How to unblock a toilet: a plumber's step-by-step guide
How to unblock a toilet safely with a plunger, what not to pour down it, and the signs that the blockage is in the soil pipe or drain instead.
The quickest way to unblock a toilet is with a proper flange plunger and a bit of patience: a firm seal, ten to fifteen steady pumps, then check if the water drains. Most toilet blockages are close to the pan and clear this way. If it does not clear, or other drains in the house are backing up too, the problem is further down the pipe and needs a different approach.
Before anything else, stop flushing. If the pan is already full, another flush can send dirty water over the rim.
What you need
- A flange plunger. This is the type with an extra rubber sleeve that folds out of the bottom of the cup. It fits into the outlet of the pan and makes a much better seal than a flat sink plunger.
- Rubber gloves, and old towels or newspaper around the base of the toilet.
- A bucket and an old jug or cup, in case you need to bail out some water.
How to unblock a toilet with a plunger
- Protect the floor. Lay towels around the toilet and put on gloves.
- Get the water level right. You want enough water in the pan to cover the cup of the plunger, roughly half full. If it is close to the rim, bail some out into the bucket. If it is nearly empty, add some water from a jug.
- Seat the plunger. Put the plunger in at an angle so the cup fills with water rather than air, then fold out the flange and push it into the outlet at the bottom of the pan.
- Plunge steadily. Start with a gentle push to get the air out, then pump firmly in and out, keeping the seal, about ten to fifteen times. The pull stroke does as much work as the push.
- Lift and look. Pull the plunger away. If the water rushes out, the blockage has moved.
- Test it. Pour in a bucket of water from waist height. If that drains away normally, flush once and watch the level. If it clears, you are done.
- Repeat if needed. Stubborn blockages can take a few rounds. Give it several goes before trying something else.
Once it clears, rinse the plunger in the flushed toilet and wash your hands well.
If the plunger does not work
A toilet auger (sometimes called a closet auger) is a short, cranked drain snake designed for toilets, with a sleeve that protects the porcelain. Feed it into the outlet and turn the handle to break up or hook out whatever is caught. They are not expensive and worth having if your toilet blocks often.
Hot water and washing-up liquid can help with a soft blockage: squeeze in a good amount of liquid, then pour in a bucket of hot, not boiling, water from a height and leave it for 20 minutes. Boiling water can crack the pan.
What not to use
- Chemical drain cleaners. Most are not designed for toilets, can damage seals and pipes, and leave a caustic pool in the pan if they do not clear it. That makes it dangerous for you, and for any plumber who has to deal with it afterwards. If you have already used one, tell us when you call.
- Wire coat hangers. They scratch the glaze and rarely reach the blockage.
- Sink plungers. A flat cup cannot seal in a toilet outlet, so most of the force is wasted.
- Repeated flushing. It only adds water to a pipe that has nowhere to go.
Is it the toilet, the soil pipe or the drain?
Where the blockage sits changes what is needed. These clues help:
| What you see | Where the blockage probably is |
|---|---|
| Only the toilet is slow or blocked | In the pan or the first part of the pipe |
| Toilet and bath or shower drain slowly, or gurgle when you flush | The soil stack or the pipe below where they join |
| Water rises in a downstairs toilet or shower when someone upstairs flushes | Lower down the soil pipe or underground drain |
| Outside manhole or gully is full or overflowing | The underground drain |
If the problem is in the soil stack or underground drain, plunging the toilet will not reach it and may just push water back up elsewhere. Check your outside manhole cover if you can lift it safely: if it is full of water, the blockage is beyond it. In many homes, responsibility for shared drains and sewers beyond your property boundary sits with the water company, so it is worth checking with them before booking anyone for that part.
What usually causes toilet blockages
The same things come up again and again:
- Wet wipes, including ones labelled “flushable”
- Too much toilet paper at once
- Cotton buds, sanitary products and nappies
- Kitchen roll and tissues, which do not break down like toilet paper
- Children’s toys
- Limescale build-up inside the pan outlet over many years, which narrows it
A good rule is to flush only the three Ps: pee, poo and paper.
Macerator toilets are different
If your toilet has a box behind it with a motor (common in loft and basement bathrooms), it is a macerator. Do not plunge it or use chemicals. Switch it off at the spur, and call us. Macerators need specific care, and the wrong approach can damage the pump.
When to call an engineer
- Several rounds of plunging and an auger have not cleared it
- More than one drain in the house is blocked or gurgling
- Dirty water is coming up in a bath, shower or downstairs toilet
- The pan is cracked, or water is leaking at the base
- It is a macerator, or a toilet that blocks again and again
We clear blocked toilets across South and South West London and north Surrey, from flats in Battersea and Clapham to family homes in Wimbledon. Labour is £120 an hour including VAT on weekdays from 8am to 5pm, and £180 an hour including VAT at other times. Full details are on our prices page, and our emergency plumber line runs 24/7, 365 days a year.
If your toilet keeps running rather than blocking, read our guide to a toilet that keeps running. For anything else, call Lee on 020 8050 5913. If he can talk you through it, there is no charge.
Stuck? Call Lee.
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