Septic System Replacement cost in Great Falls, MT
Great Falls, MT · updated August 2026
$13,700
Typical local cost
$7,600 – $28,400
Typical range
- per system replaced
- $7,600 – $28,350
- Permit
- Yes
- Typical timeline
- 3-7 days of work
Installed, local pricing
$310 – $1,055 in fees
3-7 days of work, 4-10 weeks including health department review
Great Falls runs +1% against the U.S. average · data confidence Medium · modeled estimate, not a quote
The modeled midpoint for Great Falls is $13,700. The local adjustment for this trade is x1.013 — driven mainly by Cascade County labor rates and 80% exposure to local code requirements.
Cost by project size
Generated from the same unit pricing the calculator uses.
| Project size | Estimated range |
|---|---|
| 2-bedroom drainfield | $6,100 – $22,700 |
| 3-bedroom system | $7,600 – $28,400 |
| 4-bedroom system | $9,500 – $35,500 |
| Mound or aerobic system | $12,200 – $45,400 |
Based on Great Falls pricing of $7,600–$28,350 per system replaced.
Where the money goes
- Labor
- $7,500
- 52% of median
- Materials
- $6,200
- 43% of median
- Permit & fees
- $685
- 5% of median
Great Falls project costs+1% vs U.S. average
Based on Cascade County labor rates, local material logistics and permit-fee posture for this trade.
What the project looks like start to finish
Typical sequence for this scope. Timing varies with contractor backlog and plan-review queues.
01
Planning & quotes
Scope, material choice, contractor selection
02
Permit application
Filed with City of Great Falls building department
03
Materials & staging
Order lead time on non-stock materials
04
Installation
3-7 days of work, 4-10 weeks including health department review
05
Inspection
Soil / site evaluation, Tank set inspection, Drainfield inspection, Final cover inspection
06
Closeout
Final sign-off, warranty and documentation
Great Falls labor intelligence
What the trade charges here, and how much of your price it is.
Loaded hourly rate
$92–$120
Plumbing crews in Cascade County · 0% vs U.S. ($105/hr)
Typical crew
3 × 3 days
On-site time for a typical septic job here.
Labor in the price
$7,500
55% of the median — the rest is material, disposal and permit.
Because labor is 55% of this job, Great Falls wage levels move the price far more than material prices do. A quote well under this labor figure usually means a smaller crew, a longer schedule, or unlicensed help.
Basis: Hometriva labor model: national plumbing crew rates adjusted by the Cascade County labor factor (x1.000). · BLS Occupational Employment and Wage Statistics, Hometriva methodology
Why Great Falls differs from the national average
The local delta, broken into dollars by driver.
Material and delivery+$100
Materials are nationally traded, so they move less — but delivery into this market runs 2% over baseline.
Permit fees-$100
Fees are paid to the jurisdiction, not the contractor, and are budgeted separately from the contract price.
Code and inspection load+$75
Septic System Replacement carries 80% exposure to local code requirements, and this jurisdiction's review load indexes at x1.01.
Basis: Decomposition of the modeled Great Falls median against the U.S. median for this scope. · City of Great Falls building department, Hometriva methodology
Great Falls vs Montana vs the U.S.
Change the inputs, see your number
The same local model, run against your job instead of the average one.
Simulated septic system replacement in Great Falls
$14,385
Likely range $8,285 – $29,085
Simulated from the same local model as the numbers above — it changes the inputs, not the pricing method.
What makes the number move
- Tank size based on bedroom count
- Conventional versus mound or performance-based system
- Soil conditions and water table depth
- Lot access for equipment
- Abandonment of the old tank
Who issues each permit
Tracked per discipline — the building permit issuer is not always the body that reviews electrical, plumbing, zoning or fire.
| Discipline | Issuing authority |
|---|---|
| building | City of Great Falls building departmentModeled estimate |
| electrical | City of Great Falls building departmentModeled estimate |
| mechanical | City of Great Falls building departmentModeled estimate |
| plumbing | City of Great Falls building departmentModeled estimate |
| zoning | City of Great Falls building departmentModeled estimate |
| fire | City of Great Falls building departmentModeled estimate |
Permit requirement in Great Falls
Yes — a permit is required for septic system replacement in Great Falls, MT. The work must be inspected before it can be closed out, and a licensed contractor generally has to pull the permit.
- Permitting authority
- City of Great Falls building departmentModeled estimate
- Permit fee
- Estimated allowance $310–$1,055Modeled from comparable fee schedules — not an official quoted fee.
Inspections
- Soil / site evaluation
- Tank set inspection
- Drainfield inspection
- Final cover inspection
Local conditions that change this job
Only the exposures that materially affect septic system replacement.
Flood zone exposure
Moderate50/100
Annual rainfall
High74/100
Nearby market comparison
What Great Falls homeowners actually paid
Homeowner-reported invoices for this market. Nothing is published until enough reports clear review, so this section is often empty in newer markets — adding yours takes 20 seconds and no personal details.
Quotes homeowners were given in Great Falls
Quotes run ahead of final invoices. Reporting yours shows the local spread and where there is room to negotiate.
How Hometriva estimates Great Falls septic costs
Hometriva does not publish invented city prices. The Great Falls estimate for septic system replacement is produced by this chain, and every input is stored separately:
- National baseline$13,500
Typical U.S. cost for septic system replacement on a single-family home.
- Local labor factorx1.000
Great Falls-area trade labor rates, weighted at 55% of this job.
- Material factorx1.016
Material and delivery pricing into Cascade County, weighted at 45%.
- Regulatory factorx1.007
Local code, product-approval and inspection load, applied at 80% for this project type.
- Applied multiplierx1.013
Blended Great Falls adjustment specific to septic system replacement.
- Permit component$310 – $1,055
Budgeted separately from the contract price because it is paid to the jurisdiction.
Because labor, material and regulatory factors are weighted per project, septic system replacement in Great Falls carries a different local adjustment than other trades in the same market.
Reviewed by
Hometriva Cost Data Desk
Maintains the unit-cost baselines, local adjustment factors and material pricing. Reviewed for septic system replacement pricing in Great Falls, MT.
- • National unit-cost baselines against current trade pricing
- • Local labor and materials factors for the market
- • Material installed-cost ranges and service life
Last reviewed August 2026 · Editorial standards · Report an error
Frequently asked questions
Do I need a permit for septic system replacement in Great Falls, MT?
In most jurisdictions this work is permitted and inspected. Requirements are set locally, so confirm the current application and inspection checklist with your building department before work starts.
How long does septic system replacement take?
3-7 days of work, 4-10 weeks including health department review. Permit review and inspection scheduling are usually the largest source of variation.
What changes the price the most?
The largest cost drivers are tank size based on bedroom count; conventional versus mound or performance-based system; soil conditions and water table depth.
Sources
Sources & verification
Model vintage August 2026. The links above are the issuing agencies' own pages — we publish them so you can confirm the current rule yourself, not as evidence that each fact on this page was re-checked with them today. Cost figures are modeled estimates based on national baselines adjusted for local labor and material pricing, not quotes. Permit rules change; confirm with the building department before starting work.