California ELAP
California environmental lab accreditation, ELAP and the TNI standard.
Who accredits your lab in California, which standard you are assessed against, how out-of-state labs qualify, and what auditors look for in your initial calibrations.
At a glance
How environmental lab accreditation works in California.
California runs its own program rather than acting as a NELAP accreditation body. Since January 1, 2024, that program requires labs to operate a quality system that meets the 2016 TNI Standard.
State program (non-NELAP)
- Program
- Environmental Laboratory Accreditation Program (ELAP), part of the Division of Drinking Water at the State Water Resources Control Board
- Legal basis
- Health and Safety Code section 100825 and following; accreditation regulations in Title 22, Division 4, Chapter 19 of the California Code of Regulations
- Quality system standard
- 2016 TNI Standard, Revision 2.1, Volume 1 (22 CCR 64802.05). The alternative quality assurance path ended January 1, 2024, so TNI compliance is now mandatory.
- Who needs it
- Labs that analyze environmental samples for regulatory purposes. Methods used only for internal process control are outside ELAP, and the Water Code exempts certain field tests such as pH, temperature and dissolved oxygen.
- Fields of accreditation
- Drinking water; non-potable water; environmental toxicity; hazardous waste (solids and chemical, and aqueous); pesticide residues in food; ambient water; air and soil vapor
- Out-of-state labs
- Must obtain California accreditation through reciprocity with a program at least as stringent as ELAP. For federal Safe Drinking Water Act fields, the primary accreditation must come from a state accreditation body.
- NELAP status
- Not a NELAP accreditation body. ELAP accredits to the TNI quality system standard under California rules.
The accreditation cycle
From application to renewal.
ELAP accredits by field of accreditation. The cycle below summarizes the program pages and regulations; your certificate and ELAP correspondence govern the specifics for your lab.
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Apply by field
Choose the fields of accreditation and methods your lab reports, and submit the application with your quality manual and supporting records.
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24-month accreditation
Initial and renewal accreditations each run for 24 months (22 CCR 64808.00 and 64808.05).
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Proficiency testing
At least one acceptable proficiency testing result per field of accreditation each year.
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On-site assessment
An on-site assessment within the two years before accreditation expires. ELAP staff or an approved third-party assessment agency may perform it, and labs using sophisticated technologies must use a third-party agency from ELAP’s approved list.
Initial calibration
What auditors check in your initial calibrations.
California has no separate calibration rule. The calibration requirements come from the TNI standard ELAP adopted and from the methods you are accredited for, so assessors work from the same questions as any TNI program.
A range that brackets what you report
The lowest standard should sit at or below your reporting limit and the highest at or above the top concentration you report. Results outside the calibrated range need to be qualified.
Error at the low end, not r² alone
A correlation coefficient of 0.999 can still hide a low standard that back-calculates 30 percent off. Auditors look at relative error, especially at the lowest levels.
Records that rebuild the curve
Raw responses, the model and weighting used, any excluded points with the reason, and the verification that followed. An auditor should be able to reconstruct every initial calibration from the record.
A quality system an assessor can audit
With TNI now mandatory, assessors check that your calibration procedures are written down, followed, and reviewed. A curve chosen differently by each analyst is a finding waiting to happen.
Source: 22 CCR 64802.05, 2016 TNI Standard Rev 2.1, Volume 1
Third-party assessors are approved to assess California labs, and they arrive with TNI checklists. A complete, consistent calibration record shortens that conversation.
Self-check
Are your initial calibrations ready for a California assessment?
Tick what your lab could show an auditor today. Nothing you select is saved or sent anywhere.
6Checks to work through
Select each item your lab could show an auditor today.
A self-assessment to help you prepare, not a compliance determination.
What changed
TNI became the rule in California in 2024.
ELAP’s current regulations took effect January 1, 2021, with a three year window in which labs could follow an alternative quality assurance program. That window closed on January 1, 2024. Every accredited lab now has to meet the 2016 TNI Standard, Revision 2.1, Volume 1, with two technical manager provisions excluded.
For many California labs that meant moving from method-by-method compliance to a full management and technical system. Calibration is where that shift is most visible: the method still sets the acceptance criteria, but the quality system has to show how the model was chosen, who reviewed it, and what happened when a standard failed.
The program continues to change. The State Water Board adopted ELAP fee amendments in September 2024 and emergency fee amendments in September 2026, ELAP now assesses asbestos methods, and the list of approved third-party assessors was revised in November 2025.
How WLTR helps
Calibration evidence ready for a California assessment.
WLTR independently reviews the calibration your instrument software produced. Your analyst still makes the final call. What changes is that the evidence is complete, consistent across analysts, and ready before the auditor asks for it.
- Each analyte reviewed one at a time in the instrument software.
- The model and weighting are whatever the batch was processed with.
- r² is the number most people look at, even though it does not measure error at the low end.
- QA signs off without an independent check on the curve.
- Every analyte and every candidate model side by side in the Calibration Intelligence dashboard.
- Diagnostics run automatically and the best fit curve is identified, with the reasons recorded.
- Relative error at every level, including the lowest standard, shown on one screen.
- A traceable record your QA manager can review, sign and hand to an ELAP assessor.
See how your own ICAL data looks when every analyte and model is laid out for review.
Questions
California accreditation FAQs
Is California a NELAP state?
No. California’s ELAP is a state program, not a NELAP accreditation body. It does, however, require accredited labs to meet the 2016 TNI Standard, Revision 2.1, Volume 1.
When did the TNI standard become mandatory in California?
January 1, 2024. The regulations took effect January 1, 2021 and allowed an alternative quality assurance program for three years. That option has now expired.
Can an out-of-state lab report data in California?
Yes, by obtaining California accreditation through reciprocity. ELAP must recognize the primary program as at least as stringent as its own, and for federal Safe Drinking Water Act fields the primary accreditation must come from a state accreditation body.
How long does ELAP accreditation last?
Initial and renewal accreditations each run for 24 months (22 CCR 64808.00 and 64808.05). Labs must also pass at least one proficiency test per field of accreditation each year and complete an on-site assessment within the two years before expiration.
Does ELAP have its own initial calibration rule?
No separate rule. Calibration requirements come from the TNI standard ELAP adopted and from each accredited method, so assessors look at range, low-level accuracy and whether the record lets them rebuild the curve.
Sources
Primary sources for this page.
- State Water Board, ELAP program home (opens in a new tab)
- ELAP regulations (opens in a new tab)
- ELAP frequently asked questions (opens in a new tab)
- ELAP laboratory assessments (opens in a new tab)
- ELAP proficiency testing (opens in a new tab)
- ELAP reciprocity application (SWRCB 243) (opens in a new tab)
This page summarizes public program information to help labs prepare. Requirements change, and the agency’s current rules and guidance always take precedence. WLTR is not affiliated with or endorsed by the California State Water Resources Control Board. Spot something out of date? Tell us at admin@wltr.tech.
Before your next assessment
See your California ICALs the way an assessor will.
Bring a recent initial calibration. We will walk you through every analyte and candidate model in the Calibration Intelligence dashboard, the best fit, and the record your QA manager would sign.
Request a demoHow the methodology works
Running environmental methods? See how WLTR works for environmental testing labs and water and wastewater utility labs.