Unincorporated County
Confirm the current County Environmental Health testing, notice, report, design, and submittal requirements before excavation.
San Bernardino County · California
Percolation testing and septic soil evaluation in San Bernardino County
A parcel-level guide to percolation testing, soil evaluation, onsite wastewater review, and septic planning across San Bernardino County—from the mountain communities and Inland Valley foothills to the High Desert, Morongo Basin, Mojave Desert, and Colorado River corridor.
Permitting path
Start with the parcel—not the mailing address
For an unincorporated parcel, San Bernardino County Environmental Health Services is normally the technical-review agency for an onsite wastewater treatment system. Inside an incorporated city or town, the project begins with that local jurisdiction and may also involve County Environmental Health, a sewer district, or the applicable Regional Water Quality Control Board.
The first practical question is whether public sewer is available or required. If an onsite system is allowed, the proposed home or use, grading, access, wells, drainage, setbacks, primary disposal area, and full replacement area all influence where testing should occur.
Incorporated city or town
Verify city limits, sewer availability, land-use requirements, and whether the city coordinates technical OWTS review with the County or another agency.
Sewer or special-service area
A service boundary, connection requirement, prohibition area, or special wastewater program can change the project path before a perc test is scheduled.
Water-quality oversight
California's statewide OWTS policy and the applicable Regional Water Board remain part of the regulatory framework, especially where local or mapped conditions require added review.
Understanding test results
There is no reliable city-wide or community-wide perc rate
San Bernardino County includes mountain rock, valley alluvium, desert fans, caliche, fine basin deposits, washes, fill, and shallow-groundwater settings. Those conditions can change within one parcel, so a nearby result or generalized soil map cannot establish the rate used for design.
Parcel-specific: Expected regional tendencies are useful for planning field access and test depth, but Calicore does not assign an expected rate to a town. The parcel's proposed primary and replacement areas must be evaluated in the field.
1–120 minutes per inch
The County's published design table covers measured leach-line rates from 1 through 120 minutes per inch. Results at either end still require soil-profile and site-condition review.
Primary plus replacement area
Testing and the concept layout must preserve the proposed dispersal area and the required replacement area after the building, grading, access, wells, and setbacks are located.
Soil profile controls too
Restrictive layers, groundwater, rock, slope, fill, drainage, and setbacks can control the project even when an individual percolation result appears workable.
Field-to-permit process
How percolation testing fits into the project
The exact sequence depends on jurisdiction and site conditions. A typical County-area residential project follows these stages.
- 01
Confirm jurisdiction and sewer status
Use the address or APN to identify city or County jurisdiction, sewer availability, special wastewater areas, the proposed use, and the reviewing agencies.
- 02
Review the site concept
Place the proposed building, grading, driveway, wells, drainage features, primary disposal area, and replacement area on a workable preliminary layout.
- 03
Plan and coordinate field work
Confirm current notice requirements, test locations and depths, excavation access, water supply, safety, and the field schedule before holes are opened.
- 04
Test and document the soil
Perform the applicable percolation procedure and record soil layers, limiting conditions, groundwater evidence, rock, fill, slope, and relevant site observations.
- 05
Prepare the agency work product
Compile the field data, site mapping, calculations, photographs, design basis, findings, and limitations needed for the next OWTS design or permit step.
County septic services
Continue from percolation testing into soil evaluation and system design.
Local planning guides
San Bernardino County community guides
Choose the closest project area for local soil and permitting context. Each guide is planning information; the exact authority, sewer status, field scope, and design criteria are confirmed for the parcel.
Central and Northern Mojave Desert19 guides+
Lower Colorado River and Eastern Desert7 guides+
Morongo Basin and East Desert14 guides+
San Bernardino and San Gabriel Mountains31 guides+
Agua FriaAngelus OaksArrowbear LakeBaldwin LakeBig Bear CityBig Bear LakeBlue JayCedar GlenCedarpines ParkCrest ParkCrestlineDeer Lodge ParkErwin LakeFawnskin / North ShoreForest FallsGreen Valley LakeLake ArrowheadLake GregoryLake WilliamsLytle CreekMoonridgeMountain Home VillageMt BaldyOak GlenRimforestRunning SpringsSkyforestSugarloafTwin PeaksValley of EnchantmentWrightwood
San Bernardino Valley and Foothills20 guides+
Victor Valley and High Desert14 guides+
Primary sources
Official rules and permitting information
Use these agency sources for planning, then confirm the current process for the parcel and proposed development. Forms, review responsibility, mapped service areas, and local procedures can change.
- Wastewater and land-use program San Bernardino County Environmental Health Services
- Local Agency Management Program San Bernardino County — County OWTS siting, design, operation, and management program.
- Percolation Testing and Reporting Standards San Bernardino County — Field procedures and report requirements currently linked by EHS.
- Onsite Wastewater Treatment Systems bulletin IB-00018 San Bernardino County Land Use Services — Construction-facing bulletin updated July 30, 2026.
- Water Quality Control Policy for Siting, Design, Operation and Maintenance of OWTS California State Water Resources Control Board
- Regional wastewater service area Big Bear Area Regional Wastewater Agency — Identifies the City of Big Bear Lake within the regional wastewater service area.
- Wastewater treatment City of Adelanto — City wastewater-system and treatment information.
- Apple Valley Local Agency Management Program for OWTS Town of Apple Valley / Lahontan Regional Water Quality Control Board — Town-specific OWTS permitting, siting, and management standards.
- Hesperia Local Agency Management Program for OWTS City of Hesperia / Lahontan Regional Water Quality Control Board — City-specific OWTS review and management standards.
- Supplemental Treatment System Program City of Hesperia — City information for parcels where a conventional OWTS may be constrained.
- Wastewater operations City of Barstow — City collection, treatment, and disposal information.
- Septic safety Twentynine Palms Water District — Local septic-use and groundwater-protection information.
- Wastewater project City of Twentynine Palms — Current City wastewater-project information.
- State septic discharge prohibition Hi-Desert Water District — Parcel- and phase-specific sewer-transition information.
- Septic systems Hi-Desert Water District — District information about septic systems and the sewer transition.
- Wastewater utility City of Needles — City collection, treatment, service, and septic-area information.
Common questions
San Bernardino County, California perc testing
Who reviews a perc test in San Bernardino County?+
For unincorporated County projects, San Bernardino County Environmental Health Services normally provides the technical OWTS review. Incorporated-city projects begin with the city and may also involve County Environmental Health, a sewer district, or a Regional Water Board. Confirm jurisdiction from the parcel before field work.
Can you estimate my property's perc rate from the town or ZIP code?+
No. Regional soil and geologic information can help plan an investigation, but the rate used for design must come from representative field testing in the proposed disposal areas together with the soil profile and site constraints.
Does a passing test guarantee a septic permit?+
No. Review also considers sewer availability, proposed flow, soil depth, groundwater and bedrock separation, slope, setbacks, grading, primary-system layout, and a compliant replacement area.
What should I send before requesting testing?+
Send the address or APN, any site or grading plan, the proposed use and bedroom count, known well or septic records, and agency comments. If you only have the property information, Calicore can help identify the likely next step.
Start with the property
Not sure what the agency needs?
Send the address or APN and whatever plans, records, or agency comments you already have. If you do not know the required service yet, an engineer can help identify the likely next step.
Ask about your site