I had a home two years or so back that was on a shared well with 2 other homes. This was an issue with VA on this home, I would imagine that it could be an issue with FHA and maybe some lenders as well. It was my understanding that the owners all needed to form a mini-association that would manage the well so that if the pump broke down or some other issue occurred it would be repaired. The VA had a concern that if something happened the home could be without water. From what I was told by the Realtor that it delayed the closing by almost two months.