Kitchen drain or kitchen sink blocked? How to solve it

The kitchen drain has it tougher than any other drain in the house. Grease, starch, soap and fine food waste go through it, often also the water from the dishwasher. That builds up slowly, until one day the water stands still. The good news: a blocked kitchen sink can in many cases be remedied with simple means.

Why does a kitchen drain get blocked?

• Fat and oil. Warm fat is liquid, but cools in the pipe and adheres to the inner wall. That layer gets thicker and thicker and catches everything that passes.
• Food scraps and coffee grounds. Rice, pasta, peelings and coffee grounds clump together, especially combined with grease.
• Soap and starch. Washing-up liquid, soap residue and starch form a sticky, soap-like mass with fat that's hard to rinse away.
• The dishwasher. It usually pumps its water away via the trap or a branch of the kitchen drain. A dirty filter or a kinked drain hose sometimes gives the same symptoms as a blockage.
• Insufficient fall or subsidence. If a horizontal section of pipe is too flat or has subsided, debris accumulates. That's often the reason a blockage keeps coming back.

First check: is the problem only in the kitchen?

Run some water in the washbasin, the shower and flush the toilet. If only the kitchen sink drains slowly, the blockage is almost certainly in the trap or in the kitchen waste pipe itself. You can often solve that yourself.

Are other drains also draining slowly, is the toilet gurgling or is water coming up in a gully? Then the problem is deeper, in the stack or sewer. Continuing yourself makes little sense then. In that case, read when to leave a blockage to a tradesman or, in a flat, the article about a blocked stack.

Unblocking kitchen drain: step-by-step plan

1. Stop using water. Don't turn on the dishwasher and scoop standing water from the sink into a bucket.
2. Try hot water. Pour hot water into the drain in several portions, possibly with some washing-up liquid or soda. Preferably don't use boiling water: most kitchen drains are PVC, and boiling water can eventually deform PVC and glued joints. This only helps with a light grease blockage.
3. Use a plunger. Cover the overflow with a wet cloth, and with a double sink also the second drain. Leave a layer of water in the sink, place the plunger straight on the drain and pump vigorously up and down several times.
4. Clean the trap. Place a bucket under the worktop, unscrew the nuts of the trap by hand and remove the dirt. Check the rubber rings, put everything back hand-tight and run water to see if anything leaks.
5. Work with a hand snake. If the trap is clean but it still won't drain, the blockage is in the pipe behind it. Feed a hand snake into the wall opening while turning. If you feel resistance, turn back and forth without forcing, pull the snake back and flush with hot water.

If the water still drains slowly or not at all after these steps, stop. The blockage is then further down the pipe, where you cannot reach it properly with household tools.

What you'd better not do

• No chemical drain unblocker. Caustic products attack rubbers, sealant and older pipes and often don't dissolve a real blockage. If the product remains in the pipe, it's also dangerous for whoever unscrews the trap afterwards.
• No boiling water on PVC, as explained above.
• Do not poke around with wire or a coat hanger. That will damage the pipe and often only push the blockage further down.
• Don't keep flushing if the water is already high. You'll only increase the risk of water damage.

How to prevent a new blockage

• Let frying and cooking fat solidify and dispose of it with general waste, or hand in large quantities according to your municipality's rules.
• Scrape plates and pans into the bin before they go in the sink.
• Put a strainer in the drain to catch food scraps and coffee grounds.
• After washing up, occasionally rinse with hot water and some washing-up liquid.
• Clean the dishwasher filter regularly.

Do you live in The Hague, Delft or the surrounding area? Then also see drain unblocking in The Hague centre or drain unblocking in Delft. Does the drain smell but does drain? Then read about sewer smell in the house.

What does it cost if we unblock the kitchen drain?

If it doesn't work with the plunger and cleaning the trap, the blockage is usually further along the pipe: in the bend behind the kitchen unit or in the collection pipe under the floor. We can reach that with a hand snake or an electric snake, without anything needing to be opened up. In a flat we also check whether the soil stack you share with the neighbours is clear; otherwise the problem will return within a few weeks.

Grease is almost always the main cause in the kitchen. It hardens in the pipe and catches coffee grounds, rice and food waste. After unblocking we therefore also flush the pipe thoroughly, so that no grease layer remains for things to stick to straight away.

What makes the price higher: a blockage far into the main drain, a drain accessible only via a narrow crawl space, or a subsided pipe that first needs to be inspected with a camera. We always discuss this with you first.