I agree that some municipalities waste water, but I know alot of them do not get it from the ground either. They have to pump it out of rivers and treat it, which adds up. I agree that you should use your spent water to water the lawn, as it takes a tremendous amount of work to condition waste water to be released back into the environment. I think that the energy spent on making ice would be offset if you factor in how many gallons of water you save by recirculating it. I make alot of ice out side this time of year and I could store it for latter in the deep freeze if I wanted but not everyone has the benefit of -20 winters
I get alot of my ice from either liquor stores when I buy something there(free bag with purchase) or the excess capacity of my freezer with 3 ice cube trays. You would be shocked how many gallons of water chilling your wort takes. Also most showers have the water saving heads installed. Just my 2 cents.