Legal Question in Construction Law in California

You can not hook up without the water company approval, nor use a public easement for private purposes.

The term "public easement" is somewhat vague and not used in the statutes or, for that matter, court decisions (except when quoting others). When land or a right-of-way is dedicated to public use by its owner, either intentionally or by oversight or neglect, that is usually referred to as a dedication for public use, or by similar terms. (See Gion v. City of Santa Cruz (1970) 2 Cal.3d 29 for a general discussion).

Anyway, whatever it is, you would need to take a closer look at (a) its intended or permitted uses, and (b) whether such uses can be made by anyone, or only by certain persons. Many dedicated public-access rights-of-way across private lands would be limited to pedestrian access.

If it is an easement, the uses that can be made of it would be even more limited, at least in some cases, and the persons who may make those uses would similarly be limited.

For a general discussion of interest, and perhaps but not necessarily reflecting California's law regarding "public easements" and their use, see the North Carolina case of Beechridge Development Co., LLC v. Dahners (1999) published as 511 S.E.2d 18. The various case reporter books can be found in public law libraries in the county seat of all California counties, sometimes but not always in the courthourse.

Overall, I'd say the water company should be more helpful (like answering this question for you!). I have been counsel for a small rural California water district (near Portola) and I know the problem you're facing.