Some stats & facts
Average american family 400 gallons of water a day
Dialysis uses tremendous amounts of water — 32 gallons (120L) required during a typical dialysis session. Water purified by reverse osmosis prior to entering dialysis machines & water rejected by reverse osmosis goes down the drain.
7.13 billions gallons of potable grade A water wasted per year, with high salt content being its only problem. After desalination, it meets standards set by WHO & united nations food and agriculture organization for use in irrigation & landscape.
All the water, if saved and used, is enough to supply a city as big as salt lake city
It has already been done in Australia. more details in this link
Some more facts from the Australian Pilot Project
The RO water, better than drinking water wasted at 1100ml/min. It also fell within all national and international requirements for drinking water.
This otherwise rejected water was stored in tanks. They supplied the central sterilization department, the rest was used for cleaning, gardening, laundry and toilets.
The australian practice also adapted solar power that powered the reverse osmosis machines and also the dialysis machines. The cost of setting all this up turns out to be lesser than conventional expenses (electricity and waterbills) in the long run. It even becomes an income generator, once the cost is paid back.