Section 179-13-005 - DISINFECTION A public water system that uses a ground water source under the direct influence of surface water and does not provide filtration treatment must provide disinfection treatment specified in 179 NAC 13-005.01 beginning 18 months after the Director determines that the ground water source is under the direct influence of surface water. If filtration is required in accordance with 179 NAC 13-006, the system must comply with any interim disinfection requirements the Director deems necessary before filtration is installed. A system that uses a surface water source and provides filtration treatment must provide the disinfection treatment specified in 179 NAC 13-005.02 beginning June 29, 1993, or beginning when filtration is installed, whichever is later. A system that uses a ground water source under the direct influence of surface water and provides filtration treatment must provide disinfection treatment as specified in 179 NAC 13-005.02 by June 29, 1993, or beginning when filtration is installed, whichever is later. Failure to meet any requirement of 179 NAC 13-005 is a treatment technique violation.
005.01 Disinfection Requirements for Public Water Systems That Do Not Provide Filtration Each public water system that uses a ground water source under the direct influence of surface water and does not provide filtration treatment must provide disinfection treatment as follows:
13-005.01A The disinfection treatment must be sufficient to ensure at least 99.9% (3-log) inactivation of Giardia lamblia cysts and 99.99% (4-log) inactivation of viruses, every day the system serves water to the public, except any one day each month. Each day a system serves water to the public, the public water system must calculate the CT value(s) from the system's treatment parameters, using the procedure specified in 179 NAC 13-007.02D and determine whether this value(s) is sufficient to achieve the specified inactivation rates for Giardia lamblia cysts and viruses. If a system uses a disinfectant other than chlorine, the system owner may demonstrate to the Director that CT( 99.9) values other than those specified in Tables 13.7 and 13.8 in 179 NAC 13-007.02C or other operational parameters are adequate to demonstrate that the system is achieving minimum inactivation rates required by 179 NAC 13-005.13-005.01B The disinfection system must have either redundant components, including an auxiliary power supply with automatic start-up and alarm to ensure that disinfectant application is maintained continuously while water is being delivered to the distribution system, or automatic shut-off of delivery of water to the distribution system whenever there is less than 0.2 milligrams (mg) per liter of residual disinfectant concentration in the water. If the Director determines that automatic shut-off would cause unreasonable risk to health or interference with fire protection, the system must have the above redundant components.13-005.01C The residual disinfectant concentration in the water entering the distribution system, measured as specified in 179 NAC 13-007.01B and 13-007.02E cannot be less than 0.2 mg per liter for more than four hours.13-005.01DResidual Disinfectant Concentration13-005.01D1 The residual disinfectant concentration in the distribution system, measured as total chlorine, combined chlorine, or chlorine dioxide as specified in 179 NAC 13-007.01B and 13-007.02F must be detectable, as defined in Attachment 1 which is hereby incorporated by reference, in at least 95% of the samples each month for any two consecutive months that the system serves water to the public. Thus, the value "V" in the following formula cannot exceed 5% in one month for any two consecutive months. Click here to view
Where:
a = number of instances where residual disinfectant concentration is measured;
b = number of instances where the residual disinfectant concentration is not measured, but heterotrophic bacteria plate count (HPC) is measured;
c = number of instances where the residual disinfectant concentration is measured but not detected and no HPC is measured;
d = number of instances where the residual disinfectant concentration is measured but not detected and where the HPC is greater than 500 ml;
e = number of instances where the residual disinfectant concentration is not measured and HPC is greater than 500 per ml; and
V = percent of samples with undetectable residual disinfectant concentration.
13-005.01D2 If the Director determines, based on site-specific considerations, that a system does not have the means for having a sample transported and analyzed for heterotrophic plate count (HPC) by the Department Laboratory or an approved laboratory under the requisite time and temperature conditions required of the laboratory and that the system is providing adequate disinfection in the distribution system, the requirements of 179 NAC 13-005.01D1 do not apply to that system.005.02 Disinfection Requirements for Public Water Systems Which Provide Filtration: Each public water system that provides filtration treatment must provide disinfection treatment as follows:
13-005.02A The disinfection treatment must be sufficient to ensure that the total treatment processes of that system achieve at least 99.9% (3-log) inactivation and/or removal of Giardia lamblia cysts and at least 99.99% (4-log) inactivation and/or removal of viruses, as determined by the Director.13-005.02B The residual disinfectant concentration in the water entering the distribution system, measured as specified in 179 NAC 13-007.01B and 13-007.03B cannot be less than 0.2 mg per liter for more than four hours.13-005.02C The residual disinfectant concentration in the distribution system, measured as total chlorine, combined chlorine, or chlorine dioxide, as specified in 179 NAC 13-007.01B and 13-007.03B must be detectable, as defined in Attachment 1 in at least 95% of the samples each month, for any two consecutive months that the system serves water to the public. Thus, the value "V" in the following formula cannot exceed 5% in one month, for any two consecutive months. Click here to view
Where:
a = number of instances where the residual disinfectant concentration is measured;
b = number of instances where the residual disinfectant concentration is not measured but heterotrophic bacteria plate count (HPC) is measured;
c = number of instances where the residual disinfectant concentration is measured but not detected and no HPC is measured;
d = number of instances where no residual disinfectant concentration is detected and where the HPC is greater than 500 per ml;
e = number of instances where the residual disinfectant concentration is not measured and HPC is greater than 500 per ml; and
V = percent of samples with undetectable residual disinfectant concentration.
If the Director determines, based on site-specific considerations, that a system has no means for having a sample transported and analyzed for HPC by the Department Laboratory or an approved laboratory under the requisite time and temperature conditions required of the laboratory and that the system is providing adequate disinfection in the distribution system, the requirements of 179 NAC 13-005.02C do not apply.
179 Neb. Admin. Code, ch. 13, § 005
Amended effective 3/22/2016.