New Hampshire Code of Administrative Rules
Env - Department of Environmental Services
Subtitle Env-Ws - Division of Water
Chapter Env-Ws 300 - NEW HAMPSHIRE DRINKING WATER RULES
Part Env-Ws 380 - FILTRATION, DISINFECTION, TREATMENT PLANT AND WASTE RECYCLING
Section Env-Ws 380.25 - Disinfection Profiling for Systems Which Serve Less than 10,000 People
Current through Register No. 13, March 27, 2025
(a) The owner of a community or non-transient non-community public water system subject to the requirements of Env-Ws 380.23 and which serves fewer than 10,000 people shall comply with the requirements in (b) through (d) below.
(b) The system shall develop a disinfection profile unless the department determines that the system's profile is unnecessary. The department shall determine that a system's profile is unnecessary if a system's TTHM and HAA5 levels are below 0.064 mg/L and 0.048 mg/L, respectively.
(c) In accordance with 40 CFR 141.531, to determine whether a disinfection profile is required, TTHM and HAA5 samples shall be collected as follows:
(d) The department shall approve the use of a more representative data set for disinfection profiling than the data set required under Env-Ws 380.25(e).
(e) A system owner required to profile under (b) above shall conduct disinfection profiling as follows:
(f) A system owner may submit a written request to the department to use existing operational data in lieu of the monitoring conducted under the provisions of (e) above.
(g) The written request shall include the following:
(h) The data specified in (e) above shall be representative of giardia lamblia inactivation through the entire treatment plant and not just of certain treatment segments.
(i) The department shall determine whether the operational data is substantially equivalent to data collected under the provisions of (e) above.
(j) Until the department approves the request identified in (g) above, the system owner shall conduct monitoring under the provisions of (e), above.
(k) To develop a disinfection profile, a system owner shall calculate the total inactivation ratio as follows:
(l) The owner of a system that uses chloramines, chlorine dioxide, or ozone for primary disinfection shall also calculate the logs of inactivation for viruses and develop an additional disinfection profile for viruses using methods approved by the department.
(m) Each log inactivation shall serve as a data point in a system disinfection profile.
(n) The system owner shall collect and retain disinfection profile data in the form of a graphor as a spreadsheet and have the data available when the department conducts a sanitary survey pursuant to Env-Ws 306.
#5098, eff 3-18-91, EXPIRED 3-18-97
New. #6521, eff 6-4-97 (See Revision Note at chapter heading for Env-Ws 300); ss by #8352, eff 5-14-05 (formerly part of Env-Ws 380.28 )