Guide · Drains and toilets
How to unblock a sink
Start with the simplest method and move to the next only if it does not work: hot water, then a plunger, then taking off the trap, and finally a drain snake in the pipe. In most cases the blockage is in the trap, the curved pipe under the sink, and you can clear it with a bucket and a pair of gloves. If dirty water also comes up from other drains, stop: the blockage is further away.
30 minutes Difficulty: EasyUpdated 25 October 2026
If you have already poured in a chemical drain cleaner and the water is standing in the sink, do not use the plunger and do not take off the trap with bare hands: that water is corrosive and can splash. Put on gloves and goggles, open the window and do not add any other product. If you call a technician, tell them straight away what you poured in.
What you need
- Bucket or basin
- Rubber gloves
- Sink plunger
- Wet cloth
- Old toothbrush
- Manual drain snake
- Adjustable pliers, only if the nuts are stiff
Step by step
Tap a step to mark it as done.
Kitchen sink: grease and the dishwasher
In the kitchen the blockage forms from grease, which cools in the pipe and traps crumbs, rice and coffee grounds. So it is often not only in the trap: it settles along the pipe that runs through the wall or behind the cabinets. If the water drains well for a few days after you clean the trap and then blocks again, the deposit is further along and you need the snake.
If the dishwasher drains into the sink trap, a blocked drain means dirty water comes back up into the basin on every wash. Before taking everything apart, look at the dishwasher's grey hose. It must not be squashed or kinked behind the cabinet, and the connection on the trap must be clean.
To avoid starting over, let frying oil cool and pour it into a bottle for the used-oil collection. On very greasy dishes, wiping with kitchen paper before washing removes most of the grease that would end up in the pipe.
Bathroom sink: hair and the overflow
In the bathroom the blockage is almost always a clump of hair, toothpaste and soap just under the hole, wrapped around the stopper. On some sinks the stopper lifts out when you pull it up or turn it. On others you free it from underneath by unscrewing the small nut on the rod connected to the lever.
The overflow hole at the top of the basin collects soap splashes that nobody rinses. When it is dirty it also smells. Clean it with a bottle brush and a little hot water with washing-up liquid.
Unblocking a sink naturally: what really works
The most effective natural remedy is a tool: a plunger, a trap taken apart and a snake clear the blockage without putting chemicals in the pipe. Hot water and washing-up liquid help with light grease and keep the drain clean, but they do little against a real blockage.
Baking soda and vinegar foam a lot, but the two cancel each other out and do not dissolve a plug of hair or grease. Baking soda and coarse salt can help with a mild slowdown. It is better to keep them for maintenance.
Caustic soda dissolves grease, but it is corrosive to skin, eyes and metals, and muriatic acid can damage plastic and ceramic pipes. If you decide to use a drain cleaner, do it only when the water has drained, with gloves and goggles. Follow the label and never mix it with other products, such as bleach.
When to stop and call a technician
- Dirty water also comes up from the shower, the bidet or another sink: the blockage is in the branch pipe or in the building's main stack
- The trap is clean and the snake does not go past the first stretch of pipe
- The nuts are seized, or the trap is so old that it cracks as soon as you touch it
- The kitchen sink blocks again after a few days
- You have already poured in a chemical drain cleaner and the water is standing in the basin
Frequently asked questions
How do I unblock a kitchen sink naturally?
Start with very hot tap water and a little washing-up liquid, then move to the plunger with the other basin plugged. If that is not enough, take off the trap and clean it. Vinegar and baking soda together cancel each other out and do little against a real blockage.
How do I unblock a badly clogged sink?
Take off the trap and push a spring snake straight into the wall pipe, rotating it as you push. If the snake will not pass, or if water comes back up from other drains, the blockage is far away and you need a professional machine.
Can I pour boiling water down the sink?
Very hot water from the tap is better. A pan of boiling water now and then usually does not ruin the pipes, but old plastic fittings and quartz or granite sinks do not like sudden temperature changes.
Does caustic soda work in a sink?
It dissolves grease, but it is corrosive, and in a sink full of water it just dilutes without reaching the blockage. It also makes it dangerous to take off the trap afterwards. Try the mechanical methods first.
How much does it cost to have a sink unblocked?
On quote websites in the Naples area, the usual range is roughly 70 to 250 €, depending on how far away the blockage is. We cover Campania. If you want to try yourself, we can guide you through taking off the trap on a video call.
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