Why is the pipe curving under the sink?

Posted in 7 - How things work, Pipelines

The curved pipe under the sink is called a siphon..

Dirt from the water running down the pipe breaks down on the way to the sewer. Decomposed water gives off a foul-smelling gas called sewer gas.. The siphon and the water left in it prevent the gas from spreading through the house.

Sewer gas

has to leave


In some buildings it comes out through a pipe that reaches the roof.

Sometimes, used water from the sink does not go down the drain. When this happens, means that something is blocking the drain pipe. How to get the water to descend?

The first thing we do is try a rubber ball placed on the end of a stick.. This device is called a suction cup opener..

We place the unobturator in the drain opening. The rubber covers this opening and traps some of the water that cannot come down the drain.

By squeezing the suction cup we push the water towards the drain.

After, we pull the suction cup up. The air that comes from the drain goes to the rubber and absorbs the water it has trapped.

Pull and push. Pull and push.

Moving water shakes everything that blocks the pipe. Suddenly, what the shutter unravels. So, dirty water goes down the drain.

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