Nantucket’s Board of Health regulations can be tricky to navigate but can have some of the biggest impacts on development potential and ownership costs for land owners.
Below are some important new issues to consider; please contact our office for more information or with any questions.


  • As of 3/2017, all existing and new drinking water wells are required to be tested every two years for compliance with Mass Drinking Water Standards.
  • If the well fails and cannot be corrected by a filtration system, then a new well may need to be installed (and old well removed) or if the property is near a Town water source, the lot may be required to connect to Town water.


  • Due to recent Board of Health rules, “bonus bedrooms” are no longer allowed – even with Innovative Alternative (IA) septic systems – in the Watershed Protection Districts (Nantucket Harbor, Hummock Pond, Madaket Harbor) and the Wellhead Protection District. Properties in those areas are limited to Title V’s 1 bedroom per each 10,000 sq ft of lot area.
  • Existing septic systems must be inspected every 5 years.
  • Septic systems must be upgraded to Innovative Alternative (IA) systems in the Watershed Protection Districts and the Wellhead Protection District to reduce the nitrogen leaching out into harbors, ponds and the aquifer (with some exceptions).
    • In the Nantucket Harbor WPD, the IA upgrade requirements applies at 1) the time of a sale of the property, 2) the issuance of a building permit to increase living space, 3) upon replacement/expansion of the system, or 4) if there is a system failure.
    • In the Madaket Harbor WPD, Hummock Pond WPD and the Wellhead PD, the IA upgrade requirements applies if the septic system fails and the bedroom count for the lot exceeds Title V’s rule of 1 bedroom for every 10,000 SF of lot area.
      Beginning in July 1, 2019, the more restrictive Nantucket Harbor WPD rules will apply to the Madaket Harbor WPD.


  • Exceptions vary by factors that are not related to which district the property is in; they vary based on the Town’s plan for sewer expansion.
  • If a lot is in an area that has been approved by Town Meeting for sewer expansion, such as part of northern Monomoy and Shimmo, then septic systems only have to meet conventional standards, not IA upgrades, until they connect to the expanded sewer, which will take years.  A buyer must acknowledge the requirement to connect to sewer later.
  • If a lot is an area that is contemplated for sewer expansion, but expansion has not been approved by Town Meeting yet, such as the Somerset area and Madaket Harbor area, but an IA upgrade is triggered, the lot owner can instead enter into under an Administrative Consent Order (ACO) to escrow money that will be available later to either upgrade the septic system to IA or to connect to sewer, as the case may be in the future.
    • In these areas, the ACO option is also available to avoid some upgrades of systems that need repairs, such as failure of the ground water separation requirement, regardless of whether IA is required.

Please note that this newsletter is informational and not intended to provide legal advice or to create an attorney/client relationship.  Please contact an attorney for legal advice.