Given the low cost of household water use, people will not take serious conservation measures unless they are hit in the wallet.
From America’s Environmental Report Card: Are we making the grade? by Harvey Blatt:
In Brazil, they have implemented digital water. A device known as a water manager allows people to pay as they go. Users buy a pre-paid card, like for cell minutes, programmed for a number of credits. At home, you load the card and then the water company supplies you with that many credits of water. “Households using the water manager saved 40 percent on their water bills. Becoming increasingly conscious of what something costs gets people to use less.”