Good advice, thank you. I'll be getting an attorney to cover myself, and I'll certainly make the seller deal with this issue before purchasing.

A few related questions:

1. If she's able to get a prescriptive easement, would that allow her to only use the land for the existing septic leech field, or would it allow my neighbor to put a new one in to replace the existing one when it fails. It was installed in 1971 and has got to be close to the end of it's useful life.

and

2. If after I purchase the parcel, is it legally possible for me to grant her easement for the existing field only and not for any future fields which have to be put in to replace this one when it malfunctions?

and

3. What if she sells her house? Will the next owner retain the easement?

Thank you for any advice you can give,
Matt