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 380.14 - Monitoring Requirements for Systems That Do Not Provide Filtration

Universal Citation: NH Admin Rules Env-Ws 380.14

Current through Register No. 13, March 27, 2025

(a) The owner of a public water system that uses a surface water source and does not provide filtration treatment shall monitor as specified in this section.

(b) The owner of a public water system that uses a ground water source under the direct influence of surface water and does not provide filtration treatment shall monitor as specified in this section beginning 6 months after the department determines that the ground water source is under the direct influence of surface water unless the department has determined that filtration is required pursuant to Env-Ws 380.04, in which case the system shall monitor according to Env-Ws 375.10 until filtration is in place.

(c) Fecal coliform or total coliform density measurements shall be performed on representative source water samples immediately prior to the first or only point of disinfectant application as follows:

(1) Each week the system serves water to the public, the system shall sample for fecal or total coliforms at the minimum frequency specified in Table 380-1:

Table 380-1

Sampling Non-filtered Systems for Coliforms

System Size (persons served) (shall be taken on separate days) Samples/Week
<500 1
501 - 3,300 2
3,301 - 10,000 3
10,001 - 25,000 4
>25,000 5

(2)One fecal or total coliform density measurement shall be made every day the system serves water to the public and the turbidity of the source water exceeds 1 NTU; and

(3) The fecal or total coliform density measurements made according to (2) shall count toward the weekly coliform sampling requirement required by (1).

(d) Turbidity measurements as required by Env-Ws 380.06 shall be performed on representative grab samples of source water immediately prior to the first or only point of disinfectant application every 4 hours, or more frequently, that the system serves water to the public.

(e) A public water system may substitute continuous turbidity monitoring for grab sample monitoring if it validates the continuous measurement for accuracy on a regular basis using a protocol recommended by the equipment manufacturer.

(f) The total inactivation ratio for each day that the system is in operation shall be determined based on the CT99.9 values in Tables 380-2 through Table 380-9 of Env-Ws 380.15, as applicable.

(g) The parameters necessary to determine the total inactivation ratio shall be monitored as follows:

(1)The temperature of the disinfected water shall be measured at least once per day at each residual disinfectant concentration sampling point;

(2) If the system uses chlorine, the pH of the disinfected water shall be measured at least once per day at each chlorine residual disinfectant concentration sampling point;

(3) The disinfectant contact time(s) shall be determined for each day during peak hourly flow;

(4) The residual disinfectant concentration(s) of the water before or at the first customer shall be measured each day during peak hourly flow;

(5) If a system uses a disinfectant other than chlorine, the system shall demonstrate to the department, through the use of on-site disinfection challenge studies or other information that CT99.9 values other than those specified in Tables 380-8 and 380-9 in this section other operational parameters are adequate to demonstrate that the system is achieving the minimum inactivation rates required by Env-Ws 380.10;

(6) The CT values in Tables 380-2 through 380-7 shall be assumed to achieve greater than a 99.99 percent inactivation of viruses;

(7) CT values between the indicated pH values shall be determined by linear interpolation;

(8) CT values between the indicated temperatures of different tables shall be determined by linear interpolation;

(9) If no interpolation is used, the CT99.9 value at the lower temperature and at the higher pH shall be used;

(10) The CT values in Table 380-8 shall be assumed to achieve greater than 99.99 percent inactivation of viruses;

(11) CT values between the indicated temperatures shall be determined by linear interpolation;

(12) If no interpolation is used, the CT99.9 value at the lower temperature in Table 380-8 for determining CT99.9 values between indicated temperatures shall be used;

(13) The CT values in Table 380-9 shall be assumed to achieve greater than 99.99 percent inactivation of viruses only if chlorine is added and mixed in the water prior to the addition of ammonia; and

(h) If the condition is not met as specified in (g) above, the system owner shall demonstrate, based on on-site studies or other information that the system is achieving at least 99.99 percent inactivation of viruses. CT values between the indicated temperatures shall be determined by linear interpolation. If no interpolation is used, the CT99.9 value at the lower temperature for determining CT99.9 values between indicated temperatures shall be used.

#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 380.22 )

Disclaimer: These regulations may not be the most recent version. New Hampshire may have more current or accurate information. We make no warranties or guarantees about the accuracy, completeness, or adequacy of the information contained on this site or the information linked to on the state site. Please check official sources.
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.