[USS Alaska]

I actually have concerns about squatters rights for a piece of property that I may ineherit atleast 50% of sometime in the future. A neighbor to that property has been aloud to run a drain pipe onto our property for many years without being legally properly challenged for it. So it is an issue in the back of my mind.

Why not start by asking the person that now owns the place if they gave permission to the neighbor for the drainage?

It's always better to start knowing the facts, and your own statement indicates that permission has been given; i.e. aloud = allowed, and allowed = permission, either verbal, written or consent over time by lack of any contrary action.

[Sacajaweau]

Agree with you absolutely. If he granted permission, there is no Adverse Possession. For all you know...the tur owner might want the extra water.