Section 58.01.17.601 - MUNICIPAL RECYCLED WATER: CLASSIFICATION, TREATMENT, USE01.Class A Recycled Water. To be classified Class A recycled water, municipal wastewater must be treated using processes identified in Table 1, or an equivalent process, and adequately disinfected. Class A treatment systems are reviewed by the Department and approved on a case-by-case basis. The Department may require pilot testing or demonstration before approval, or may condition approval upon the success of testing or demonstration.a. Total Coliform. i. Recycled water must be disinfected by either:(1) Chlorine disinfection process following filtration that provides a CT (the product of concentration and modal contact time measured at the same point) of four hundred and fifty (450) milligram-minutes per liter (mg-min/L) measured at the end of the contact time based on total chlorine residual and a modal contact time of not less than ninety (90) minutes based on maximum day flow; or(2) Disinfection process that, when combined with filtration, has been demonstrated to achieve 5-log removal/inactivation of virus. Acceptance by the State of California as published in their Alternative Treatment Technology Report for Recycled Water is one (1) method to constitute such a demonstration.ii. Median number of total coliform organisms may not exceed two and two-tenths (2.2) per one hundred (100) milliliters, as determined from the bacteriological results of the last seven (7) days for which analyses have been completed. No sample may exceed twenty-three (23) organisms per one hundred (100) milliliters.iii. Daily sample and analyze recycled water for total coliform when allowed uses specifically require Class A recycled water.b. Turbidity. i. Recycled water must meet the following turbidity limits before disinfection:(1) For filtration systems using sand or other granular media or cloth media, the daily arithmetic mean of all measurements of turbidity may not exceed two (2) NTU, and turbidity may not exceed five (5) NTU at any time.(2) For filtration systems using membrane filtration, the daily arithmetic mean of all measurements of turbidity may not exceed zero point two (0.2) NTU, and turbidity may not exceed zero point five (0.5) NTU at any time.ii. One (1) in-line, continuously monitoring, recording turbidimeter exists for each treatment train after filtration and before disinfection.c. Nitrogen, pH, and BOD5.i. Total nitrogen may not exceed ten (10) milligrams per liter (mg/L) for ground water recharge systems and thirty (30) mg/L for residential irrigation and other non-recharge uses based on a monthly arithmetic mean as determined from weekly composite sampling. If a ground water quality impact assessment indicates lower limits are necessary to protect existing ground water quality beneficial uses, the Department will require lower limits.ii. The pH as determined by daily grab samples or continuous monitoring must be between six point zero (6.0) and nine point zero (9.0).iii. BOD5 may not exceed five (5) mg/L for ground water recharge systems, and ten (10) mg/L for residential irrigation and other non-recharge systems, based on a monthly arithmetic mean as determined from weekly composite sampling.02.Class B Recycled Water. To be classified Class B recycled water, municipal wastewater must be treated using processes identified in Table 1, or an equivalent process, and adequately disinfected. Class B treatment systems are reviewed by the Department and approved on a case-by-case basis. The Department may require pilot testing or demonstration before approval, or may condition approval upon the success of testing or demonstration. a. Total Coliform. i. Recycled water must be disinfected by either:(1) Chlorine disinfection process that provides a residual chlorine at the point of compliance of not less than one (1) mg/L total chlorine residual after a contact time of thirty (30) minutes at peak hour flow; or(2) An alternative disinfection process that has been demonstrated to the Department's satisfaction that the alternative process is comparable to that achieved by chlorination with a total chlorine residual of one (1) mg/L after a minimum contact time of thirty (30) minutes.ii. Median number of total coliform organisms may not exceed two and two-tenths (2.2) per one hundred (100) milliliters, as determined from the bacteriological results of the last seven (7) days for which analyses have been completed. No sample exceeds twenty-three (23) organisms per one hundred (100) milliliters.iii. Daily sample and analyze recycled water for total coliform when allowed uses specifically require Class B recycled water.b. Turbidity. i. Daily arithmetic mean of all measurements of turbidity may not exceed five (5) NTU, and turbidity may not exceed ten (10) NTU at any time. The turbidity standard is met before disinfection.ii. One (1) in-line, continuously monitoring, recording turbidimeter exists for each treatment train after filtration and before disinfection.03.Class C Recycled Water. To be classified Class C recycled water, municipal wastewater must be treated using the processes identified in Table 1.a. Median number of total coliform organisms may not exceed twenty-three (23) per one hundred (100) milliliters, as determined from the bacteriological results of the last five (5) days for which analyses have been completed. No sample may exceed two hundred thirty (230) per one hundred (100) milliliters.b. Weekly sample and analyze recycled water for total coliform when allowed uses specifically require Class C recycled water.04.Class D Recycled Water. To be classified Class D recycled water, municipal wastewater must be treated using the processes identified in Table 1. a. Median number of total coliform organisms may not exceed two hundred thirty (230) per one hundred (100) milliliters, as determined from the bacteriological results of the last three (3) days for which analyses have been completed. No sample may exceed two thousand three hundred (2300) organisms per one hundred (100) milliliters.b. Monthly sample and analyze recycled water for total coliform when allowed uses specifically require Class D recycled water.05.Class E Recycled Water. To be classified Class E recycled water, municipal wastewater must be treated with screening, degritting, sedimentation and/or skimming processes to remove substantially all floatable and settleable solids. a. Class E recycled water has no disinfection requirements or applicable coliform standard.b. No sampling and analysis of total coliform are required for Class E recycled water. When sampling and analysis are required (e.g., buffer distance change reduction), the sampling frequency for total coliform will be established consistent with these rules to adequately protect human health and the environment.06.Point of compliance. For total coliform limits, the point in the system following final treatment and disinfection as defined in the permit. Recycled water disinfection requirements after storage will be determined by the Department on a case-by-case basis considering class and uses of recycled water, reuse site design, and protection of human health and the environment.07.Alternative Monitoring Frequency. Alternative total coliform monitoring frequencies may be considered by the Department on a case-by-case basis based upon demonstration that the alternative frequency is protective of human health and the environment.Idaho Admin. Code r. 58.01.17.601