90th percentile level definition
90th percentile level means that concentration of lead or copper contaminant exceeded by ten percent or fewer of all samples collected during a six-month monitoring period pursuant to Section 611.356 (i.e., that concentration of contaminant greater than or equal to the results obtained from 90 percent of the samples). The 90th percentile levels for copper and lead must be determined pursuant to subsection (c)(3) of this Section.
90th percentile level means that concentration of lead or copper contaminant exceeded by ten percent or fewer of all samples collected during a six-month monitoring period under Section 611.356 (i.e., that concentration of contaminant greater than or equal to the results obtained from 90 percent of the samples). The 90th percentile levels for copper and lead must be determined under subsection (c)(3).