Nebraska Administrative Code › Topic - HEALTH AND HUMAN SERVICES SYSTEM › Title 179 - PUBLIC WATER SYSTEMS › Chapter 13 - SURFACE WATER TREATMENT › Section 179-13-005 - DISINFECTION

Current through June 17, 2024
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.
13-005.01D
Residual Disinfectant
				Concentration
13-005.01D1 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.
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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.