Section 11-20-5 - Maximum contaminant levels for turbidity(a) The MCLs for turbidity apply to all public water systems using surface water sources in whole or in part.(b) The requirements in this subsection apply to filtered surface water systems until June 29, 1993. The requirements in this subsection apply to unfiltered systems until June 29, 1993, or until filtration is installed, whichever is later. The director shall determine, in writing pursuant to 42 U.S.C. § 300g-1(b)(7)(C)(iii), which systems must install filtration. The MCLs measured at a representative entry point(s) to the distribution system, are: (1) One turbidity unit, as determined by a monthly average pursuant to section 11-20-10 except that five or fewer turbidity units may be allowed if the supplier of water can demonstrate to the director that the higher turbidity does not do any of the following: (A) Interfere with disinfection;(B) Prevent maintenance of an effective disinfectant agent throughout the distribution system; or(C) Interfere with microbiological determinations.(2) Five turbidity units based on an average for two consecutive days pursuant to section 11-20-10.(c) The MCL for filtered water turbidity levels, after June 29, 1993, shall be less than or equal to the applicable value in this subsection in ninety-five per cent of the measurements taken every month, and shall not exceed 5 nephelometric turbidity units or NTU at any time for the following filter units: (1) Conventional treatment, direct filtration, and other filtration technologies, 0.5 nephelometric turbidity units or NTU; and(2) Slow sand, and diatomaceous earth, 1.0 nephelometric turbidity units or NTU.(Eff 12/26/81; comp 3/7/92; am and comp 1/2/93; am and comp 12/15/94; am and comp 10/13/97; comp 9/7/99; comp 11/30/02; comp 12/16/05; comp 11/28/11; comp MAY 02 2014 ] (Auth: HRS §§ 340E-2, 340E-9) (Imp: HRS §§ 340E-2, 340E-9; 42 U.S.C. §§ 300g-1, 300g-2; 40 C.F.R. Parts 141, 142, § 141.13, § 142.10 )