Most water in a residential house is used via the toilets so no treatment needed, wife is in the final process of getting new largish town house built I am trying to figure out a way to have rain water by gravity feed just the toilets with an automatic way the toilets would go over to metered city water when the rain water runs out.
Agreed seems strange so much rainwater is not collected , think if Melbourne had a city plan with residents able to collect their roof rain water from houses send to central rain water storage areas paid by water credits , and then pumped and redistributed back into pipes just for toilet water , wouild probably mean no need for desalination /extra dams etc .
