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

The city of Hong Kong does a lot of grey water use. There are a lot of people there and anything that can be done to reduce drinking water usage is very important.