Rule 3745-81-71 | General requirements for filtration and disinfection of surface water sources.
(A) Rules 3745-81-71 to 3745-81-75 of the Administrative Code are derived from national primary drinking water regulations. The treatment technique requirements of this rule are established in lieu of maximum contaminant levels for the following contaminants: Cryptosporidium, Giardia lamblia, viruses, heterotrophic plate count bacteria, Legionella, and turbidity. Each public water system using a surface water source, in whole or in part, shall provide treatment of that source water which complies with the treatment technique requirements of this rule. The treatment technique requirements consist of installing and properly operating water treatment processes which consistently and reliably achieve the following:
(1) At least 99.9 per cent (3 log) removal and/or inactivation of Giardia lamblia cysts between a point where the raw water is not subject to recontamination by surface water runoff and a later point before or at the first customer.
(2) At least 99.99 per cent (4 log) removal and/or inactivation of viruses between a point where the raw water is not subject to recontamination by surface water runoff and a later point before or at the first customer.
(3) At least 99.0 per cent (2 log) removal of Cryptosporidium between a point where the raw water is not subject to recontamination by surface water runoff and a later point before or at the first customer.
(B) A public water system using a surface water source, in whole or in part, shall be in compliance with paragraph (A) of this rule if the public water system meets the filtration requirements of rule 3745-81-73 of the Administrative Code and the disinfection requirements of rule 3745-81-72 of the Administrative Code.
(C) "Uncovered finished water storage facility" means a tank, reservoir, or other facility used to store water that will undergo no further treatment except residual disinfection and is open to the atmosphere. Systems are not permitted to begin construction of uncovered finished water storage facilities. Failure to comply with this requirement is a treatment technique violation.
Last updated August 7, 2025 at 8:32 AM
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