Maine · 10-144 C.M.R. Ch. 241
Septic system requirements in Maine
Tank sizes, drainfield rules, setbacks, permits, and real costs — pulled from Maine's own code rather than a national average.
- 3-bedroom tank
- 1,000 gal
- Design flow
- 90 gpd/BR
- Typical install
- $10,000–$26,000
- Permit fee
- $250–$700
- Well setback
- 100 ft
- Permitted by
- County / local
Septic tank sizes required in Maine
Maine sizes systems on a design flow of 90 gallons per day per bedroom, with every dwelling rated for at least 2 bedrooms. The tank must meet both the bedroom table below and a 2× daily-flow detention requirement — whichever produces the larger number governs.
| Bedrooms | Design flow | Code minimum | Recommended |
|---|---|---|---|
| 1 bedroom | 180 gpd | 1,000 gal | 1,000 gal |
| 2 bedrooms | 180 gpd | 1,000 gal | 1,000 gal |
| 3 bedrooms | 270 gpd | 1,000 gal | 1,000 gal |
| 4 bedrooms | 360 gpd | 1,250 gal | 1,250 gal |
| 5 bedrooms | 450 gpd | 1,500 gal | 1,500 gal |
| 6 bedrooms | 540 gpd | 1,750 gal | 2,000 gal |
Source: 10-144 C.M.R. Ch. 241. The recommended column rounds the governing requirement up to a tank size manufacturers actually stock.Run your own numbers →
Drainfield size and cost by soil type
For a three-bedroom home in Maine at 270 gpd. This single table explains most of the variation between quotes — the area scales inversely with how fast your soil accepts water, and the drainfield is the largest line item in the job.
| Soil | Loading rate | Absorption area | With reserve | Typical total install |
|---|---|---|---|---|
| Medium sand | 0.8 gpd/ft² | 338 ft² | 676 ft² | $9,100 |
| Sandy loam | 0.5 gpd/ft² | 540 ft² | 1,080 ft² | $10,900 |
| Loam | 0.4 gpd/ft² | 675 ft² | 1,350 ft² | $12,000 |
| Silt loam | 0.3 gpd/ft² | 900 ft² | 1,800 ft² | $14,000 |
| Clay loam | 0.2 gpd/ft² | 1,350 ft² | 2,700 ft² | $17,900 |
Estimates use Maine's cost index of 0.97× the national average. Build a line-item estimate →
Permits and who issues them
Municipal Local Plumbing Inspectors issue permits from a design prepared by a state-licensed Site Evaluator, under Maine CDC rules.
| Permit required | Yes |
|---|---|
| Typical fee | $250 – $700 |
| Soil evaluation | Required before permit |
| Licensed installer | Required |
| Turnaround | 2–6 weeks |
| Ongoing inspection | Not mandated statewide |
| Reserve area | 100% replacement area required |
Minimum setback distances
Measured horizontally from the drainfield unless noted. Local rules are frequently stricter, and on a small lot these numbers — not the soil — often decide the layout.
| Private water well | 100 ft |
|---|---|
| Well (septic tank) | 50 ft |
| Property line | 10 ft |
| Surface water | 100 ft |
| Building foundation | 10 ft |
Regulatory contact
Maine CDC — Subsurface Wastewater Unit
www.maine.gov · 207-287-5695
What makes septic hard in Maine
Shallow bedrock and glacial till mean ledge blasting is a routine line item in much of the state.
Shoreland zoning around lakes and the coast imposes setbacks well beyond the base rule and is strictly enforced.
Deep frost penetration requires careful burial depth and insulation on shallow components.
Things that catch people out
- Only a licensed Site Evaluator can produce the HHE-200 design form. No form, no permit — and evaluators book out weeks ahead in summer.
- Since 2023 every tank must have a watertight riser to finished grade, which adds cost on older replacement jobs.
Maine septic questions
What size septic tank do I need in Maine?
A three-bedroom home in Maine requires a minimum 1,000 gallon tank under 10-144 C.M.R. Ch. 241. Design flow is 90 gallons per day per bedroom, and the tank must also hold 2 times daily flow, so the practical recommendation is 1,000 gallons.
Do I need a permit for a septic system in Maine?
Yes. Municipal Local Plumbing Inspectors issue permits from a design prepared by a state-licensed Site Evaluator, under Maine CDC rules. Fees typically run $250 to $700, with a turnaround of about 2–6 weeks. A soil evaluation or percolation test is required before a permit is issued.
How much does a septic system cost in Maine?
A conventional system for a three-bedroom home typically runs $10,000 to $26,000 installed. Soil quality moves this more than anything else — on tight clay requiring a mound, budget two to three times the low end.
How far must a Maine drainfield be from a well?
100 feet from a private water well, with the septic tank itself allowed at 50 feet. Local rules can be stricter.
Sources
Every figure on this page traces to one of these documents.
- 10-144 C.M.R. Ch. 241 — Maine Subsurface Wastewater Disposal Rules · verified 2026-09-27
- 10-144 C.M.R. Ch. 241 (2023) — Subsurface Wastewater Disposal Rule · verified 2026-09-18