Well water coming from an adjacent property; how to proceed?

[Brad E.]

I'm in due diligence on a house and just learned that this house does not have its own water supply.  The water is sourced from a well on an adjacent property that is owned by a different person.  

This property is on some family land that was divided and sold off to different individuals many years ago.  The original tract had a single well.   That well is now on its own lot and is feeding 3 lots total (including the one I'm buying).

The current owner says it hasn't been a problem (shes been there 15 years) and if she ever needs anything related to water, she just calls the neighbor and he addresses the problem.  There is nothing in writing regarding this agreement. Sounds like that's been working out fine for her but I really cant rely on that.  Not to mention I'm sure it will be difficult for me to sell the property later because of this.

The obvious options are 1) Drill a new well 2) see if its possible to connect to city water.  Both of those sound costly but I have not priced it yet.

I was wondering if anybody has had a situation like this, and how they handled it.  Also, if there are any other options that I am not thinking of. 

Any advice is appreciated.