Quick answer: A new septic system in Massachusetts requires a soil evaluation (perc test), a design by a registered engineer or sanitarian, a Board of Health permit, installation by a locally permitted installer, and a final inspection that results in a Certificate of Compliance.
The process, step by step
- Soil evaluation. A MassDEP-approved soil evaluator digs deep observation holes and runs a percolation test, usually with the Board of Health agent witnessing. Results set the system size and location.
- Design. A registered professional engineer or registered sanitarian designs the system to Title 5 standards, based on design flow (110 gallons per day per bedroom), setbacks from wells, wetlands and property lines, and groundwater depth.
- Permit. The Board of Health reviews the plan and issues a disposal system construction permit. Variances or Conservation Commission review may be needed near wetlands.
- Installation. A licensed installer (with a permit from that town) builds the tank, distribution box and soil absorption system.
- Inspection & Certificate of Compliance. The designer and Board of Health inspect before backfill, and the town issues a Certificate of Compliance.
System types you may hear about
- Conventional: tank, d-box and gravity leach field
- Pressure-dosed or pump systems: needed when the field is uphill or uses pressure distribution
- Mounded systems: raised fields used where groundwater is high
- I/A (innovative/alternative): extra treatment, often nitrogen removal, sometimes required near sensitive waters
Timeline
Installation often takes days. Soil testing, design and permitting typically take weeks, and longer if your town restricts perc testing to certain seasons or a variance is needed. Start early if you're planning a sale or construction.
Related guides
Frequently asked questions
How much does a new septic system cost in Massachusetts?
Conventional systems commonly run about $15,000–$40,000+, and mounded or I/A systems more. See our cost guide for the factors that drive price.
What is a perc test?
A percolation test measures how fast water soaks into your soil. Together with deep observation holes, it tells the designer how large the leach field must be and where it can go.
Can I install my own septic system in Massachusetts?
Generally no. Towns require a permitted installer, and the system must be designed and inspected to Title 5 standards.
Last reviewed 2026-11-09. Regulations and prices change. Confirm details with your local Board of Health and your contractor.