How to unblock a drain: 6 things to try before calling a plumber

A blocked drain builds up over time. In the kitchen, grease and food scraps set on the inside of the pipe. In the bathroom, hair and soap residue cling to the shower and basin waste. Limescale narrows the pipe over the years, and wipes flushed down the toilet eventually block the shared drain. Outside, tree roots can get into an underground pipe.

The signs: water drains slowly, gurgling, bad smells coming up, then standing water in the sink or shower tray.

Before picking a method, check which outlets are affected. That tells you whether you can clear the drain yourself.

• Just one outlet (sink, basin or shower): the blockage is in the trap or the pipe just after it. The fixes below have a good chance of working.
• Water comes up in the shower when you empty the sink, or several outlets are blocked: the blockage is in the shared drain or the soil stack. Stop using water and call a plumber.
• An outside manhole is overflowing, or water is backing up in the basement: the outside drain is blocked. That's a job for a professional.

First scoop out standing water with a glass. Squeeze a good dose of washing-up liquid into the plughole, follow with a litre of very hot water and leave it a few minutes. Then rinse with the hot tap.

The washing-up liquid breaks down grease and the hot water carries it away. It works on a slow kitchen drain, not on an object.

Careful with boiling water. On plastic (PVC) waste pipes, the grey or white ones, boiling water can warp the pipes and seals. Use very hot, not boiling, water. And never boiling water in a toilet bowl: the ceramic can crack.

Bicarbonate of soda and vinegar fizz together and loosen light build-up. It helps a slow drain or a bad smell, much less a stubborn blockage.

1. Scoop out standing water — So the mixture reaches the blockage.
2. Pour in the bicarbonate — Half a cup of bicarbonate of soda (baking soda) straight into the plughole.
3. Add the vinegar — A cup of white vinegar, then cover the plughole with a cloth: the mixture works inside the pipe.
4. Leave 30 minutes, then flush — With a litre of very hot water. Repeat once if it drains better but not yet normally.

Leave a little water to cover the plunger cup. Block the overflow with a damp cloth, and on a double sink the second bowl too: otherwise the pressure escapes. Pump firmly about ten times, then pull away sharply. Repeat two or three times.

If the water starts going down, run hot water to flush away what's left.

Under a sink or basin, the trap is the U-shaped or pot-shaped part. Put a bucket underneath, undo the nuts by hand, empty and clean the trap, then refit it with its washers. A large share of blockages are right there.

In a shower, it's almost always hair just under the grate. Lift off the grate and the waste cover, pull the hair out with a plastic hook, then flush with hot water.

Trap clean but the water still won't drain? The blockage is further along the pipe. A hand drain snake (or hand auger) is a flexible coiled cable with a handle, sold in DIY shops.

With the trap off, feed the snake into the pipe, pushing gently while turning the handle. When you feel resistance, keep turning to break up or hook the blockage, then pull the cable out and wipe it. Refit the trap and flush with hot water.

A hand snake reaches a few metres. Beyond that, in the soil stack or under the floor slab, you need an electric drain machine.

If a manhole in the garden or yard is full of water, the drain beyond it is blocked. You can lift the cover to see where the water is coming from, but clearing it takes equipment: an electric drain snake, high-pressure water jetting to clean the pipe thoroughly, and a camera to find the cause, such as roots.

Drain-cleaning hoses that fit a pressure washer do exist. Indoors, they can force dirty water out of another outlet. If you use one outside, wear safety glasses and gloves.

Drain cleaners based on caustic soda or hydrochloric acid are dangerous. They burn skin and eyes, can damage pipes and seals, and if they don't get through, they sit in the sink and make the job risky. Never mix two products: some give off toxic fumes.

Enzyme drain cleaners are gentler and good for upkeep, not for a blockage that's already there.

• Pouring one product after another in the hope it clears.
• Poking with a coat hanger or screwdriver: you can pierce the trap or push the blockage further in.
• Keeping the water running while other outlets fill up.

In these cases, see our blocked drain page: electric drain snake, water jetting and a camera if needed, with the price given before we come. Send us a short video of the water draining on WhatsApp, it helps locate the blockage. For a sink or toilet, see our guides blocked sink and blocked toilet too.

• The trap is clean, the drain snake didn't help, and the water still won't drain.
• Several outlets are blocked, or water comes up in the shower, bath or toilet.
• The blockage comes back after a few days or weeks.
• A chemical product has already been poured in and is sitting there.

For every other water problem, see our plumber in Luxembourg page.

• Cooking fat and coffee grounds go in the bin, not down the sink.
• A strainer on the kitchen plughole, hair catchers in the shower and basin.
• No wipes down the toilet, even "flushable" ones.
• Once a month, a litre of very hot water with washing-up liquid down each drain.