eli5 Is there a reason the waste water like from showers can’t be filtered through pipes and used for toilet water?

Question

eli5 Is there a reason the waste water like from showers can’t be filtered through pipes and used for toilet water?

In: 797

Answer 1

Certain LEED certified level buildings do this. There’s no reason you can’t, it just costs more money and requires storage tanks to hold the grey water used to flush the toilets and the like.

It would be simple enough with new construction, but for older houses it would require a complete replumbing of the entire house.

Furthermore, most bathrooms contain the shower and the toilet and the toilet is always higher than the drain of the shower. So you need some way to pressurize that drain water to lift it high enough to be used in the toilet, which requires pumps or other devices.