A slow drain is annoying, but it is often something you can fix in ten minutes with items from the kitchen or laundry. This guide covers what to try first, what to avoid, and when to stop and call a plumber.

Work out what is blocked

Start by checking how many drains are affected. If only the kitchen sink is slow, the problem is in that sink or its trap. If the shower, basin and toilet are all slow at the same time, the blockage is likely in the main drain line, and a plunger will not fix it.

Also note when it started. A drain that has slowed down over weeks is usually building up with grease, soap and hair. A drain that stopped suddenly often has an object stuck in it, or a tree root has broken into the pipe.

Try hot water and a plunger first

For a kitchen sink with grease build up, boil the kettle and pour the water down in two or three goes, waiting a minute between each. Do not pour boiling water into a porcelain toilet or into old PVC joints that are already loose. Very hot tap water is the safer option there.

A plunger works best when there is a good seal. Block the overflow hole with a wet cloth, put enough water in the sink to cover the cup, and push and pull with steady strokes for about 20 seconds. If water starts to move, keep going until it drains freely.

Clean the trap

Under most sinks and basins there is a U-shaped bend called the trap. It catches a lot of gunk. Put a bucket underneath, unscrew the two nuts by hand, and let the water and sludge come out. Rinse the trap in the laundry sink, check the washers are in good shape, and screw it back on.

Do not over-tighten plastic fittings. Hand tight plus a small nudge is enough. Run the tap and check for drips.

Skip the harsh chemicals

Caustic drain cleaners are tempting, but they can damage older pipes, harm your skin and eyes, and make life harder for the plumber who has to work on the drain afterwards. If a chemical cleaner does not work, the pipe is now full of dangerous liquid. We would rather you called us before using it.

A cheap hand drain snake from the hardware store is a better choice for hair in a shower drain. Feed it in, twist, and pull out the clump.

Signs it is time to call a plumber

Call a plumber if more than one fixture is slow, if you hear gurgling from other drains, if there is a sewer smell in the yard, or if water is coming up in the shower or floor waste when you flush the toilet. Also call if the blockage comes back within a few days of clearing it. That usually means there is something in the pipe that needs a proper look.

A plumber can use a camera to see inside the pipe, and a high pressure water jet to clear grease and roots. That is a much better result than guessing.

How to stop it happening again

Use a strainer in the kitchen sink and the shower. Wipe greasy pans with paper before washing. Never put wipes, even ones labelled flushable, down the toilet. Run hot water for a minute after washing up. Once or twice a year, pour a kettle of hot water down the kitchen drain as a cheap clean.

If you keep getting blockages in the same spot, ask a plumber to check the fall of the pipe and look for roots or a broken section. A one-off clear is cheaper than repeat call-outs.

What not to do

Most people make a blocked drain worse before they call a plumber. Do not pour boiling water down a plastic pipe, as it can soften joints. Do not mix drain chemicals, because the fumes can be dangerous. Do not push a wire or hose hard into a drain you cannot see, because you can wedge the blockage tighter or damage the pipe.

If a toilet and a shower both back up, or water comes up in a floor drain when you flush, stop. That points to a blockage further along, and no amount of plunging at one fixture will fix it.

A calm order to try things in

Start with the simple thing. Remove any visible hair or debris from the plughole. Use a plunger with a good seal and plenty of water over the plug. Check the trap under the sink, put a bucket under it, and clean it out. If the water still does not move, or comes back within days, it is time for a plumber.

Say what you tried when you ring. It saves time, and it tells the plumber what the blockage is likely to be.

When a blocked drain is a health problem

Sewage coming up in a floor drain, a shower or a toilet is a health hazard. Keep children and pets away, avoid contact with the water and wash well if you touch it. Do not try to clear it yourself. Call a plumber and tell them it is a sewage overflow.

If the overflow reaches outside, tell your water authority if the blockage may be in the main sewer. Photos help with any insurance claim.

Bathroom basin and shower blockages

Hair and soap are the usual cause. Lift the pop-up plug or remove the grate and pull out what you can see. A bent wire or a plastic drain tool with barbs catches hair well. Rinse with hot tap water afterwards. If the shower still pools, the blockage is further down.

Outdoor drains and floor wastes

Leaves, dirt and mulch build up in outdoor grates. Lift the grate, scoop out the debris and flush with a hose. A floor waste that smells may have dried out, so pour a jug of water down it to refill the trap.

Need a plumber?

GSA Plumbing Services works across Geelong and Melbourne, 24 hours a day, 7 days a week. Call 0401 041 103 or send us a message through the contact page and we will talk you through your options.

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Where we work: Geelong, Melbourne CBD, Werribee and the full list of service areas.

Talk to GSA Plumbing Services

We work across Geelong and Melbourne, 24 hours a day, 7 days a week. Call 0401 041 103 or use the contact page. Quotes are free and there is no call-out fee.