North Carolina DEQ and SLPH
North Carolina environmental lab certification, DEQ and the State Lab.
Which North Carolina agency certifies your lab, why NELAP accreditation does not substitute for state certification, how reciprocity works, and the calibration rules in the code.
At a glance
How environmental lab certification works in North Carolina.
North Carolina is not a NELAP state. Two agencies certify environmental labs under their own rules, and DEQ does not accept NELAP accreditation in place of its certification.
State program (non-NELAP)
- Wastewater and groundwater
- Laboratory Certification Branch, Water Sciences Section, Division of Water Resources, NC Department of Environmental Quality. The branch certifies around 700 labs.
- DEQ rule
- 15A NCAC 02H .0800, readopted July 1, 2019, with 02H .0804 amended effective September 1, 2024 and January 1, 2026
- Who needs DEQ certification
- Labs that generate data reported to the State under the water quality statutes. Labs must certify each parameter method used to produce reported data. Field labs are certified for field parameters only.
- Drinking water
- Laboratory Certification, Environmental Sciences, State Laboratory of Public Health, NC Department of Health and Human Services, under 10A NCAC 42D, for labs analyzing public water system samples
- NELAP status
- Not a NELAP accreditation body. DEQ states it does not recognize NELAP accreditation issued by other agencies in lieu of its own certification.
- Out-of-state labs, DEQ
- Reciprocal certification is available under 15A NCAC 02H .0809. DEQ states that reciprocity removes the initial on-site inspection, but it is not guaranteed.
- Out-of-state labs, drinking water
- Labs must be certified by their home state or EPA, and an initial on-site inspection is conducted at the lab’s expense (10A NCAC 42D .0236)
The accreditation cycle
The DEQ certification cycle.
The steps below summarize 15A NCAC 02H .0800 for wastewater and groundwater labs. Drinking water labs follow the State Lab’s separate schedule under 10A NCAC 42D.
-
Certify by parameter method
Choose the certification type (municipal, industrial, commercial, field and others) and certify each parameter method used to produce reported data.
-
Proficiency testing
One PT sample per parameter method per year (02H .0805), with graded results due to the branch by September 30.
-
Inspections
Periodic announced or unannounced inspections.
-
Annual renewal
Certificates are issued for one year, with renewals due January 1.
Initial calibration
What auditors check in your initial calibrations.
Because North Carolina writes its own rules, the calibration expectations are in the code and in the Laboratory Certification Branch’s policies rather than in a TNI module.
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.
Standard counts set in the rule
15A NCAC 02H .0805 requires colorimetric curves with at least five non-zero standards if prepared every 12 months, or at least three if prepared daily, and daily balance checks with a standard weight.
Source: 15A NCAC 02H .0805
The Laboratory Certification Branch also publishes calibration policies, including Correlation Coefficient for Linear Calibration Curves, Factory Set Curve Verification and Second Source Standard. Check the current versions on the branch’s policies page.
Self-check
Are your initial calibrations ready for a North Carolina 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.
North Carolina specifics
A NELAP certificate is not a North Carolina certificate.
Labs that already hold NELAP accreditation elsewhere should plan for this. DEQ is explicit that it does not recognize NELAP accreditation in lieu of its own certification. Reciprocity is possible, and it waives the initial on-site inspection, but the lab is still certified to North Carolina’s rule, parameter method by parameter method.
That rule is specific. It sets standard counts for colorimetric curves, balance checks, and PT deadlines, and the branch’s policies add detail on correlation coefficients, factory-set curves and second-source standards. An auditor compares your records to those documents, not to a TNI checklist.
The rule keeps expanding. PFAS methods were added to 02H .0804 effective September 1, 2024, and total nitrogen and the pharmaceutical pollutant methods in 40 CFR 136.3 Table IF were added effective January 1, 2026.
How WLTR helps
Calibration evidence ready for a North Carolina inspection.
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 a state auditor.
See how your own ICAL data looks when every analyte and model is laid out for review.
Questions
North Carolina accreditation FAQs
Is North Carolina a NELAP state?
No. Neither NC DEQ nor the State Laboratory of Public Health is a NELAP accreditation body, and DEQ does not accept NELAP accreditation in place of its own certification.
Who certifies wastewater labs in North Carolina?
The Laboratory Certification Branch of the Division of Water Resources, NC Department of Environmental Quality, under 15A NCAC 02H .0800.
Who certifies drinking water labs in North Carolina?
The State Laboratory of Public Health, NC Department of Health and Human Services, under 10A NCAC 42D.
Does North Carolina offer reciprocity?
DEQ offers reciprocal certification under 15A NCAC 02H .0809 when the other program meets North Carolina’s requirements, which waives the initial on-site inspection. Reciprocity is not guaranteed. For drinking water, out-of-state labs must be certified by their home state or EPA and receive an initial on-site inspection at their own expense.
What does North Carolina require for calibration curves?
15A NCAC 02H .0805 requires at least five non-zero standards for colorimetric curves prepared every 12 months, or three if prepared daily. The Laboratory Certification Branch also publishes calibration policies on correlation coefficients and second-source standards.
Sources
Primary sources for this page.
- NC DEQ, Laboratory Certification Branch (opens in a new tab)
- NC DEQ, non-field laboratory certification (opens in a new tab)
- NC DEQ, certification rules and regulations (opens in a new tab)
- NC DEQ, Laboratory Certification Branch policies (opens in a new tab)
- NC State Laboratory of Public Health, laboratory certification (opens in a new tab)
- 15A NCAC 02H .0805, laboratory certification requirements (opens in a new tab)
- 10A NCAC 42D .0236, out-of-state laboratories (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 North Carolina Department of Environmental Quality or the NC Department of Health and Human Services. Spot something out of date? Tell us at admin@wltr.tech.
Before your next assessment
See your North Carolina ICALs the way an auditor 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.