible
This alone sometimes clears the build-up around the trap.
Once the water is removed:
- Boil the kettle and let the water cool slightly (hot, but not boiling)
- Pour it slowly down the plughole
This helps soften:
- Soap and shampoo residue
- Conditioner build-up
- Oils that have cooled and stuck to the pipe
This won’t fix a deep blockage, but it can help movement.
If you have a small wet vac / wet pick-up, that can also help remove loosened waste near the surface.
Step 2 - Remove the Hair Trap / Pop-up Plug
Most bathroom basins and baths have a hair trap built into the plug.
Lift it and clean it.
If it doesn’t lift:
- Twist gently counter-clockwise
- Or check under the basin for a small release screw
This is very often the cause.
Step 3 — Use a Plunger (The Right Way)
Block the overflow hole (the small slot under the taps) with a wet cloth — this increases pressure.
Give slow, firm plunges — not fast aggressive pumping.
If the water level rises and falls, the blockage is moving.
Step 4 — Use a Biological Drain Cleaner (Not Chemical)
Avoid harsh chemical drain cleaners — they can:
- Damage pipe joints and seals
- Cause burns
- Make future repairs more difficult
Use a bio-enzyme cleaner instead. Ensure you always follow the instructions on the product and wear the appropriate PPE.
Let it sit overnight, then flush with hot water again.
When to Stop
Stop immediately and call a professional if you notice:
- The bath fills when the basin drains
- Gurgling sounds from the toilet when the sink empties
- The blockage keeps returning
- Sewer smells coming from the plughole
These signs mean the blockage is not in the bathroom — it’s further down the main line.
At this stage, DIY methods will not solve it.
You risk leakage, flooding, and damage.
What We Do at ASL
Our drainage engineers:
- Fully employed (no commission rushed jobs)
- Trained to diagnose, not just clear
- Carry CCTV cameras on every van
- Clear the pipe and find the cause
This prevents the same problem coming back.
Need Help?
If your drain isn’t clearing:
We’ll clear the blockage properly, check the system, and help protect your home.
