Just thinking (dangerous I know...)
Right - when "we" use R/O's 2/3 of the water goes straight to the drain. When we wfp a lot of the water we use goes into the custies drains and thus in both scenarios is available for the water companies use inasmuch that it flows to a point where it is pumped back into the system.
When "they" (householders) water the lawn in hot conditions it gets used up by the plants/grass and takes a huge amount of time to get back into the system although it eventually goes into the clouds by evaporation or rivers but may take months.
So a huge proportion of wfp water goes straight back into the drains and isn't lost. Moreover it helps dilute the soap and stuff from car washers and pot washes.
So it's pretty environmentally friendly really.
No comments please from tradders with their filthy soapy water which takes zillions of litres of clean water to cleanse just 5 soapy litres from their buckets before it is usable again. 