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 380.23 - Enhanced Filtration and Disinfection

Universal Citation: NH Admin Rules Env-Ws 380.23

Current through Register No. 13, March 27, 2025

(a) Unless otherwise specified, the requirements in Env-Ws 380.23 through Env-Ws 380.28 shall apply to:

(1) SW/GWUDISW systems serving at least 10,000 people,; and

(2) Pursuant to 40 CFR 141.70(e), beginning January 1, 2005, systems serving fewer than 10,000 people.

(b) The requirements in this section shall establish or extend treatment technique requirements in lieu of maximum contaminant levels for the following contaminants:

(1) Giardia lamblia;

(2) Viruses;

(3) Heterotrophic plate count bacteria;

(4) Legionella;

(5) Cryptosporidium; and

(6) Turbidity.

(c) The owner of a SW/GWUDISW system shall provide treatment of the source water that complies with treatment technique requirements identified in (d) below, and as specified in Env-Ws 380.04.

(d) The treatment technique requirements shall consist of installing and properly operating water treatment processes as follows:

(1) For a filtered system, at least 99%, or 2-log removal of cryptosporidium shall be achieved between a point where the raw water is not subject to recontamination by surface water runoff and a point downstream before, or at the first customer;

(2) For an unfiltered system, control of cryptosporidium shall be achieved by using the watershed control plan as specified in Env-Ws 380.23(e)(1); and

(3) Compliance with the profiling and benchmark requirements shall be achieved under the provisions of Env-Ws 380.24 through Env-Ws 380.26.

(e) The owner of a public water system subject to the requirements of this section shall be in compliance with Env-Ws 380.03(a) if:

(1) The system meets:
a. The requirements for avoiding filtration set forth in Env-Ws 380.05 through Env-Ws 380.08 and(g) through (i) below; and

b. The disinfection requirements set forth in Env-Ws 380.19 through Env-Ws 380.10 and Env-Ws 380.24 though Env-Ws 380.26; or

(2) The system meets:
a. The applicable filtration requirements set forth in Env-Ws 380.12 and Env-Ws 380.27; and

b. The disinfection requirements in Env-Ws 380.11, Env-Ws 380.24, and Env-Ws 380.25.

(f) A system owner shall not construct an uncovered finished water storage facility.

(g) In addition to the requirements of Env-Ws 380.05 through Env-Ws 380.08, the owner of a public water system subject to the requirements of this section that does not provide filtration shall comply with the watershed control program specified in Env-Ws 380.07(e) to minimize the potential for contamination by cryptosporidium oocysts in the source water.

(h) The watershed control program identified in (g) above, shall, for cryptosporidium:

(1) Identify watershed characteristics and activities which might have an adverse effect on source water quality; and

(2) Monitor the occurrence of activities which might have an adverse effect on source water quality.

(i) During the on-site inspection conducted under Env-Ws 380.07(g), the department shall use the criteria specified in Env-Ws 380.07(e)(1) through (4) to determine whether the watershed control program established under Env-Ws 380.07(e) is adequate.

(j) As required by 40 CFR 141.70(e), a SW/GWUDISW system that served fewer than 10,000 people as of January 1, 2002, but served at least 10,000 people as of January 1, 2005, shall:

(1) Comply with all the requirements in Env-Ws 380.23 through 380.27 for systems serving at least 10,000 people;

(2) Consult with the department to establish a disinfection benchmark; and

(3) If a significant change is made to the disinfection practice, consult with the department prior to making such change as specified in Env-Ws 380.24.

#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 Env-Ws 380.27 )

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