To what extent does regulation lead to equilibrium price and output levels that are consistent with production and allocation efficiencies?

Consider a local public utility, such as the water utility or scavenger company, that is regulated. Provide a diagram or graph illustrating the typical price and output set by regulators. Then respond to the following questions:
What might happen if the company was not regulated?
To what extent does regulation lead to equilibrium price and output levels that are consistent with production and allocation efficiencies?