Water supply is a natural monopoly which is pretty different straight away. The externalities are really nasty (say you extract water under your property, the water doesn't care about property lines so water will flow from other land and potentially cause subsidence, a big cost to somebody else) and water is actually part of a global cycle so while one person can get away with just taking their water from a well and dumping effluent into the lake if a million people do that a bunch of them are going to die.

And as a result of all this it's heavily regulated unlike printer ink.