Clear a Blocked Kitchen Sink by Working Through Fixes in Order

Start here: a blocked kitchen sink, or one that drains slowly. Give yourself about 30 minutes, a bucket, a pair of rubber gloves and a towel.

1. Clear the plughole and run the tap for a few seconds to see how bad it is. One minute.
2. Pour in very hot water from the kettle, or the hottest tap, slowly. Two minutes. If your sink is stainless steel with metal waste pipes, boiling water is fine. For ceramic sinks or plastic waste pipes, use hot water from the tap instead, because boiling water can crack ceramic and soften some plastic.
3. Wait and see if the water clears. Five minutes.
4. If not, use a sink plunger. Make sure the plunger covers the plughole, put enough water in the sink to cover its rim, and plunge firmly in short strokes. Block the overflow with a damp cloth if your sink has one. Three minutes.
5. Still slow? Put the bucket under the U-shaped trap beneath the sink, unscrew the nuts by hand if you can, and empty the trap. Clear out any slime or food. Ten minutes.
6. Refit the trap, hand-tighten the nuts, then run the tap and check for drips. Three minutes.
7. Pour a kettle of hot water down to finish. Two minutes.

For most kitchen sinks, one of these steps does the job. The rest of this article covers why sinks block, the safe way to use a bicarb-and-vinegar fix and the point at which you should stop and call someone.

Why kitchen sinks block

Kitchen drains are usually blocked by a build-up, not a single event. The usual contributors are:

• Fat, oil and grease. They are liquid when hot and set solid in the pipe as they cool, then trap everything else.
• Food scraps. Rice, pasta, coffee grounds and vegetable peel settle and swell.
• Soap residue. It combines with grease to form a sticky layer on the pipe wall.
• Objects. Bottle tops, cutlery and bits of packaging sometimes slip through the plughole.

Over time the pipe narrows, water slows, and a smell often appears before the blockage is complete.

The bicarb and vinegar fix, done properly

This is a mild option that may help with grease and odours, though it won’t shift a solid blockage.

1. Remove standing water from the sink.
2. Pour half a cup of bicarb soda into the drain.
3. Add a cup of white vinegar and cover the plughole with a plug or a cloth.
4. Wait 15 to 20 minutes.
5. Flush with hot water.

If it doesn’t help after one go, move on to the plunger or the trap rather than repeating it five times.

What to avoid

• Chemical drain cleaners. They are harsh, they can damage some pipes and fittings, and they are hazardous if they splash. If you’ve used one and the sink still won’t clear, don’t then plunge or open the trap without gloves and eye protection, since there may still be chemical in the water. Never mix a chemical cleaner with bicarb or vinegar.
• Pouring fat down the sink. Hot water doesn’t prevent it from setting further down the pipe. Let it cool, then tip it into a container and bin it.
• Ignoring a slow drain. A small slowdown is the cheapest time to deal with it.
• Poking with wire or sharp tools. You can scratch or puncture a pipe.

What a home owner may and may not do

Rules on plumbing work are set by each state and territory, and they vary. In general, the licence requirement exists for work on the pipework itself, such as cutting, replacing or altering pipes and fittings, and for anything connected to the sewer or to gas and hot water systems. Simple maintenance like using a plunger, cleaning a trap or fitting a strainer is what most home owners do themselves.

If you rent, check your lease and tell your landlord or property manager about a recurring blockage, since the responsibility for repairs depends on the cause and the lease. To check what is allowed where you live, contact your state or territory plumbing regulator before starting any work beyond the steps above.

When it is time to call a licensed plumber

Stop and get a plumber if:

• water backs up into another fixture, such as the laundry or a floor drain;
• you hear gurgling from several drains at once;
• a smell persists after the trap is clean;
• the sink drains well for a day and then blocks again;
• you can see water leaking from a pipe or joint.

Those signs usually mean the blockage is further down the line, where tree roots, ageing pipes or a collapsed section can be the cause. A licensed plumber has the right tools to find it, such as a drain camera and a machine to clear it, and the licence matters if the work involves the pipes.

Stopping the next blockage

• Scrape plates into the bin before washing up.
• Fit a drain strainer and empty it daily.
• Keep fat out of the sink, and wipe greasy pans with paper first.
• Run hot water for a few seconds after washing up.

For more on why drains clog so quickly in the first place, see this guide to fast-blocking drains, and the home plumbing maintenance article covers the regular checks that keep a household’s pipes in good order. If a dripping tap is the next thing on your list, this quick tap fix is the sort of job that suits a Saturday morning.

Keep it from coming back

Next job: put a strainer in the plughole tonight, and start a small lidded container by the sink for fat and food scraps.

Sources: No third-party figures are used in this article. Plumbing licensing is set by each state and territory regulator, whose current rules apply to your address.