This is not an unusual problem, but the dimensions of Cornwall's situation (45/48-percent loss rate) seem to be well outside the usual parameters. I coincidentally happen to be reading the excellent book "The Big Thirst: the Secret Life and Turbulent Future of Water," by Charles Fishman, and here's a paragraph from it:

"One of the largest daily consumers of water isn't a use of it at all. One of every six gallons of water pumped into water mains by U. S.utilities simply leaks away, back into the ground. Sixteen percent of the water disappears from the pipes before it ever makes it to a home or business or factory. Every six days, U. S. water utilities lose an entire day's water. And that 16-percent U. S. loss rate isn't too bad--British utilities lose 19 percent of the water they pump; the French lose 26 percent."

I'm guessing we have water mains made from old logs and crap concrete.

I fear this audit will find that miles of our pipes should be replaced. About 20 years ago, with small children in the house, we had our water on Deer Hill Road repeatedly tested. As we suspected the water was mildly contaminated. We petitioned the Village to fix the situation. The water pipes were 100 years old and, to our knowledge, had never been serviced. The Village agreed to clean the pipes by internally scrubbing them. It found that the pipes had a huge internal layer of black crud that had significantly narrowed their water-carrying radius. I well remember a driver stopping to look at the work going on, sniffing the air,then turning to a companion and saying, "They're cleaning the sewer pipes." We don't have sewer service on Deer Hill. The quality of the water improved and so did the water pressure. But, of course, cleaning the pipes did nothing to stop potential leaks in pipes that are now 20 years older.