Bottled water costs orders of magnitude more than tap water, so there's little danger that raising water rates will provide much incentive to switch to tap water.

I live in Santa Barbara. The first 3000 gallons of tap water I use each month cost 0.5 cents per gallon. Even the most expensive rate for my water is only 2 cents per gallon. Bottled water, even in bulk, tends to cost $0.50 or more a gallon.

And of course agricultural users pay an order of magnitude less than I do.