Tier 1, Tier 2 or Tier 3: which set of rules your lot gets
Tier 1 is the default. Where no local program is approved, it governs new or replacement low-risk systems, capping design flow at 3,500 gallons a day and setting setbacks of 5 feet from property lines and structures and 100 feet from water wells. Once a Regional Water Board approves a county's Local Agency Management Program, that Tier 2 program supersedes Tier 1 for the agency until it's modified, withdrawn or revoked. Within 600 feet of an impaired water body on the policy's Attachment 2 list, a new or replacement system must meet Tier 3 unless a TMDL or the program's special provisions say otherwise. Ask the county's environmental health office which of these governs your parcel before anyone draws a design.
What one new system costs in California, and what our estimate leaves out
Our model puts a conventional gravity system at $4,225 to $13,900 per system, an estimate, not a quote, and the table gives alternative and engineered systems their own rows. One national range, scaled by the California operating engineer wage ratio, sets each of them with no California company sample to narrow it. None includes the county's permit fee.
| Item | Figure | What it is |
|---|---|---|
| Estimated range, conventional system, not a quote | $4,225 to $13,900 per system, conventional | A conventional gravity septic tank and drain field on a site with soil that percolates. Built from one national published range, adjusted by the California operating engineer wage ratio (1.42). Seven California companies publish a septic pumping price or typical range (only two print a firm $450) and one a $350 inspection; the pumping range is the middle half of those pumping prices, and a single inspection price is too few to move that estimate. Installation prices from three companies (from $5,000 in the Central Valley to $20,000 or more in the Sierra foothills) are recorded in the price file and not used. Basis: no state company sample (no counted California company price for this job), national estimate only. |
| Estimated range, alternative system, not a quote | $4,825 to $24,500 per system, alternative | An alternative system (pressure distribution, drip or sand filter) where soil or groundwater rules out a plain gravity field. Built from one national published range, adjusted by the California operating engineer wage ratio (1.42). Seven California companies publish a septic pumping price or typical range (only two print a firm $450) and one a $350 inspection; the pumping range is the middle half of those pumping prices, and a single inspection price is too few to move that estimate. Installation prices from three companies (from $5,000 in the Central Valley to $20,000 or more in the Sierra foothills) are recorded in the price file and not used. Basis: no state company sample (no counted California company price for this job), national estimate only. |
| Estimated range, engineered system, not a quote | $18,100 to $81,500 per system, engineered | A fully engineered system with a design, pump chamber and monitoring, as on difficult foothill or high-groundwater sites. Built from one national published range, adjusted by the California operating engineer wage ratio (1.42). Seven California companies publish a septic pumping price or typical range (only two print a firm $450) and one a $350 inspection; the pumping range is the middle half of those pumping prices, and a single inspection price is too few to move that estimate. Installation prices from three companies (from $5,000 in the Central Valley to $20,000 or more in the Sierra foothills) are recorded in the price file and not used. Basis: no state company sample (no counted California company price for this job), national estimate only. |
| Repairing or replacing a malfunctioning system (U.S. EPA, national) | $5,000 or more, up to about $15,000 | A national EPA figure for the whole system; not a California price and not a quote. |
Estimated ranges, one row per scope. Built from national published ranges (1 sources in all, 1 per row), adjusted by California's operating engineer wage ratio to the US (1.42, BLS May 2025). Not a quote. Seven California companies publish a septic pumping price or typical range (only two print a firm $450) and one a $350 inspection; the pumping range is the middle half of those pumping prices, and a single inspection price is too few to move that estimate. Installation prices from three companies (from $5,000 in the Central Valley to $20,000 or more in the Sierra foothills) are recorded in the price file and not used. Full method. Prices as of Oct 23, 2026.
Who may build it: CSLB's C-42 class and the local program
CSLB's class C-42, Sanitation System Contractor, fabricates and installs cesspools, septic tanks, storm drains and other sewage disposal and drain structures, including laying the related pipe. The local program has a say too, because the OWTS Policy requires each Local Agency Management Program to describe certification or licensing requirements for installers, designers and site evaluators. Check the license number on CSLB's Check a Contractor License page, which shows status, classification and bond. B&P 7044 exempts an owner who builds or improves a structure on their own property if the improvements aren't intended or offered for sale, subject to conditions in the section. Those conditions are in the section's text.
Two working days before the excavator digs
Government Code 4216.2 has the excavator notify the regional notification center at least two working days, and no more than 14 calendar days, before excavating, and the day of the notice doesn't count. Ask the installer who places that call, and on which day.
Loans the State Water Board points to
The State Water Board's funding page lists possible sources for private sanitary systems, USDA Rural Development programs among them. Section 14 of the OWTS Policy describes loan programs that local agencies can set up. Ask your county whether it runs one before you sign a bid.
When the old system won't hold until the new one's built
- Sewage is backing up into the house or pooling over the old tank or field.
- The old system still drains, which leaves time to get the county's tier answer and collect bids.
Before the first bid comes in
- Get the tier for your parcel from the county's environmental health office, along with its permit checklist.
- Write down each bidder's CSLB license number, then look up its classification and bond.
- Read B&P 7159.5 before paying a deposit: a home improvement contract must be in writing and signed before work starts, and the down payment may not exceed $1,000 or 10 percent of the contract price, whichever is less.
Which office permits a new system
Water Code 13290 names the local agency for onsite systems as a city, county, city and county, or special district, and 13291 has the State Water Board adopt the standards for permitting them. This page lists no county permit fee, so ask the environmental health office for its current one and whether the installer's bid includes it.
Questions people ask
Which agency issues a septic permit for a new system in California?
Water Code 13290 defines that local agency as a city, county, city and county, or special district, and 13291 directs the State Water Board to adopt standards for permitting onsite systems. The county's environmental health office can tell you which one handles your parcel.
What does CSLB's C-42 license cover?
CSLB lists class C-42, Sanitation System Contractor, for cesspools, septic tanks, storm drains and other sewage disposal and drain structures, including the related pipe. Look the number up on CSLB's Check a Contractor License page before you sign.
What will a new septic system cost in California?
That range comes from one national source scaled by California's operating engineer wage ratio, and the cost table lists alternative and engineered systems separately. The county's permit fee isn't in any of them, so ask for that number on its own.
- OWTS Policy sections 7-8 Read Oct 20, 2026.
- CSLB C-42 Sanitation System Contractor Read Oct 20, 2026.
- CSLB Check a License Read Oct 20, 2026.
- B&P 7044 Read Oct 20, 2026.
- Government Code 4216.2 Read Oct 20, 2026.
- State Water Board wastewater funding guidance Read Oct 20, 2026.
- U.S. Bureau of Labor Statistics, OEWS May 2025: Operating Engineers and Other Construction Equipment Operators (SOC 47-2073), California, mean hourly wage Read Oct 23, 2026.
- U.S. Bureau of Labor Statistics, OEWS May 2025: Operating Engineers and Other Construction Equipment Operators (SOC 47-2073), United States, mean hourly wage Read Oct 23, 2026.
- SepticMatch: how we estimate costs, California (editorial policy) Read Oct 23, 2026.
- EPA, Why maintain your septic system Read Oct 20, 2026.
- Water Code 13290-13291 (Chapter 4.5, Onsite Sewage Treatment Systems) Read Oct 20, 2026.
- B&P 7159 and 7159.5; CSLB contracts page Read Oct 20, 2026.