Haw. Code R. § tit. 11, subtit. 1, ch. 20, app B
Type of System | Minimum Monitoring Frequency | Sample Location in the distribution system |
Subpart H system serving at least 10,000 persons. | Four water samples per quarter per treatment plant. | At least 25 per-cent of all samples collected each quarter at locations representing maximum residence time. Remaining samples taken at locations representative of at least average residence time in the distribution system and representing the entire distribution system, taking into account number of persons served, different sources of water, and different treatment methods1. |
Subpart H system serving from 500 to 9,999 persons. | One water sample per quarter per treatment plant. | Locations representing maximum residence time1. |
Subpart H system serving fewer than 500 persons. | One sample per year per treatment plant during month of warmest water temperature. | Locations representing maximum residence time1. If the sample (or average of annual samples, if more than one sample is taken) exceeds MCL, system must increase monitoring to one sample per treatment plant per quarter, taken at a point reflecting the maximum residence time in the distribution system, until system meets reduced monitoring criteria in HAR § 11-20-45.1(c)(2)(A)(iv). |
System using only ground water not under direct influence of surface water using chemical disinfectant and serving at least 10,000 persons. | One water sample per quarter per treatment plant2. | Locations representing maximum residence time1. |
System using only ground water not under direct influence of surface water using chemical disinfectant and serving fewer than 10,000 persons. | One sample per year per treatment plant2 during month of warmest water temperature | Locations representing maximum residence time1. If the sample (or average of annual samples, if more than one sample is taken) exceeds MCL, system must increase monitoring to one sample per treatment plant per quarter, taken at a point reflecting the maximum residence time in the distribution system, until system meets criteria in HAR § 11-20-45.1(c)(2)(A)(iv). |
1If a system elects to sample more frequently than the minimum required, at least 25 percent of all samples collected each quarter (including those taken in excess of the required frequency) must be taken at locations that represent the maximum residence time of the water in the distribution system. The remaining samples must be taken at locations representative of at least average residence time in the distribution system.
2Multiple wells drawing water from a single aquifer may be considered one treatment plant for determining the minimum number of samples required, with State approval in accordance with criteria developed under HAR § 11-20-45.1(c)(1)(B).
Haw. Code R. tit. 11, subtit. 1, ch. 20, app B