Question: How does water come out of our taps through our body, down the toilet and back to our taps?

Emily Hayward answered on 16 Jun 2014:

Thats a very good question!

The water systems are all very complicated. Pure water only contains water molecules containing water and oxygen, but usually there are other things in it too. The water that comes out of our taps has some minerals and things like that in it (which are caused by rocks weathering in the local area so places like Bath which are sandstone contain more than places like Aberdeen which is all granite….water with lots of minerals is called hard water).

When we drink water our body decides what it needs to do with it, and uses going to the toilet as a way to get rid of waste, so when water passes through us other molecules which our body doesnt want get added to it e.g. urea. We also sweat some water which contains things like salt too.

the water which ends up down the toilet has urea and other waste products from our body in it (carbohydrates, salts, some fats etc) and this, along with anything else which goes down our drains goes to a sewage treatment plant. Here the things like waste products which have been added to the water are removed meaning only water and minerals, and things which wont harm us return to our taps again, and the waste products can go to landfill or somewhere similar. The waste can be removed in lots of different ways, it can be filteres off, chlorine can be usedto break it down to molecules which are released as gas, and bugs can be used to eat the waste to make energy for themselves.