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State guide

Septic companies in Montana

Montana splits septic between your county health department, which approves and permits the system, and the state, which reviews subdivisions. The line between them is drawn in acres: DEQ's subdivision review applies to parcels under twenty acres, and at twenty or more it does not. This guide covers both approvals and why you can need both at once, the contractor licence that replaced a registration in January, and what actually has to be disclosed when a property changes hands.

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104
Counties
28
With Google reviews
44

Who Regulates Septic Systems in Montana

Sources: Montana Department of Environmental Quality; Montana State Legislature. Checked 2026-09-18.

Montana has two authorities and one number decides whether you deal with both. Your county health department permits the system itself. The state gets involved through subdivision review, and the line it draws is drawn in acres rather than in gallons.

All residential septic systems are approved by your local health department, prior to installation, and DEQ tells you to contact the county sanitarian with questions opens in a new tab. The local board of health adopts regulations not less stringent than state standards for the control and disposal of sewage from private and public buildings opens in a new tab.

The twenty acre line is the one to check first, because it decides how many approvals your project needs. The DEQ Subdivision Program reviews divisions of land comprising less than 20 acres, as well as condominiums and recreational camping vehicle spaces opens in a new tab, because a subdivision means land divided so as to create parcels containing less than 20 acres opens in a new tab. At twenty acres or more, that review does not apply.

Below the line you need both approvals, not one instead of the other. DEQ puts it plainly: even though you have a certificate of subdivision approval, a drainfield permit is still required by the local health department opens in a new tab, and if the department approves the application it issues that certificate of subdivision approval opens in a new tab.

A county can do the state's review as well, if it is qualified, but there is a ceiling on that. A local department may conduct the review if it employs a registered sanitarian or a registered professional engineer and is certified competent opens in a new tab, while it may not review public water supply systems, public sewage systems, or extensions of or connections to them opens in a new tab. A public sewage system is one serving 15 or more families or 25 or more people daily opens in a new tab.

Licenses and What to Check Before You Hire

Sources: Jefferson County, Montana; Montana Department of Labor & Industry; Montana Department of Environmental Quality; Montana State Legislature. Checked 2026-09-18.

We found no statewide septic installer licence in Montana. What your installer must hold is set by your county, and separately by a general contractor law that changed in January.

That contractor law is new and worth checking a date on. The law transitioned the state's construction contractor system from a basic registration framework to an official licensing program opens in a new tab, and contractors that held an active Montana registration as of 31 December 2025 have been converted to the new licence opens in a new tab. So a card saying registration is not wrong, it is old.

Pumping is the one septic specific licence the state does issue. DEQ provides the forms to apply for a new Septic Tank Pumper License or to renew a current one opens in a new tab. Ask a pumping company for that licence rather than for a contractor credential.

The people who assess your ground hold professional registrations rather than a septic ticket. A qualified site evaluator means a soils scientist, professional engineer, registered sanitarian, hydrogeologist or geologist with the relevant experience opens in a new tab, and in Jefferson County the soil analysis during the site visit is conducted by a registered sanitarian, a licensed professional engineer or a licensed installer opens in a new tab.

Two of those titles are defined in statute, which tells you where to check them. A registered sanitarian is a person licensed to practise as a sanitarian under Title 37, chapter 40 opens in a new tab, and a registered professional engineer is licensed under Title 37, chapter 67 opens in a new tab.

We hold no Montana register of our own, so no listing here carries a verified credential for this state. The checks worth making are the county's installer list, the state contractor licence, and for a pumping company the DEQ pumper licence.

Permits, Inspections and Selling a Home

Sources: Jefferson County, Montana; Montana State Legislature; Montana Department of Environmental Quality. Checked 2026-09-18.

Work may not begin on the installation of a septic system until a completed wastewater system application and the applicable fee have been submitted opens in a new tab, and when the work is done the inspector files with the local board of health a certification that the system has been installed in compliance opens in a new tab. That certification is the record the county keeps of your system.

Below twenty acres there is a rule that stops everything until the state signs off. A person may not dispose of any lot within a subdivision, or erect any facility for the supply of water or disposal of sewage opens in a new tab before that approval exists. Older land can carry sanitary restrictions placed on subdivision lots before 1 July 1973 opens in a new tab, which are worth asking about on any inherited parcel.

On selling, we found no statewide rule requiring a septic inspection. Montana works through conditions carried forward on the title instead. Each subsequent seller of property within the subdivision shall include within the instruments of transfer a reference to the conditions opens in a new tab of the approval.

One kind of system does carry a disclosure duty of its own. Any person who sells a property containing an experimental system shall disclose all permit, monitoring and maintenance requirements to the buyer opens in a new tab. Ask which kind you are buying before you get to that point.

Keeping a System Working

Sources: Montana Department of Environmental Quality; U.S. Environmental Protection Agency. Checked 2026-09-18.

Montana's binding schedule applies to systems with moving parts rather than to a plain tank: an initial two year service policy must stipulate a minimum of 4 inspection and service visits, scheduled at least once every 6 months opens in a new tab, and notification to the local health department, and the service provider where appropriate, must be made within two business days if any unit fails opens in a new tab. For a conventional tank we found no state interval, so the EPA's inspection every three years and pumping every three to five applies opens in a new tab.

