Blocked Toilet? How to Clear It, and When to Call

Short answer: most blocked toilets clear with a flange plunger and a bit of patience. If that doesn't work, try dishwashing liquid and a bucket of hot (not boiling) water, then a toilet auger. If other fixtures are gurgling or backing up too, or the gully outside is overflowing, the blockage is in the drain, not the toilet. That's when to ring a plumber.

A blocked toilet always seems to happen at the worst time. Here's how to deal with it calmly, in the order a plumber would try things.

First: stop it overflowing

If the water is rising in the bowl, don't flush again. Reach behind the toilet and turn the stop tap clockwise to shut off the water to the cistern. If you can't find it, lift the cistern lid and hold the float up so it stops filling.

Then wait. Often the water level drops slowly on its own, which tells you the blockage is partial and close to the toilet. That's the easiest kind to clear.

Step 1: use the right plunger

There are two kinds of plunger, and only one is right for a toilet.

• A cup plunger is the flat, simple one. It's made for sinks and showers, and it doesn't seal in a toilet bowl.
• A flange plunger has a soft sleeve that folds out from the cup. That sleeve fits into the toilet's outlet and makes a seal.

Use the flange plunger. Make sure there's enough water in the bowl to cover the cup, push down gently the first time to push the air out, then plunge firmly up and down ten or fifteen times without breaking the seal. Pull it away sharply at the end. If the water rushes out, you've cleared it. Flush once to check, with your hand ready on the stop tap.

Step 2: dishwashing liquid and hot water

If plunging doesn't shift it, squeeze a good dash of dishwashing liquid into the bowl. Then pour in a bucket of hot tap water from about waist height and leave it for 15 minutes. The soap helps lubricate the blockage and the weight of the water pushes on it.

Not boiling water. Boiling water can crack a porcelain bowl, and a cracked toilet is a much bigger job than a blocked one.

Step 3: a toilet auger

A toilet auger, or closet auger, is a short drain snake with a bent rubber-sleeved end that protects the bowl. Feed the end into the outlet, turn the handle to work the cable around the bend, and push through or hook the blockage. They're cheap at a hardware store and they reach further than a plunger can.

Don't use a straightened coat hanger. It scratches the porcelain and rarely reaches the blockage.

What not to do

• Don't keep flushing. Each flush adds water with nowhere to go.
• Don't use caustic drain cleaner. It rarely clears a toilet, it's hard on older pipes, and it leaves a burn risk in the bowl for whoever opens the drain next.
• Don't force anything rigid down the toilet. Cracked porcelain or a cracked pipe turns a small job into a replacement.

Signs it's the drain, not the toilet

The toilet is often the first place a drain blockage shows up, because it puts the most water down the line at once. If any of these are happening, the problem is further down:

• The shower, bath or basin gurgles or drains slowly when you flush
• Water comes up in the shower or floor waste when the toilet is flushed
• The overflow relief gully outside (the grate with a loose cap, usually near the bathroom or laundry) is overflowing
• More than one toilet in the house is affected
• The toilet blocks again within days of being cleared

That points to a blockage in the sewer line, and plunging won't reach it. In older Maitland homes it's often tree roots in the original clay pipes, and the heritage streets of East Maitland and Lorn are full of them. Our blocked drains service explains how we clear them and put a camera down the line to see why.

A toilet that keeps running is a different problem

A blocked toilet won't empty. A running toilet won't stop filling: you hear the cistern hiss long after the flush, or see a thin trickle running down the back of the bowl. It doesn't flood anything, so it's easy to ignore, but a cistern that trickles all day can put hundreds of litres a day down the drain and onto your water bill.

The cause is almost always inside the cistern. Lift the lid and look:

• The inlet valve lets water in and should shut off when the float rises. If water is still coming in when the cistern is full, the valve or its washer has worn.
• The flush seal at the bottom of the cistern holds the water in until you press the button. If it's perished or has grit under it, water seeps past into the bowl, and the inlet valve keeps topping it up.

Both are small parts and a short visit. If you're not sure whether the toilet is the only thing using water, turn everything off and watch the meter, the way our water leak detection page explains. A meter that keeps moving with the toilet's stop tap off means the leak is somewhere else.

Why toilets block

Most blockages come down to something that shouldn't have been flushed.

• Wet wipes, including the ones labelled flushable. They don't break down like toilet paper, and they catch on every joint.
• Paper towel and tissues. They're made to stay strong when wet.
• Sanitary products, cotton buds and dental floss.
• Too much paper at once, especially in a low-flow toilet.
• Toys. If there's a toddler in the house, it's worth asking.

The rule is short: only the three Ps go down the toilet. Pee, poo and paper.

When to ring a plumber

Ring if you've tried the plunger and the auger and it's still blocked, if water is coming up somewhere else in the house, if the gully outside is overflowing, or if the toilet keeps blocking. Sewage on the floor is a health risk, so if it's spilling, ring straight away. We treat sewage coming up into the house as an emergency.

The other call that can't wait is a gas smell. That one has its own first five minutes, and our guide to a gas leak at home covers them.

What happens when a plumber comes out

Most blocked toilets we're called to are cleared in under an hour. We start with the toilet itself, then check the overflow relief gully outside and the other fixtures, so we know whether we're dealing with the pan, the branch line from the bathroom, or the main sewer line.

If it's the pan, a professional toilet auger or a short run with an electric eel usually clears it. If it's further down, we open the line at the nearest access point and clear it with the eel or the jetter. Once it's running, we can put a camera down to show you what caused it, which matters most when the toilet has blocked before.

Sometimes the cause is the toilet pan itself. An old pan that's been knocked, or one with a rough or cracked trap, catches paper every time. Replacing it is a bigger job than clearing it, so we show you what we found and price it before anything is done.

When we're finished, you get a short explanation of where the blockage was, why it happened and whether it's likely to happen again. You get the price before we start.