Chapter 17.5. Lead and Copper. Monitoring for Lead and Copper. Determination of Exceedances of Lead and Copper Action Levels.
(a) The detection limits for purposes of reporting (DLRs) for lead and copper are as follows:
Table 64678-A. DLRs for Lead and Copper
Contaminant DLR (mg/L)
(b) For purposes of determining the difference in concentration between the source water and the 90th percentile tap results, the following shall apply:
(1) Analytical results for lead greater than or equal to 0.001 mg/L and less than 0.005 mg/L shall be as measured or 0.0025 mg/L, whichever is greater.
(2) Analytical results for copper greater than or equal to 0.001 mg/L and less than 0.050 mg/L shall be as measured or 0.025 mg/L, whichever is greater.
(3) Analytical results below 0.001 mg/L for lead and copper shall be considered zero.
(c) Analytical results below the DLRs for lead and copper specified shall be reported as zero.
(d) The lead action level is exceeded if the concentration of lead in more than 10 percent of the tap water samples collected during any period is greater than 0.015 mg/L (i.e., if the "90th percentile" lead level is greater than 0.015 mg/L).
(e) The copper action level is exceeded if the concentration of copper in more than 10 percent of the tap water samples collected during any period is greater than 1.3 mg/L (i.e., if the "90th percentile" copper level is greater than 1.3 mg/L).
(f) The 90th percentile lead and copper levels shall be computed as follows:
(1) The results of all lead or copper samples collected during a period shall be placed in ascending order from the sample with the lowest concentration to the sample with the highest concentration. Each sampling result shall be assigned a number, ascending by single integers beginning with the number 1 for the sample with the lowest contaminant level. The number assigned to the sample with the highest contaminant level shall be equal to the total number of samples taken.
(2) The number of samples taken during the period shall be multiplied by 0.9.
(3) The contaminant concentration in the numbered sample identified by the calculation in paragraph (f)(2) is the 90th percentile contaminant level.
(4) For water systems serving less than or equal to 100 people that collect 5 samples per period, the 90th percentile is computed by taking the average of the highest and second highest concentrations.
(g) The results of any monitoring conducted in addition to the minimum requirements of this section shall be considered by the system and submitted to the department for making any determinations.
Health and Safety Code 100275
Health and Safety Code 116350
Health and Safety Code 116365
Health and Safety Code 116375
Health and Safety Code 116385
Health and Safety Code 116325-116750
(Added by Register 2003, No. 37.)