Utah · Utah Admin. Code R317-4-6
Septic system requirements in Utah
Tank sizes, drainfield rules, setbacks, permits, and real costs — pulled from Utah's own code rather than a national average.
- 3-bedroom tank
- 1,000 gal
- Design flow
- 150 gpd/BR
- Typical install
- $8,000–$22,000
- Permit fee
- $250–$900
- Well setback
- 100 ft
- Permitted by
- County / local
Septic tank sizes required in Utah
Utah sizes systems on a design flow of 150 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 1.5× daily-flow detention requirement — whichever produces the larger number governs.
| Bedrooms | Design flow | Code minimum | Recommended |
|---|---|---|---|
| 1 bedroom | 300 gpd | 1,000 gal | 1,000 gal |
| 2 bedrooms | 300 gpd | 1,000 gal | 1,000 gal |
| 3 bedrooms | 450 gpd | 1,000 gal | 1,000 gal |
| 4 bedrooms | 600 gpd | 1,000 gal | 1,000 gal |
| 5 bedrooms | 750 gpd | 1,250 gal | 1,250 gal |
| 6 bedrooms | 900 gpd | 1,500 gal | 1,500 gal |
Source: Utah Admin. Code R317-4-6. 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 Utah 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 | $10,700 |
| Sandy loam | 0.5 gpd/ft² | 900 ft² | 1,800 ft² | $13,600 |
| Loam | 0.4 gpd/ft² | 1,125 ft² | 2,250 ft² | $15,400 |
| Silt loam | 0.3 gpd/ft² | 1,500 ft² | 3,000 ft² | $18,600 |
| Clay loam | 0.2 gpd/ft² | 2,250 ft² | 4,500 ft² | $24,900 |
Estimates use Utah's cost index of 0.93× the national average. Build a line-item estimate →
Permits and who issues them
Local health departments issue permits under Utah DEQ rule R317-4; DEQ reviews systems above 5,000 gpd.
| Permit required | Yes |
|---|---|
| Typical fee | $250 – $900 |
| 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
Utah Division of Water Quality — Onsite Wastewater
deq.utah.gov · 801-536-4300
What makes septic hard in Utah
Wasatch Front growth has pushed development onto benches with shallow bedrock and steep slopes.
Groundwater along the valley floors is shallow and closely monitored for nitrate.
Rural southern Utah has caliche and rock that make excavation the dominant cost.
Things that catch people out
- An unfinished basement counts as at least one additional bedroom in Utah. This catches a lot of people building with a future basement finish in mind.
- The minimum design flow is 300 gpd for one or two bedrooms, so small homes are not sized small.
Utah septic questions
What size septic tank do I need in Utah?
A three-bedroom home in Utah requires a minimum 1,000 gallon tank under Utah Admin. Code R317-4-6. Design flow is 150 gallons per day per bedroom, and the tank must also hold 1.5 times daily flow, so the practical recommendation is 1,000 gallons.
Do I need a permit for a septic system in Utah?
Yes. Local health departments issue permits under Utah DEQ rule R317-4; DEQ reviews systems above 5,000 gpd. 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 Utah?
A conventional system for a three-bedroom home typically runs $8,000 to $22,000 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 Utah 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.
- Utah Admin. Code R317-4-6 — Design Requirements · verified 2026-09-18
- Utah Admin. Code R317-4 — Onsite Wastewater Systems · verified 2026-09-18