Help Paying for Repairs

Sources: Montana Department of Environmental Quality; Montana Department of Natural Resources and Conservation; Montana Department of Commerce; U.S. Environmental Protection Agency. Checked 2026-09-18.

We found no Montana fund a household can apply to directly for a septic repair. The state's nonpoint source programme requires an applicant to be a governmental entity or a nonprofit organisation opens in a new tab, and the two State Revolving Fund loan programmes lend to eligible Montana entities opens in a new tab.

One state administered route does reach a house, through your town or county rather than directly. Local governments are eligible to receive funds for the rehabilitation of single family owner occupied or rental units opens in a new tab, so ask whether yours is running a housing rehabilitation programme.

The standing federal route is the other one to ask about. It offers grants and low interest loans to repair, improve or modernise rural single family homes, with grants to elderly very low income owners opens in a new tab, while individual homeowners are not eligible to receive 319 grant assistance directly opens in a new tab.

Find Your County Health Department

Montana septic permits come from the county health department, and DEQ tells you to ask for the county sanitarian. The title varies: in Missoula the role is the land sanitarian, and in Yellowstone County the office is RiverStone Health rather than a county department. Each entry below is the office for that county. Checked 2026-09-18.

CountyEnvironmental health office
CascadeCity-County Health Department opens in a new tabThe office calls itself the City-County Health Department (CCHD) on the county's own .gov site; the board that adopts the rules is the City-County Board of Health. Cascade certifies septic installers itself: the page publishes a Certified Septic Installers list updated annually and says the permit fee depends on whether the septic installer is certified in Cascade County. CCHD moved septic permitting to a My Health Department online portal and will stop accepting paper applications on 1 October 2026. Site evaluation needs an 8 foot test hole with an Environmental Health Specialist on site, and a non-degradation analysis is required for new systems. · Cascade County page
MissoulaMissoula Public Health opens in a new tabAllowlisted .org, and the proof is a redirect rather than a link: https://www.missoulacounty.gov/permits-licenses/septic-permits/ redirects to this exact URL, and www.missoulapublichealth.gov redirects to the same .org host. The page's own title tag reads MissoulaPublicHealth.gov. The named role here is land sanitarian, not county sanitarian, and the sanitarian desk is closed to the public on Thursdays. The governing rule is the Missoula City-County Health Code, Regulation 1: Wastewater Treatment and Disposal Systems. Missoula requires four feet between drainfield and groundwater and groundwater monitoring must start by 1 April or wait for the next season. · Missoula County page
RavalliRavalli County Environmental Health opens in a new tabravalli.us redirects to ravallicounty.gov, so both hosts are the same county site and no allowlist is needed. The page abbreviates the office to RCEH and an RCEH representative must be present when the 8 to 12 foot soil test hole is dug. Confirms the Montana split the state research found: where DEQ has already approved the parcel through subdivision review the applicant supplies the DEQ approval, and where it has not the county runs the site evaluation itself. The application asks for the Name of Certified Installer (if known), which is the county installer field already known for Ravalli. Governing rule is the Ravalli County Subsurface Wastewater Treatment and Disposal Regulations (2021). · Ravalli County page
YellowstoneRiverStone Health Environmental Health Services opens in a new tabAllowlisted .org. Yellowstone County's own site, www.yellowstonecountymt.gov, lists no health department at all in its department directory and never mentions RiverStone, so the usual state-directory proof was not available from this box. What proves it: RiverStone's own Board of Health page says the RiverStone Health Board of Health sets public health policy for Yellowstone County, this page publishes the Rules and Regulations for On-Site Wastewater Treatment Systems In Yellowstone County, it hosts the Yellowstone County Licensed Septic Installers and Licensed Septic Pumpers lists, and its permit workflow routes the applicant through the Yellowstone County Courthouse, Room 305, for a Permit Tracking Sheet. Yellowstone licenses septic installers and pumpers at county level. Unusually, it also runs local subdivision review for parcels of 20 acres or more, the size class DEQ does not review. · Yellowstone County page

Questions People Ask

Who approves my septic system in Montana?

Your local health department. DEQ's own homeowner guidance says all residential septic systems are approved by the local health department before installation, and to contact the county sanitarian with questions.

When does the state get involved?

When the parcel is under twenty acres. The DEQ Subdivision Program reviews divisions of land comprising less than 20 acres, plus condominiums and recreational camping vehicle spaces. At twenty acres or more that review does not apply, and the county permit is the only one.

I have a certificate of subdivision approval. Is that my permit?

No. DEQ states that even though you have a COSA, a drainfield permit is still required by the local health department. They are two separate approvals and you need both.

Does my installer need a state licence?

We found no statewide septic installer licence. Counties set their own requirements, and separately every construction contractor now needs a Montana construction contractor licence: the law converted the old registration into a licence, and registrations active on 31 December 2025 were converted over.

Do I have to disclose anything when I sell?

There is no statewide inspection rule we could find, but each subsequent seller of property within a subdivision must reference the conditions of the approval in the instruments of transfer. If the system is an experimental one, the seller must disclose all permit, monitoring and maintenance requirements to the buyer.

Sources

Cities in Montana

Counties in Montana

How these are ranked

By verification score, out of 100, across six checks published in full on how we rank. No company paid to appear and none can pay to rank higher. The score counts records and is not a judgment about workmanship.