There was another thread about water recently: Anarchism and Water
Someone who purchases a residence and is concerned about water will probably want a guarantee from the water company that water will be provided at a certain price for a certain period of time. Or, the people a neighborhood or town that share the same pipe network could set up a system whereby different water providers input enough water into the pipes to serve the individuals who decide to patronize them (this is even easier with electricity).
The point is that people are going to want some control the price of water before they move in anywhere. A maliciously monopolistic water company will simply drive people out of the neighborhood and cause property values to fall, so the market will favor solutions that prevent this from occurring.