The market for bottled water is very competitive

A. The market for bottled water is very competitive. However, the water that comes in a pipe to your home (water which may be better than the bottled water) is usually supplied by a government-owned utility. Why are there two different market structures for products that are nearly perfect substitutes?

B. Market economics says that the price of a product should equal its marginal cost. Is that realistic for a public water utility? Why or why not?