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

In Australia many commercial buildings will reuse greywater from sinks and showers for irrigation and toilet flushing.

This involves having separate drainage and reticulation pipework and a rather expensive treatment systems. The water quality is usually quite good after treatment, you can’t drink it of course, but health risks are minimal if the system is correctly designed and maintained.

However these systems usually don’t save money. Water is cheap and energy and equipment (and ongoing maintenance) are expensive.
These systems are usually used to meet stringent ‘sustainability’ certifications like green star that the building owner can then market to prospective tenants or purchasers.