Utah · R317-4 · Utah Division of Water Quality
Utah sets a 1,000 gallon minimum tank and 150 gallons per bedroom per day design flow — but the real variables are your county health department, your soil, and whether your site is in a canyon, a valley, or near a sensitive water body.
Minimum tank
For one to three bedroom dwellings. Local health departments may require more.
Design flow
Held two days minimum for settling before discharge to the drainfield.
Governing rule
Utah Division of Water Quality. Local health departments issue permits.
Sandy loam is common on the Wasatch Front. Canyon areas often have shallow rock. Select closest match or ask your evaluator.
| Dwelling | Design flow | Minimum tank | With garbage disposal |
|---|---|---|---|
| 1 bedroom | 300 gpd | 1,000 gal | 1,250 gal |
| 2 bedrooms | 300 gpd | 1,000 gal | 1,250 gal |
| 3 bedrooms | 450 gpd | 1,000 gal | 1,250 gal |
| 4 bedrooms | 600 gpd | 1,250 gal | 1,500 gal |
| 5 bedrooms | 750 gpd | 1,500 gal | 1,750 gal |
| 6 bedrooms | 900 gpd | 2,000 gal | 2,250 gal |
Add one tank size for a garbage disposal in regular use. Hot tubs and water softeners discharging to the tank also increase the required capacity.
Soil conditions
Utah's geology varies more than almost any other state — your county and site location determine your system type and cost more than the state rule does.
Wasatch Front valleys
Coarse alluvial soils deposited by ancient Lake Bonneville drain quickly — often too quickly. Fast percolation rates mean effluent can reach groundwater before being treated. Many Wasatch Front sites require pressure distribution or enhanced treatment to protect the valley aquifer. Water table depth varies significantly across the valley floor.
Cache Valley
Lake-bottom clays left by prehistoric Lake Bonneville are tight and slow-draining. Percolation rates through Cache Valley clay are among the slowest in Utah, pushing drainfield sizes well above the state minimum. Pressure distribution is commonly required. The seasonal high water table in low-lying areas further constrains design.
Canyon and mountain areas
Shallow bedrock — granite, quartzite, and limestone — limits trench depth and drives up excavation costs dramatically. Hammer excavation or blasting is sometimes required. Summit County (Park City) enforces strict environmental standards on top of the physical difficulty. Short construction seasons at elevation add scheduling constraints and contractor premiums.
Washington County
Desert soils with caliche layers. Caliche is a cemented calcium carbonate layer that behaves like rock — impenetrable to water and requiring mechanical breaking. Where caliche sits at trench depth, conventional installation is slow and expensive. Desert soils themselves can drain fast or be layered with clay; a perc test on the specific parcel is essential before budgeting.
Heber Valley
A high mountain valley with a shallow water table that rises seasonally. Wasatch County Health Department enforces groundwater separation requirements strictly, and many Heber Valley sites need elevated or mound systems to achieve adequate separation. Growth pressure has intensified permitting scrutiny in recent years.
Uinta Basin
Semi-arid soils with variable percolation. Groundwater is generally deeper here than along the Wasatch Front, which eases separation requirements. However, caliche and clay layers appear in places. Rural lot sizes are typically larger, which helps with setback compliance.
By county
R317-4 sets the statewide floor. These counties are where local requirements most commonly exceed it, or where site conditions create the biggest design challenges.
| County | Permitting authority | What makes it different | Typical extra requirements |
|---|---|---|---|
| Salt Lake County | Salt Lake County Health Dept. | Dense suburban development, fast-draining alluvial soils over valley aquifer | Enhanced groundwater protection in some zones, strict setbacks from irrigation canals |
| Utah County | Utah County Environmental Health | Utah Lake watershed protection, Provo River proximity | Enhanced setbacks near Utah Lake, nitrogen management in sensitive areas, canyon restrictions |
| Summit County | Summit County Health Dept. | Park City and Snyderville Basin; shallow rock, short season, high values, strict environment | Advanced treatment often required, engineered designs standard, strict inspection schedule |
| Washington County | Southwest Utah Public Health Dept. | St. George growth corridor; caliche soil, desert conditions, rapid development | Caliche layer evaluation required, specific setbacks from Virgin River and tributaries |
| Wasatch County | Wasatch County Health Dept. | Heber Valley; shallow seasonal water table, growth pressure | Mound systems common, groundwater depth verification required |
| Cache County | Bear River Health Dept. | Logan area clay soils, Cache Valley inversion and air quality overlap | Large drainfields for clay, seasonal water table documentation |
| Davis County | Davis County Health Dept. | Suburban Wasatch Front between Salt Lake and Weber | Similar to Salt Lake County; aquifer protection in valley areas |
Installation cost
Utah has the widest cost range of almost any state because the terrain varies so dramatically. The same three-bedroom house costs very different amounts depending on where in Utah it sits.
