Why does the toilet "flush" when you pour a bucket of water into it?

Answer 1

Best Answer - Chosen by Asker

If you look at a toilet from the side, you should see an S-shaped curve that leads to the drain. This curve goes from the outlet at the bottom of the bowl, up past the standing level of water in the bowl, and back down to the sewer line.

When the toilet is in "standby" mode with water in the bowl, there is an air pocket in the top part of the "S". Water stays in the bowl since it's not going to overcome gravity to go past the hump in the "S".

When you pour water into the bowl, you are doing the same thing as pulling the lever to flush. Water rushes into the bowl. As the level rises in the bowl, the water level also rises within this "S". At a critical point, the water level rises high enough to go over the hump of the S. One this happens, a siphon is formed. Water is sucked from the bowl all the way down the sewer line as water flows in this siphon.

Once the bowl has emptied, air gets sucked in, which breaks the siphon. As water continues to flow into the bowl (from the bucket or the tank) the air once again blocks the hump in the "S" and the bowl fills.

Asker's Rating:

Asker's Comment:

Cool I always wanted to know that
now I know!
Thanks

Answer 2

The outflow from the pan of the toilet is a U bend. The outoing end of the bend is slightly higher than the access from the pan .This prevents all the 'flush' water from going down the drain - this forms an air tight seal and prevents smell coming back into the toilet/bathroom from the drain.

When a bucket of water is poured into the pan the level of the water in the pan is higher than the 'U' outlet and so runs down the drain until the level of the water is lower than the 'U' outlet when the flow stops and the 'seal' is reformed in the bottom of the 'U'.

Answer 3

Toilets have built-in traps (just like under a sink) that seal out sewer gas when filled with water. the height of the trap determines the depth of water in the bowl. Any "extra" water goes out and into the drain piping. When you pour the bucket of water into the toilet, you have done the same thing as pushing the flush handle. The weight of the water pushes all the contents in the bowl out to the piping and leaves only enough to fill the trap.

Answer 4

No Pain has the most correct answer. If you have ever seen the toilets with the hole down low in the water in the front of the bowl,this is called a siphon jet and it shoots water up the s-trap to start a siphon.Other toilets don't have this jet and once the bowl fills to a certain point it creates the siphon action.

Answer 5

If your toilet has a resivoir for water behind it, it is doing the same thing, instead of opening the valve for the toilet tank, you are pouring the water in the front, which pushes throught the trap, and into the sewer pipe, gravity.

Answer 6

um...i asked a person b4. they said it has something 2 do with the pressure. u r applying pressure by pouring the water in, the toilet balences the pressure out!! well thats all i no

Answer 7

The water pressure causes it to "flush".
But if there is something clogging the commode that method doesn't work; you'd have to use a plunger.

Answer 8

Because it is designed not to overflow