Why it's worth ditching the harsh chemicals

It is tempting to reach straight for a bottle of caustic drain cleaner when the sink starts to gurgle and drain slowly. But those products come with real drawbacks. Most are based on caustic soda or bleach, which can burn skin and eyes if they splash, and they are particularly unforgiving in older homes where the waste pipes may be metal or have push-fit joints that do not take kindly to aggressive chemicals. If you have already poured one product down and it has not worked, adding another can create a dangerous reaction.

The good news is that most kitchen blockages are made of the same things that went down the plughole in the first place: congealed fat, washing-up liquid residue, coffee grounds, tea leaves and small food particles. None of these need industrial chemicals to shift. A little patience, a kettle and a plunger will usually do the job in under half an hour, and without a nasty smell lingering in the kitchen for days.

Start with boiling water and washing-up liquid

For a sink that is draining slowly rather than completely blocked, this is often all you need. Squirt a generous amount of washing-up liquid down the plughole, then pour in a full kettle of just-boiled water in two or three stages, pausing for a minute between each pour. The soap helps break down the grease while the heat melts it away.

One important caveat: if your sink has plastic waste pipes, which most modern kitchens do, very hot water can soften the joints over time. Use hot water from the tap rather than water straight off the boil, and let it run for a couple of minutes. If the water starts to drain more freely, follow up with a few minutes of hot water to flush everything through properly.

The bicarbonate of soda and vinegar trick

This old favourite is worth trying when the sink smells unpleasant as well as draining sluggishly. Tip about half a mug of bicarbonate of soda down the plughole, followed by a mug of white vinegar. It will fizz enthusiastically, which helps loosen soft gunge clinging to the pipe walls.

Leave it for fifteen minutes, then flush with a kettle of hot water. Be realistic about what it can do: it is excellent for mild grease and odours, but it will not shift a solid plug of fat. If nothing changes after two attempts, move on to the plunger.

Using a plunger the right way

A plunger is the single most effective tool for a fully blocked sink, but only if you use it properly. You want a cup plunger, the dome-shaped one designed for sinks, rather than the flanged version made for toilets.

• Seal the overflow. Most sinks have a small overflow hole near the top. Air escapes through it and robs the plunger of suction, so hold a wet cloth firmly over it, or tape over it.
• Add water. There needs to be enough water in the bowl to cover the rubber cup completely.
• Work the plunger. Give fifteen to twenty firm downward pushes, then pull up sharply on the last one. Keep the cup sealed against the bottom of the sink throughout.
• Mind the second sink. If you have a double sink, plug the other drain or the pressure will simply push water up there instead.

You should hear the water start to move. If it does, run hot water for a minute to clear the loosened debris away.

Cleaning the trap and using a drain snake

If plunging fails, the blockage is probably sitting in the U-bend or trap beneath the sink. This is where most kitchen clogs live, and it is easy to reach. Put a bucket underneath, unscrew the trap by hand or with a cloth for grip, and tip the contents into the bucket. You will often find a grey, fatty sludge that is best dealt with by wiping it into the bin rather than rinsing it back down.

For blockages further along the pipe, a drain snake is the next step. Feed it into the pipe, turning as you push, until you feel resistance, then crank it to hook the debris and pull it back out. A straightened wire coat hanger can work in an emergency, but be gentle: it can scratch plastic pipes and damage the inner surface, which makes future blockages more likely.

Keeping the sink clear from now on

A few small habits will save you from repeating this exercise every few months.

• Bin the fat. Pour cooled cooking oil into a jar or wipe pans with kitchen roll before washing up. Fat is the number one cause of kitchen blockages.
• Use a strainer. A simple mesh basket catches food particles before they disappear down the plughole.
• Flush weekly. Once a week, run a kettle of hot water down the sink for thirty seconds to keep grease moving.
• Run hot water after washing up. A final blast of hot water carries residue through rather than letting it settle.

If the sink keeps blocking despite all of this, if water backs up into other fixtures, or if you notice a persistent drain smell, it is worth calling in a professional. A camera survey can show what is really going on in the pipework, and sometimes a proper jetting is the only sensible answer. But for the everyday kitchen blockage, your kettle, your plunger and a bit of patience will nearly always win.