Massachusetts famous “Title V” decreed that no septic systems be faulty AND that they release treated water only well above the water table. This allows the ground to “leach out” the impurities before the water reaches the underground water table. In essence the law forced septic systems to go wide and shallow, whereas before they could go deep and narrow – to the detriment of the water table below.
From The Massachusetts Department of Environmental Protection: “Guidance for the Inspection of On-site Sewage Disposal Systems” – A detailed guide to inspecting a septic system. “Location of the bottom of the leaching facility compared to the HIGH ground water elevation is the most common reason for the failure of systems inspected. It is also the most important reason that sewage is not adequately treated before it enters the ground water table.” …. and we complied:
Here's What I Found 