Before you start
Never mix drain products, or pour bleach after a drain cleaner: some combinations give off toxic gas. If a chemical is already sitting in the pipe, don't plunge it, because it can splash onto your skin and into your eyes, and tell the plumber what you used. Wear rubber gloves for all of this.
First, work out what's blocked
Is it one fixture or several? A single slow basin or shower usually means a blockage close by: hair, soap or food in the trap or the first stretch of pipe. That's the kind you can often clear yourself.
If the toilet, shower and basin are all slow, or the shower fills when someone flushes, the blockage is further down, in the line that takes everything to the sewer. A plunger won't reach it, and running more water only pushes the overflow somewhere you don't want it.
Clearing one blocked sink, basin or shower
Clear what you can see
Take out the plug or lift the shower grate. Pull out hair and gunk with a gloved hand or a bent piece of wire. Often that's the whole blockage.
Seal the overflow
Basins and baths have an overflow hole near the top. Hold a wet cloth over it so the plunger's pressure goes down the pipe, not out the hole. On a double kitchen sink, plug the other side.
Use a plunger properly
Leave enough water in the sink to cover the cup. Press down to push the air out, then pump firmly, up and down, for about half a minute without breaking the seal. Lift it off and see whether the water drains. Repeat a few times if it's moving.
Flush with hot tap water
Once it drains, run hot water from the tap for a minute or two to carry the loosened gunk away. Don't use a kettle of boiling water: it can soften plastic pipes and crack a toilet bowl.
Toilets: the right plunger, and no more flushing
Use a toilet plunger, the kind with a flange that fits the bowl. Don't keep flushing a blocked toilet to test it, because it can overflow. If a few goes with the plunger don't clear it, call a plumber.
Stop and call a drain specialist if
- More than one fixture is slow or blocked at the same time.
- Water comes up in the shower, a floor waste or the gully outside when you use something else.
- The overflow relief gully outside is overflowing.
- Other fixtures gurgle while the blocked one drains.
- The plunger hasn't shifted it after a few honest tries.
- You've already used a chemical and it hasn't worked.
- It's the same drain blocking again and again.
What the law lets you do yourself
Plunging is the safe line. In Western Australia, the homeowner list from Building and Energy includes "clearing a blocked fixture or waste pipe by using a plunger", and other drainage plumbing has to be done by a licensed plumber or permit holder. The QBCC's DIY guide in Queensland covers cleaning ground-level grates over a trap. We haven't confirmed lists for other states, so check our guide to what you can do yourself before you take anything apart.
What a drain specialist will do
A plumber will find where the blockage is, often by opening the inspection opening outside, then clear it with a drain machine or a high-pressure water jet (hydro jetting). If it keeps coming back, they may run a camera through the pipe (CCTV drain inspection) to look for tree roots, a crack or a sagging section.
Sometimes the blockage isn't in your pipe at all but in the water company's. Then the plumber should report it straight away. Sydney Water takes claims only where the plumber "reported it to us", and only for "a maximum of 2 hours work". South East Water won't reimburse a blockage the plumber didn't refer to it, and City of Gold Coast caps refunds at "$300 including GST". Our guide to who owns the sewer pipe has each company's rule.
Keep it from happening again
- Wipe greasy pans with paper towel and bin it, rather than washing fat down the sink.
- Fit a hair catcher over the shower and bath outlets.
- Flush only toilet paper. Wipes, even ones sold as flushable, belong in the bin.
- Keep the gully grate outside clear of leaves, soil and mulch.
What we would do
Give the plunger a fair go on a single slow fixture, and leave the chemicals on the shelf: they rarely reach a deep blockage, and they make the job riskier for whoever comes next. If two fixtures play up at once, put the plunger away and call. That blockage is in the main line, and the sooner a drain specialist clears it, the less chance it overflows inside.