A blocked bathroom basin is one of the most common household plumbing headaches, and in most cases you can clear it yourself using a basic cup plunger — no chemicals, no special skills required. Here's how to do it properly so you get results first time.
What You'll Need
Before you start, gather these items:
- A cup plunger (the flat-bottomed rubber type — not a flange plunger, which is designed for toilets)
- Old towels or rags
- A pair of rubber gloves
- A small bucket
- Petroleum jelly (optional, but helps create a better seal)
You'll find cup plungers at Bunnings or Mitre 10 for a modest cost — as a rough guide, expect to pay somewhere in the range of $10–$30 depending on quality.
Step 1 — Remove the Pop-Up Plug or Drain Cover
Most bathroom basins have either a pop-up waste plug (operated by a rod behind the tap) or a simple removable drain cover. Take this out so you have clear access to the drain opening. Give it a rinse — hair and soap scum often build up on the plug itself and removing it alone can improve drainage.
Step 2 — Block the Overflow Hole
This is the step most people skip, and it's why their plunging doesn't work. Your basin has a small overflow hole near the top of the bowl (usually at the front, just below the rim). If you don't seal this, the air pressure you create with the plunger will simply escape through the overflow rather than pushing down into the blockage.
Fold a damp cloth or rag and press it firmly over the overflow hole. Hold it in place with one hand while you plunge with the other, or ask someone to hold it for you.
Step 3 — Add Water to the Basin
Pour enough water into the basin to cover the rubber cup of the plunger by at least 2–3 cm. This water is what transmits the pressure — plunging a dry drain is much less effective.
Step 4 — Create a Good Seal and Plunge
Place the cup of the plunger directly over the drain opening. If you like, smear a little petroleum jelly around the rim of the rubber cup to improve the seal against the basin surface.
With the overflow hole blocked and the plunger seated firmly:
- Push down slowly and steadily to compress the cup.
- Pull back up sharply — this is the stroke that dislodges the blockage.
- Repeat 10–15 times in a rhythmic pumping action.
- On the final stroke, pull the plunger away quickly to release suction.
Check whether the water drains freely. If not, repeat the process two or three more times.
Step 5 — Flush the Drain
Once the water starts draining, run the hot tap for a minute or two to flush any remaining debris further down the pipe. This also helps clear away soap scum that may have contributed to the blockage.
Common Causes of Bathroom Basin Blockages
Understanding what caused the blockage helps prevent the next one:
| Cause | Prevention |
|---|---|
| Hair build-up | Fit a drain strainer/hair catcher |
| Soap scum accumulation | Flush with hot water weekly |
| Toothpaste and product residue | Rinse basin thoroughly after use |
| Pop-up waste plug clogged | Clean the plug monthly |
A Note on Chemical Drain Cleaners
It's tempting to reach for a bottle of chemical drain cleaner, but use these with caution. Many caustic products can damage older pipes (especially chrome or PVC fittings), are harmful to the environment, and can cause serious skin and eye burns. WorkSafe NZ recommends always reading product labels and wearing appropriate PPE if you do use them. Mechanical methods like plunging are generally safer and just as effective for hair-and-soap blockages.
When to Call a Professional
Plunging works well for minor blockages close to the drain opening, but there are times when you should call a qualified drain cleaner or plumber:
- The basin is still blocked after several attempts with the plunger.
- Multiple fixtures in your home are draining slowly at the same time — this suggests a blockage further down the main drain line.
- You notice gurgling sounds from other drains or the toilet when you use the basin.
- There is an unpleasant sewage smell coming from the drain.
- Water is backing up into other fixtures.
- You suspect a collapsed or damaged pipe (common in older NZ homes with clay or cast-iron drainage).
Drain cleaning and drain repairs that involve work on the drainage system beyond the fixture trap may constitute restricted drainlaying work under the Plumbers, Gasfitters, and Drainlayers Act 2006. Always use a licensed professional for anything beyond basic unblocking. You can check licensing requirements with the Plumbers Gasfitters & Drainlayers Board.
For peace of mind, find a qualified local drain cleaner or plumber on tradedirectory.co.nz.
Master Plumbers
Certifying Plumber
SiteWise
