Septic System Design in Utah: Permits, Costs, and What to Expect
When You Need a Septic System
Many properties in Wasatch County, Summit County, and rural Utah aren't connected to municipal sewer. If that's your lot, a septic system is your wastewater solution — and it requires engineering, permitting, and testing before you can build.
The Design Process
1. Soil Testing (Perc Test)
A percolation test measures how quickly water drains through your soil. This determines:
- Whether your soil can support a septic system
- What type of system you need (conventional vs. alternative)
- The size of your leach field
2. Test Pit Excavation
A test pit allows the engineer to evaluate soil layers, depth to bedrock, and seasonal water table levels. This is critical in mountain areas where soil conditions vary dramatically.
3. System Design
Based on soil test results, your engineer designs a septic system that includes:
- Tank size (based on bedroom count, not square footage)
- Drain field layout and size
- Distribution method
- Setback requirements from wells, property lines, and water features
4. Permitting
Your septic design must be submitted to the local health department (Wasatch County Health Department, Summit County Health Department, etc.) for approval before your building permit can be issued.
Cost Breakdown
- Perc test & test pit: $500–$1,500
- Septic design: $1,300–$2,500
- Septic system installation: $12,000–$25,000
Complex systems (high groundwater, poor soil, 5+ bedrooms) push costs toward the higher end.
Common Pitfalls
- Designing before testing — Soil conditions may require a more expensive alternative system
- Undersizing the tank — Utah requires tanks sized by bedroom count, not bathrooms
- Ignoring setback requirements — Wells, property lines, and water features have strict setback rules
- Seasonal water table issues — High spring water tables can require mound or alternative systems
Pro Tip
Always complete your perc test and septic design before finalizing your home design. Soil conditions may dictate where your home can sit on the lot.
