I remember that from a hydrology class. Homeowners really liked their well water: said it made great coffee, tasted good, had "body."
Their secret - well downgradient from a cemetery.
I remember touring cemeteries in New Orleans - new bodies were placed in the top half of the above ground crypt. After a few years, the remains - now just bones, are pushed to the back where they fall into the bottom half, thus making room for the next family member.