The third international conference on sustainability engineering and science kicks off at the University of Auckland today, and central to discussions is the issue of water purity.
Dr Carol Boyle is the chair of the conference and she says that flushing expensive clean water down the toilet is hugely wasteful.
Visiting water expert Jean Venables agrees and Zimbabwe's cholera outbreak is an example of what can occur when the clean water supply is jeopardised.
They both spoke to Sunrise.