How to unblock a toilet safely

First, stop the bowl overflowing

The worst thing you can do with a blocked toilet is flush it again to see if it clears. Each flush adds a full cistern of water to a pan that cannot empty, and that is how a blockage turns into a wet floor or a leak through the ceiling below.

If the level is already close to the rim, lift the cistern lid and push the flap or valve at the bottom of the cistern closed with your hand, or lift the float arm so the cistern stops refilling. Most modern toilets also have a small isolation valve on the pipe feeding the cistern, which you can turn a quarter turn with a flat screwdriver. Put old towels around the base of the pan and wear rubber gloves before you start.

If sewage is coming up through a floor drain, a shower tray or an outside gully at the same time, stop using every toilet and tap in the property. The blockage is further down the drain and more water will only push waste out at the lowest point.

Work out whether it is the toilet or the drain

A quick check tells you whether a DIY fix is likely to work. Run a basin tap and the shower for a minute, and look at what the toilet does. Then, if you have an inspection chamber (a manhole cover) outside, lift it and see whether it is full of standing water or waste.

If only the toilet is affected and the water drains away slowly over a few minutes, the blockage is almost certainly in the pan or the first bend of the soil pipe. That is within reach of a plunger or an auger. If other fittings gurgle, drain slowly or back up, or the chamber outside is full, the problem is in the shared drain. Our guide on why drains keep blocking explains the usual causes further down the line.

How to use a plunger on a toilet

A sink plunger with a flat cup is the wrong tool for a toilet. You want a toilet plunger with a flange (a soft extension below the cup) that fits into the outlet at the bottom of the pan and forms a seal. Without a seal you are only splashing water around.

It usually takes several rounds. If the level drops suddenly with a gurgle, that is a good sign. Pour in a bucket of water to test before you try the flush, rather than risking a full cistern.

• Make sure there is enough water in the bowl to cover the plunger cup. Add some from a bucket if the level has dropped.
• Put the plunger in at an angle so the cup fills with water rather than air, then fit the flange into the outlet.
• Press down gently for the first push, then push and pull firmly 10 to 15 times, keeping the cup sealed.
• Lift the plunger away and see whether the water drains. Repeat two or three times if it is moving.
• Once it clears, pour in a bucket of water to check it flows, then flush once and watch the level.

Warm water and washing-up liquid

For a blockage made of toilet paper or waste, rather than a solid object, warm water helps. Squeeze a generous amount of washing-up liquid into the bowl, then pour in a bucket of hot tap water from about waist height. The weight of the water adds pressure and the detergent helps things slide. Leave it for 20 to 30 minutes, then try the plunger again.

Use hot tap water, not a kettle of boiling water. Boiling water poured straight into a cold ceramic pan can crack it, and it can soften the seals on plastic pan connectors. It also does little to a blockage caused by wipes, which do not break down in water at any temperature.

Using a toilet auger

A toilet auger (sometimes called a closet auger) is a short, flexible cable in a rigid tube with a rubber sleeve at the bend. It is designed to go round the trap of a toilet without scratching the glaze, and is sold by most DIY shops. It is the right tool when the plunger has not worked or you think something like a wipe, a nappy or a toy is lodged in the trap.

Put the curved end into the outlet, feed the cable in by turning the handle, and when you feel resistance, keep turning to either hook the blockage or break it up. Pull the cable back slowly. If you have hooked an object, take it out with gloved hands rather than pushing it on into the drain.

A straightened wire coat hanger is often suggested, but it scratches the pan, rarely gets round the trap and can push a solid object further in, where it is much harder to remove. If you know a solid item has gone down the toilet, stop and get it removed rather than forcing it on.

Chemical drain cleaners: use with care

Shop-bought drain unblockers can clear soft organic blockages, but they do little to wipes, sanitary products or objects, and they are hazardous to handle. Never mix two products or add one after another has failed, as some combinations give off harmful fumes. If you have used a chemical and it has not worked, tell whoever comes to clear the toilet so they can protect their hands and eyes.

Macerator toilets, which pump waste through a small pipe, need different care. Do not plunge or use chemicals on them without checking the manufacturer's instructions. Our guide to macerator repair planning covers what usually goes wrong with them.

Stopping the toilet blocking again

Most toilet blockages come from things that should never have been flushed. Wet wipes, even those labelled flushable, do not break down like toilet paper. Cotton buds, sanitary products, nappies, kitchen roll, dental floss and cooking fat all build up in the trap and the drain beyond it. Thames Water's guidance is simple: only pee, poo and paper should go down the toilet.

If the same toilet blocks every few weeks even with sensible use, there is usually a physical reason: a poor fall on the soil pipe, a displaced joint, a pan connector that has slipped, or a partial blockage further down. A camera survey can show which, and saves repeated call-outs for the same fault.

When to call a plumber

Call a professional if the toilet is still blocked after plunging and an auger, if a solid object is stuck, if more than one fitting is affected, if sewage is backing up anywhere in the property, or if the pan is loose or leaking at the base. If you live in a flat and water is escaping towards a neighbour's ceiling, treat it as urgent.

Loyal Plumbers clears blocked toilets and drains 24 hours a day across London and everywhere inside the M25, with 10 vans on the road. Our call-out is £60. It helps to tell us what has already been tried, whether any chemical has gone into the pan, and whether other sinks or the outside drain are affected, so the engineer arrives with the right equipment.