Minnesota · Minn. R. 7080.1930
Septic system requirements in Minnesota
Tank sizes, drainfield rules, setbacks, permits, and real costs — pulled from Minnesota's own code rather than a national average.
- 3-bedroom tank
- 1,000 gal
- Design flow
- 150 gpd/BR
- Typical install
- $12,000–$30,000
- Permit fee
- $250–$900
- Well setback
- 50 ft
- Permitted by
- County / local
Septic tank sizes required in Minnesota
Minnesota sizes systems on a design flow of 150 gallons per day per bedroom. 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 | With garbage disposal |
|---|---|---|---|---|
| 1 bedroom | 150 gpd | 1,000 gal | 1,000 gal | 1,500 gal |
| 2 bedrooms | 300 gpd | 1,000 gal | 1,000 gal | 1,500 gal |
| 3 bedrooms | 450 gpd | 1,000 gal | 1,000 gal | 1,500 gal |
| 4 bedrooms | 600 gpd | 1,500 gal | 1,500 gal | 2,250 gal |
| 5 bedrooms | 750 gpd | 1,500 gal | 1,500 gal | 2,250 gal |
| 6 bedrooms | 900 gpd | 2,000 gal | 2,000 gal | 3,000 gal |
Source: Minn. R. 7080.1930. 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 Minnesota at 450 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 | 563 ft² | 1,126 ft² | $12,200 |
| Sandy loam | 0.5 gpd/ft² | 900 ft² | 1,800 ft² | $15,400 |
| Loam | 0.4 gpd/ft² | 1,125 ft² | 2,250 ft² | $17,500 |
| Silt loam | 0.3 gpd/ft² | 1,500 ft² | 3,000 ft² | $21,100 |
| Clay loam | 0.2 gpd/ft² | 2,250 ft² | 4,500 ft² | $28,200 |
Estimates use Minnesota's cost index of 1.06× the national average. Build a line-item estimate →
Permits and who issues them
Counties administer the SSTS program under MPCA Rules 7080–7083, and everyone who designs, installs, inspects, or pumps must hold an MPCA licence.
| Permit required | Yes |
|---|---|
| Typical fee | $250 – $900 |
| Soil evaluation | Required before permit |
| Licensed installer | Required |
| Turnaround | 2–6 weeks |
| Ongoing inspection | Compliance inspection required at property transfer and on permit applications |
| 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 | 50 ft |
|---|---|
| Property line | 10 ft |
| Surface water | 50 ft |
| Building foundation | 10 ft |
Regulatory contact
Minnesota Pollution Control Agency — Subsurface Sewage Treatment Systems
www.pca.state.mn.us · 651-296-6300
What makes septic hard in Minnesota
Deep frost means tanks and lines need real cover or insulation, and winter installation is effectively impossible.
Minnesota's three-foot vertical separation to the periodically saturated zone is strictly enforced and is what pushes so many sites to mound systems.
Lakeshore property faces both tight setbacks and shoreland nutrient rules.
Things that catch people out
- A garbage disposal requires 50% more tank capacity and multiple compartments. Minnesota is explicit about this where many states are silent.
- Minnesota requires a licensed professional at every step — designer, installer, inspector, and pumper all need separate MPCA licences.
- Systems classed as an "imminent threat to public health" must be fixed within 10 months.
Minnesota septic questions
What size septic tank do I need in Minnesota?
A three-bedroom home in Minnesota requires a minimum 1,000 gallon tank under Minn. R. 7080.1930. Design flow is 150 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 Minnesota?
Yes. Counties administer the SSTS program under MPCA Rules 7080–7083, and everyone who designs, installs, inspects, or pumps must hold an MPCA licence. Fees typically run $250 to $900, 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 Minnesota?
A conventional system for a three-bedroom home typically runs $12,000 to $30,000 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 Minnesota drainfield be from a well?
50 feet from a private water well. Local rules can be stricter.
Sources
Every figure on this page traces to one of these documents.
- Minn. R. 7080.1930 — Septic Tank Capacity · verified 2026-09-18
- Minn. R. ch. 7080 — Subsurface Sewage Treatment Systems · verified 2026-09-18