It Is not quite true to say that water is being "lost" through leaky pipes; it is just returning to where it came from in the first place. The only resources being wasted are fossil fuels used to "circulate" the leaking water (which is not to say that this is not irresponsible). Repairs will reduce apparent consumption but ground water and river levels will continue to fall because actual consumption will stay the same.
One of the worst types of waste are the giant sprinklers we see all over the countryside. Couldn't someone devise a better system of irrigation?
You are right about the opinion of a lot of people though: "I've paid for it, I can use it."