Attendees at the June 16 Board of Health meeting heard several ideas to make accessory dwelling unit (ADU) development easier and less expensive while still meeting Title 5 septic rules.
Rachel Bratt and Janot Mendler de Suarez of the Wayland Housing Partnership and housing advocate Kathleen Boundy asked the board for a clear interpretation of the April 2024 MassDEP ADU guidance memo (see www.tinyurl.com/ADU-title5) and whether homeowners could convert long-unused rooms — like turning a bedroom into a library or office — without increasing the septic system’s design flow when adding an ADU.
Darren MacCaughey, sanitarian and health agent, said local practices permit reconfiguration as long as spaces no longer meet the state’s bedroom definition. Wayland’s current regulations count a room with a closet as a bedroom even if used otherwise but allow the removal of a closet or other structural modifications to downgrade a room. McCaughey emphasized that this case-by-case review is common practice in Wayland and does not require a new policy.
Bratt and Boundy asked for a straightforward way to prove a room has been unused or repurposed. They suggested that documenting long-term non-use could offset the added wastewater flow from a new ADU. For example, empty-nesters could show that a bedroom hasn’t been lived in for years, using voting records, census data, or a temporary occupancy permit to avoid officially raising their system’s design flow.
MacCaughey explained that under Title 5 and Wayland’s local regulations, flow calculations are based strictly on the number of rooms meeting the definition of a bedroom, not on room use or home occupancy. He stated that the local health department cannot regulate based on occupancy levels or private room usage, nor can it rely on self-reported or historical data to override bedroom-based state flow limits.
The housing advocates also recommended adopting alternative wastewater systems like composting toilets and greywater recycling to serve ADUs. Julia Junghanns, Director of Public Health, confirmed that state and local rules already permit general-use and remedial- use alternatives, but technologies labeled “provisional” or “piloting” remain prohibited.
Junghanns explained that allowing those newer systems would demand amendments to local regulations and a thorough legal review. MacCaughey added that “provisional” and “piloting” technologies have yet to prove their long-term reliability and are excluded under Wayland’s rules.
The Massachusetts Alternative Septic System Test Center in Barnstable County is a leading field site for monitoring and rigorously testing innovative alternative (I/A) on-site wastewater systems under real-world conditions. Junghanns and MacCaughey noted that MASSTC’s research — evaluating pollutant removal (nitrogen, pathogens, phosphorus) in sensitive waters — informs MassDEP’s certification decisions and often shapes local regulation. As Junghanns quipped, “It’s a pretty cool place to visit. “ Its demonstrations regularly guide towns like Wayland in adopting new septic technologies for general or remedial use.
Board members worried that tracking bedroom usage would be impractical and flow calculations would have to stick to the state’s baseline code. Junghanns warned that monitoring room conversions, verifying occupancy, and re-certifying on ownership changes would overwhelm the department, requiring legal reviews, inspections, and extra staff, and said offsets based on census or past use would be unenforceable without formal regulation changes and Town Counsel input. As member Jonathan Storer put it, a 40-year-old septic system could be “on the edge of failure” and unable to absorb a two-bedroom ADU by reconfiguring rooms alone.
Storer pointed out that a septic upgrade, even at $20,000–$60,000, is relatively small compared to a roughly $450,000 ADU build. He suggested simple, site-specific fixes, such as adding a 10-foot leach-line extension or installing a separate leach line opposite the existing system, could boost capacity without a complete replacement if site conditions allow. Board memers welcomed continued collaboration with the Housing Partnership on innovative solutions and offered to follow up in writing.
