How to Unblock a Kitchen Sink Drain

Why Kitchen Sinks Clog So Easily

Kitchen sinks take more abuse than any other drain in the house. Washing-up water carries grease, cooking oil, bits of pasta, coffee grounds, rice, tea leaves and the odd scrap of onion skin. Most of it washes away happily. Some of it doesn't.

Grease is the main culprit. While it's hot it flows down the pipe like a liquid, but as soon as it cools it sets hard, coating the inside of the waste pipe and the trap. Once that sticky layer is there, food particles catch on it, more grease sticks to them, and a blockage begins to build. That's why a sink rarely blocks overnight — it's usually a slow accumulation over weeks and months, which is why you'll often notice the water draining sluggishly long before it stops altogether.

The good news is that most kitchen sink blockages can be cleared with things you already have at home. Before you reach for a bottle of caustic soda, try these methods in order. They're gentler on your pipes, kinder to your nose, and usually just as effective.

Start With Hot Water and Washing-Up Liquid

This is the simplest fix and it works surprisingly often on a sink that's draining slowly rather than completely blocked.

• Pour a good squirt of washing-up liquid down the plughole.
• Follow it with a full kettle of hot — but not furiously boiling — water. Pour in stages rather than all at once.
• Wait five minutes, then run the hot tap for a couple of minutes to flush everything through.

The washing-up liquid helps break down the grease, and the hot water melts it and carries it away. If your waste pipes are plastic — and most modern ones are — stick to hot water rather than boiling, as very hot water can soften plastic fittings over time. If you've already poured a chemical drain cleaner down there, never follow it with hot water, as the reaction can spit back up the pipe.

The Bicarbonate of Soda and Vinegar Trick

For a drain that's sluggish and a bit whiffy, this old-fashioned combination is worth a go. It fizzes, loosens the gunk and freshens the pipe at the same time.

• Tip half a mug of bicarbonate of soda down the plughole.
• Pour half a mug of white vinegar in after it and put the plug in loosely to keep the fizzing mixture in the pipe.
• Leave it for fifteen to twenty minutes.
• Flush with hot water from the kettle.

It won't dissolve a solid plug of fat, but it does a decent job on light build-up and it costs pennies. If the sink is still draining slowly, move on to the next step.

Using a Plunger Properly

A plunger is the most underrated tool in the kitchen. The trick is to use it before the sink is completely full of standing water.

First, if you have a double sink or a dishwasher connected to the same waste, block the other plughole or the overflow with a wet cloth. Otherwise the pressure you create simply escapes out of the other opening instead of shifting the blockage.

Add enough water to cover the rubber cup, then place the plunger over the plughole and push down firmly to create a seal. Give it a dozen sharp, deliberate plunges — down and up, not just down — then pull away quickly. You should hear the water gurgle and start to drain. Repeat two or three times if needed, then flush with hot water.

When You Need a Drain Snake

If plunging doesn't shift it, the blockage is probably further down, most likely in the trap beneath the sink. A drain snake — a flexible coil of wire with a small hook or auger on the end — is designed for exactly this.

• Remove the plug or the plug-hole strainer first.
• Feed the snake slowly down the plughole, turning it gently as you go.
• When you feel resistance, keep turning — you're either hooking the debris or winding through it.
• Pull it back out slowly and wipe off whatever comes up. Repeat until the water runs freely.

If you're handy, you can also place a bucket under the sink, unscrew the plastic trap by hand and clean it out directly. It's usually a five-minute job, and it's where the majority of kitchen blockages actually live. Just make sure the plug is out and the sink is empty before you undo anything.

Stopping the Next Blockage

Once it's flowing again, a few small habits will save you a repeat visit to the same problem.

• Wipe greasy pans and plates with kitchen roll before washing up, and bin the paper rather than rinsing it away.
• Never pour cooking oil or fat down the sink. Let it cool in the pan, then scrape it into the bin or a jar.
• Use a sink strainer to catch food scraps, and empty it into the bin rather than tapping it into the sink.
• Run hot water for thirty seconds after washing up, so anything left in the pipe keeps moving.
• Once a week, flush the drain with a kettle of hot water and a squirt of washing-up liquid.

Chemical drain cleaners have their place, but they're harsh on older pipework, unpleasant to work with and rarely a permanent fix — they clear a channel through the blockage rather than removing it. Try the methods above first. If your sink keeps blocking despite your best efforts, or if water backs up in other parts of the house when you use the kitchen tap, it's worth having a professional take a look, as the problem may be deeper in the system than the trap under your sink.