I really do believe the next step in water purification will be
(water from air) machines with built in filters to bring the water down to 000 tds, this type of system would get past the water authority's hose bans ect, these purifying machine may be expensive, but those who purchased them,
could receive a license to prove they produce water this way, and not from the mains tap, here's a company that seems to be ahead in this type of machine technology,
http://www.air2water.net/commercial_applications.htmlthis is the type of machine that is getting close to the technology i am talking about
http://www.air2water.net/commercial_products_aquosus.html