1. (1) Part 6 of chapter 246-290 WAC establishes filtration and disinfection as treatment technique requirements for water systems using surface or GWI sources. The Part 6 treatment technique requirements are established in lieu of maximum contaminant levels (MCLs) for the following contaminants:

   1. (a) Giardia lamblia;
   2. (b) Viruses;
   3. (c) Heterotrophic plate count bacteria;
   4. (d) Legionella;
   5. (e) Cryptosporidium; and
   6. (f) Turbidity.
2. (2) For water systems using unfiltered surface sources, in whole or part, and that have been required to install, but have yet to complete the installation and operation of, filtration facilities, the turbidity levels at entry points to distribution and sampling/analytical requirements shall be under 40 C.F.R. 141.13 and 40 C.F.R. 141.22, respectively.

[Statutory Authority: RCW 70.119A.180 and 43.20.050. WSR 08-03-061, § 246-290-601, filed 1/14/08, effective 2/14/08. Statutory Authority: RCW 43.20.050 and 70.119A.080. WSR 04-04-056, § 246-290-601, filed 1/30/04, effective 3/1/04. Statutory Authority: RCW 43.20.050 (2) and (3) and 70.119A.080. WSR 03-08-037, § 246-290-601, filed 3/27/03, effective 4/27/03. Statutory Authority: RCW 43.02.050 [43.20.050]. WSR 99-07-021, § 246-290-601, filed 3/9/99, effective 4/9/99. Statutory Authority: RCW 43.20.050. WSR 93-08-011 (Order 352B), § 246-290-601, filed 3/25/93, effective 4/25/93.]