Maine · Maine Subsurface Wastewater Disposal Rules
Maine DHHS writes the rules; Licensed Site Evaluators design systems and municipal Local Plumbing Inspectors issue permits.
Minimum tank
One to three bedroom dwelling.
Design flow
Held two days for settling.
Cost index
Regional labour and permits.
Sets the design flow and the legal minimum.
Code sizes on bedrooms, not people.
Used to size the matching drainfield. Unsure? Sandy loam is the common default.
Glacial till over granite bedrock, with ledge at shallow depth across much of the state. Coastal and lakefront lots are small, old, and heavily constrained by setbacks. Frost depth is significant.
Maine relies heavily on the Licensed Site Evaluator to design the system, and engineered fill systems are extremely common because native soil depth over ledge is so often inadequate.
| Dwelling | Design flow | Minimum tank | With disposal |
|---|---|---|---|
| 1 bedroom | 300 gpd | 1,000 gal | 1,250 gal |
| 2 bedrooms | 300 gpd | 1,000 gal | 1,250 gal |
| 3 bedrooms | 450 gpd | 1,000 gal | 1,250 gal |
| 4 bedrooms | 600 gpd | 1,250 gal | 1,500 gal |
| 5 bedrooms | 750 gpd | 1,500 gal | 1,750 gal |
Maine's system is distinctive: the Licensed Site Evaluator both evaluates the soil and designs the system, producing an HHE-200 application. There is no separate designer step for most residential work.
The state sets a floor. These Maine counties are where the largest septic populations sit, and where local requirements most often exceed it.
| County | What makes it different |
|---|---|
| Cumberland | Portland area; growth pressure, mixed soils |
| York | Coastal development, small older lots |
| Penobscot | Bangor area, till over ledge |
| Oxford | Rural, rocky, large lots |
| Hancock | Coastal and island lots with severe constraints |
A three-bedroom home at 150 gallons per bedroom produces 450 gallons per day of design flow. On sandy loam that needs roughly 750 square feet of absorption area. On clay loam it rises to about 2,250 square feet, and on clay a conventional field is usually not permitted at all. Run your own soil class through the drainfield calculator.
No statewide mandated interval; frequent pumping is advised given cold soil temperatures. Use the pump schedule calculator to work out the interval for your tank size and household.
Regional labour and permit costs in Maine run about 112% of the national baseline. Here is what typical installations land at for a three-bedroom home:
| System type | Typical installed cost in Maine | When it applies |
|---|---|---|
| Conventional gravity | $10,100 – $17,900 | Good soil, adequate depth to water |
| Chamber system | $11,100 – $20,600 | Alternative to gravel trenches |
| Mound system | $19,200 – $37,600 | Shallow water table or thin soil |
| Aerobic treatment | $16,200 – $32,200 | Clay soil or small lots |
| Tank pump-out (service) | $360 – $730 | Every 3–5 years |
Replacing an existing system costs more than these figures — old-system removal and re-permitting add to every line. The replacement cost calculator covers that case, and the cost estimator adjusts all of the above for your bedroom count and soil.
Verify before you build. The figures above are state minimums compiled for planning, drawn from Maine Subsurface Wastewater Disposal Rules, 10-144 CMR Chapter 241. County and health district rules routinely exceed them, code text changes, and only Maine DHHS — Subsurface Wastewater Program or your local health department can confirm what applies to your parcel.
Send your sizing numbers to installers who work under Maine rules every day.