Ohio Administrative Code › Title 3745 - Ohio Environmental Protection Agency › Chapter 3745-81 - Primary Drinking Water Rules › Section 3745-81-72 - Disinfection of water from surface water sources

Current through all regulations passed and filed through July 1, 2024
"Disinfection practice" means the application of a disinfectant
				to the treatment flow for the purpose of meeting CT requirements of this rule.
				Significant changes to disinfection practice include any change which will
				affect the ability of a system to meet the CT requirements of this rule.
(A) A public water system that uses a surface
			 water source, in whole or in part, shall provide the disinfection treatment
			 specified in paragraph (B) of this rule. Failure to meet any requirement of
			 this rule, excluding paragraph (E) of this rule, is a treatment technique
			 violation for which public notification is required under rule
			 3745-81-32 of
			 the Administrative Code. Failure to meet any requirement of paragraph (E) of
			 this rule is a monitoring violation for which public notification is required
			 under rule
			 3745-81-32 of
			 the Administrative Code. A public water system that uses a surface water
			 source, in whole or in part, and does not already provide filtration treatment
			 shall comply with any interim disinfection requirements established by the
			 director before filtration is installed.
(B) Each public water system that uses a
			 surface water source, in whole or in part, shall provide disinfection treatment
			 of the water as follows:
(1) The disinfection
			 treatment shall be considered sufficient if the total treatment processes of
			 that public water system would consistently and reliably achieve at least 99.9
			 per cent (3 log) inactivation and/or removal of Giardia lamblia cysts and at
			 least 99.99 per cent (4 log) inactivation and/or removal of viruses, as
			 determined from table A, and tables B-1 to B-13 of this rule or tables under
			 paragraph (N) of rule
			 3745-81-68
			 of the Administrative Code. The inactivation by disinfection is calculated from
			 the actual CT divided by the required CT during the peak hourly flow of each
			 day that the public water system is in operation.
(2) Table A of this rule lists: the minimum
			 requirement for inactivation and/or removal of Cryptosporidium, Giardia lamblia
			 and viruses; the extent to which a properly operated conventional filtration
			 treatment, direct filtration (once demonstrated in
			 accordance with rule
			 3745-81-73
			 of the Administrative Code), and slow sand filtration are considered
			 sufficient to remove Cryptosporidium, Giardia lamblia, and viruses; and the
			 minimum disinfection needed to complete the required minimum inactivation
			 and/or removal of Cryptosporidium, Giardia lamblia and viruses. Table A
			 specifies the additional minimum log inactivation of Giardia lamblia and
			 viruses by disinfection if filtration is properly operated and the turbidity
			 treatment technique requirements of rule
			 3745-81-73
			 of the Administrative Code are satisfied. The filtration and disinfection
			 treatment shall include disinfection that consistently and reliably achieves at
			 least the minimum log inactivation by disinfection of Giardia lamblia and
			 viruses as specified in table A.
(3) The residual disinfectant concentration
			 in the water entering the distribution system shall not be less than 0.2
			 milligram per liter free chlorine or one milligram per liter combined chlorine
			 for more than four consecutive hours.
(4) The residual disinfectant concentration
			 in the distribution system shall not be less than 0.2 milligram per liter free
			 chlorine or one milligram per liter combined chlorine in more than five per
			 cent of the samples each month for any two consecutive months that the public
			 water system serves water to the public.