Ohio Administrative Code|Rule 3745-81-73 | Filtration of water from surface water sources.

                                                
A public water system that uses a surface water
		source, in whole or in part, shall provide treatment consisting of both
		disinfection, as specified in paragraph (B) of rule 3745-81-72 of the
		Administrative Code, and filtration treatment which complies with paragraph
		(A), (B), or (C) of this rule. Distinction between surface water sources and
		ground water sources is set forth in rule 3745-81-76 of the Administrative
		Code. Filtration treatment shall consistently and reliably achieve at least
		ninety-nine per cent (2 log) removal of Cryptosporidium. Failure to meet any
		requirement of this rule shall be a treatment technique violation and shall
		require public notification as set forth in rule 3745-81-32 of the
		Administrative Code.
(A) Conventional filtration treatment.
		  All public water systems using conventional filtration treatment to treat
		  surface water shall meet the following:
(1)  Turbidity levels of representative
			 samples of filtered water shall be less than or equal to 0.3 nephelometric
			 turbidity units (NTU) in at least ninety-five per cent of the samples analyzed
			 each month.
(2) The turbidity level of representative
			 samples of a public water system's filtered water shall not exceed one
			 NTU.
(B) Slow sand filtration. Filtration by a
		  public water system filtering surface water by slow sand filtration shall meet
		  the following:
(1) For a public water
			 system using slow sand filtration, the turbidity level of representative
			 samples of filtered water shall be less than or equal to one NTU in at least
			 ninety-five per cent of the samples each month.
(2) The turbidity level
			 of representative samples of a public water system's filtered water shall
			 not exceed five NTU.
(C) Alternative filtration technologies
		  and direct filtration treatment. If a public water system using a surface water
		  source, in whole or in part, can demonstrate to the director, using pilot plant
		  studies or other means, that a filtration technology not listed in paragraph
		  (A) or (B) of this rule, in combination with disinfection treatment that meets
		  the requirements of paragraph (B) of rule 3745-81-72 of the Administrative
		  Code, consistently and reliably achieves ninety-nine per cent (2 log) removal
		  of Cryptosporidium, 99.9 per cent (3 log) removal and/or inactivation of
		  Giardia lamblia cysts and 99.99 per cent (4 log) removal and/or inactivation of
		  viruses, the director may accept this alternative filtration technology for use
		  by the public water system. For a public water system that makes this
		  demonstration, the requirements of paragraph (A) of this rule apply. For a
		  public water system that makes this demonstration, the minimum log removal and
		  inactivation requirements for conventional filtration in table A of rule
		  3745-81-72 of the Administrative Code shall apply. Each membrane filter which
		  has been awarded credit for log removal as described in this paragraph shall
		  undergo direct integrity testing daily to verify the log removal the filter has
		  been credited to achieve. The direct integrity testing requirements in
		  paragraph (K)(3) of rule 3745-81-68 of the Administrative Code shall apply. In
		  addition, continuous filtrate turbidity monitoring shall be performed on each
		  membrane filter. If the turbidity of a membrane filter exceeds 0.15 NTU in two
		  consecutive readings taken fifteen minutes apart, the system shall conduct a
		  direct integrity test on the membrane filter. A membrane filter shall be
		  removed from service for repairs until the membrane filter can pass a direct
		  integrity test to verify the log removal it has been credited to achieve.
		  Systems shall submit a monthly report including daily direct integrity test
		  results, any turbidity monitoring results which trigger direct integrity
		  testing, and any corrective action taken.