California
Soil Percolation (Perc) Test
Perc and deep hole soil testing to determine whether land can support a septic system, and what type.
What the work involves
A percolation test measures how fast water drains into soil; many jurisdictions also require deep hole test pits to inspect soil layers and the seasonal high water table. Tests may be performed by a septic contractor, soil scientist or engineer, often witnessed by the health department. Results determine whether a lot is buildable without sewer and what septic system it needs.
Local conditions we plan for
- High seismic hazard and active faults
- Wildfire in the wildland urban interface
- Landslides and debris flows on steep slopes
- Coastal bluff erosion and sea level rise
Building code: California Building Standards Code (Title 24), based on the 2024 IBC and IRC, statewide (ICC adoption chart, April 2026).
When you need it
- Buying land without public sewer
- Applying for a septic permit
- Planning a lot split
- Replacing a failed septic system
Frequently asked questions
How much does soil Percolation (Perc) Test cost?
Across the US, soil Percolation (Perc) Test usually costs $200 to $3,000 per test. HomeGuide reports $200 to $1,500 for hand-dug tests and $500 to $3,000 or more for excavator tests; HomeAdvisor gives $750 to $1,900 (average $1,300). An engineer adds $200 to $500 per HomeGuide.
How long does soil Percolation (Perc) Test take?
Plan on 1 to 4 weeks, seasonal in some states from signed proposal to stamped deliverables, longer if a site visit, soil testing or a permit review cycle is involved.
Do I need a licensed PE for soil Percolation (Perc) Test?
In most US jurisdictions, yes. When the work needs a permit, the plans, calculations or report usually must be sealed by a Professional Engineer licensed in the state where the project is located. Every deliverable we issue for permit is sealed that way.
How do I verify an engineer's license in California?
Engineers practicing in California are licensed by the Board for Professional Engineers, Land Surveyors, and Geologists (BPELSG). You can confirm a license number and its status in the board's public license search before you sign a contract.
Which building code applies in California?
California Building Standards Code (Title 24), based on the 2024 IBC and IRC, statewide (ICC adoption chart, April 2026). Cities and counties can add local amendments, which is one reason to hire an engineer who works in your area.
What site problems do engineers see most in California?
Common issues include high seismic hazard and active faults, wildfire in the wildland urban interface, landslides and debris flows on steep slopes and coastal bluff erosion and sea level rise.