State guide
Montana
Montana handles onsite wastewater mainly through subdivision sanitation review: DEQ reviews subdivisions under 20 acres and sanitation facilities, but in contracted counties the application goes to the local health department. DEQ’s onsite standard requires a qualified site evaluator to conduct the site evaluation, and counties often run the practical permit and septic-record search tools residents use day to day.
Checked against official sources on October 4, 2026. Rules and links change; confirm with the office listed before you act.
Try a ZIP like 30303, “Travis County” or “Columbus, OH”
- Who regulates septic permits
- Montana onsite wastewater is regulated primarily by the Montana Department of Environmental Quality through subdivision sanitation review, with some counties contracted to perform review and local health departments often serving as the practical contact point.
- Who can do the soil or perc test
- Montana’s state standard says a qualified site evaluator conducts the site evaluation; DEQ 4 defines that role to include soils scientists, professional engineers, registered sanitarians, hydrogeologists, or geologists with appropriate experience and knowledge.
- State fee
- Not published by an official source we could verify. Ask the office.
Key facts for Montana
- DEQ reviews subdivisions under 20 acres for sanitation facilities including sewage disposal.
- If the subdivision is in a contracted county, the application must be submitted to the local health department.
- DEQ 4 says a qualified site evaluator shall conduct a site evaluation at each proposed system location.
- DEQ 4 defines a qualified site evaluator as a soils scientist, professional engineer, registered sanitarian, hydrogeologist, or geologist with experience and knowledge of soil.
- Montana publishes a subdivision review fee calculation, but not a single statewide flat septic-permit fee on the DEQ pages found.
County septic and soil-evaluation offices in Montana
| County office | city | phone | Details |
|---|---|---|---|
| Ravalli County Environmental Health - Wastewater System Permit Application Ravalli | Hamilton | Not published* | County septic permit application for new, replacement, or altered systems with Environmental Health contact details. |
| Ravalli County Environmental Health Ravalli | Hamilton | 406-375-6565 | County Environmental Health page referenced in Ravalli’s homebuyer septic guide for permits and copies of septic records. |
| Missoula City-County Health Department - SEWPER Query Missoula | Missoula | (406) 258-4755 | County septic-record and permit map showing septic, well, and site-evaluation records, with Health Department contact for parcel questions. |
* Not published: the official page doesn't list it. Call the office to confirm before you rely on it.
What to do next
- Ask first whether your parcel is part of a subdivision review, an exempt tract, or a county-level septic permit process.
- Hire a qualified site evaluator early; DEQ 4 makes that evaluation the basis for the proposed system location.
- In counties with their own septic programs, check the county permit or septic-record map before buying a rural lot.
Not seeing your county office or county?
Not every county office publishes its rules online. Try these, in order:
- General Start with the statewide information above.
- Closest verified Nearest places where we have verified local data outside this state (distance from Montana's population center, for comparison only):
- Park County Planning and Zoning Department - Small Wastewater Systems, Wyoming · about 192 miles
- Eastern Idaho Public Health — Teton County septic permitting contact, Idaho · about 210 miles
- Eastern Idaho Public Health — Bonneville County Environmental Health, Idaho · about 231 miles
- Call to confirm Ask the official office.Your city or county office: Local governments →Not sure who handles it locally? USAGov's free help line, 1-844-872-4681, or the Montana page on USA.gov can point you to the right office.
- Know the current info? Tell us with a link to the official page.