| Region | System type | Typical installed cost | Main cost driver |
|---|---|---|---|
| Wasatch Front valleys Salt Lake, Davis, Weber |
Conventional or pressure dosed | $8,000 – $14,000 | Groundwater protection requirements, urban access |
| Utah Valley Utah County, Provo area |
Conventional, mound near Utah Lake | $9,000 – $16,000 | Lake setbacks, variable soils |
| Park City / Summit County | Advanced treatment, engineered | $18,000 – $35,000+ | Rock excavation, short season, strict county rules |
| Heber Valley Wasatch County |
Mound systems common | $14,000 – $22,000 | High water table, mound construction |
| St. George / Washington County | Conventional or caliche-adapted | $9,000 – $18,000 | Caliche breaking, desert conditions |
| Cache Valley Logan area |
Pressure distribution, large fields | $10,000 – $17,000 | Clay soils, large required field size |
| Pump-out service (statewide) | — | $290 – $520 | Tank size, access, lid depth |
Use the cost estimator for a detailed breakdown by bedroom count, soil type and system type. The replacement cost calculator covers existing system work.
Utah permitting runs through your local health department, not the state directly. The process follows R317-4 but each county adds its own scheduling, form requirements, and inspection standards.
Before any design work, a soil evaluation establishes what your site can support. Utah accepts percolation tests but most counties now prefer or require a soil morphology evaluation — a licensed evaluator reads the soil profile and determines the seasonal high water table. This step decides your system type and field size. Cost: $250 to $700 in most Utah counties; Summit County engineered evaluations run higher.
A design meeting R317-4 requirements is prepared based on the evaluation. For complex sites — canyon areas, high water table locations, sensitive watersheds — Summit and Wasatch counties typically require a stamped engineering design rather than a standard prescriptive design.
Submitted to your county health department with the soil evaluation report, site plan, and design. Utah County and Summit County applications require additional documentation for sensitive area sites. Budget two to four weeks for review; Summit County reviews can run longer.
Utah requires a licensed onsite wastewater installer. Homeowner installation is permitted on owner-occupied property in some circumstances but requires prior health department approval. In Summit and Wasatch counties, inspector notification requirements before breaking ground are enforced.
The local health department must inspect the open trenches and tank before any backfill. This is non-negotiable statewide. Backfilling before inspection results in an order to excavate — at the owner's expense.
A three-bedroom Utah home at 150 gallons per bedroom produces 450 gallons per day of design flow. What the drainfield looks like depends entirely on soil:
| Soil | Application rate | Field area needed | Trench length |
|---|---|---|---|
| Coarse alluvium (Wasatch Front) | 0.80 gpd/sq ft | 563 sq ft | 188 ft |
| Sandy loam | 0.60 gpd/sq ft | 750 sq ft | 250 ft |
| Loam | 0.45 gpd/sq ft | 1,000 sq ft | 333 ft |
| Silt loam (Cache Valley) | 0.30 gpd/sq ft | 1,500 sq ft | 500 ft |
| Clay loam | 0.20 gpd/sq ft | 2,250 sq ft | 750 ft |
Use the drainfield calculator to run your exact soil type and bedroom count. Most Utah counties require an equal-sized reserve area kept clear for a future replacement field.
Utah does not set a mandatory statewide pumping interval for conventional residential systems. The standard recommendation is every three to five years for a family of four on a 1,000 gallon tank. Summit County and Wasatch County advanced systems carry operation and maintenance agreements with reporting to the health department. Use the pump schedule calculator to find your interval by household size and tank capacity.
Verify before you build. The requirements above are compiled from Utah R317-4 and county programs for planning purposes. County health departments can and do require more than the state standard. Confirm all requirements with your local health department before designing or ordering equipment. Utah Division of Water Quality: deq.utah.gov/water-quality.
Utah questions
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