Section Env-Ws 382.12 - Monitoring for Disinfectant Residuals: Chlorine, Chloramine and Chlorine Dioxide(a) An owner of a community or non-transient non-community water system using chlorine or chloramines shall conduct routine monitoring for chlorine or chloramines by measuring residual disinfectant levels at the same time and at the same points in the distribution system as total coliform samples are collected as specified in Env-Ws 325.(b) In lieu of collecting separate samples, a SW/GWUDISW system owner may use the results of residual disinfectant concentration sampling conducted as follows: (1) As specified in Env-Ws 380.22(a) for unfiltered water systems; or(2) As specified in Env-Ws 380.22(b) for filtered water systems.(c) An owner of a community, non-transient non-community, or transient non-community water system using chlorine dioxide for disinfection or for oxidation shall collect at least one routine sample per day at the entrance to each distribution system.(d) For any daily sample that exceeds the chlorine dioxide MRDL specified in Env-Ws 317.80, the system owner shall:(1) Continue to collect at least one daily sample at each entrance to the distribution system as specified in (c) above; and(2) Collect additional samples in the distribution system the day following the exceedance as follows:a. If chlorine dioxide or chloramines are used to maintain a disinfectant residual in the distribution system, or if chlorine is used to maintain a disinfectant residual in the distribution system and there are no disinfection addition points after the entrance to the distribution system, such as no booster chlorination, the system owner shall collect 3 samples as close to the first customer at the entry to the distribution system as possible, at intervals of at least 6 hours; andb. If chlorine is used to maintain a disinfectant residual in the distribution system and there are one or more disinfection addition points after the entrance to the distribution system, such as booster chlorination, the system owner shall collect one sample at each of the following locations:1. As close to the first customer in the distribution system as possible;2. In a location within the distribution system representative of average residence time; and3. At the end of the distribution system, reflecting maximum residence time in the distribution system.(e) Chlorine, chloramines, and chlorine dioxide monitoring shall not be reduced.N.H. Code Admin. R. Env-Ws 382.12
(See third Revision Note at chapter heading Env-Ws 300); #7735, eff 8-2-02