We have friends and family with this issue.
The issue is "how far is the septic tank drain field from a waterway or pond".
If it is less than a specified distance then when the house is sold the septic system has to be brought up to compliance BEFORE contracts can be exchanged. Who pays is up to the prospective buyer and seller.
The work has to be done by a specialist contractor and the new micro sewage system does need regular servicing.
In our case my SIL is in the last stage of a messy divorce, the house has to be sold and it has an old style system, shared with another house.
The other homeowner is unwilling to be involved, so the house sale and the financial settlement part of the divorce has stalled.
As neither my SIL noreher ex can fund the work it seems to be an impasse.
They have explored getting a court to order the neighbour to pay his share, but the courts will not get involved.
So, SIL continues to live in the home, the EX in rented accomodation and both are VERY unhappy as they cannot move on.
