1. (a) A public water system shall determine whether a coliform treatment technique trigger has been exceeded for each month in which it is required to monitor for total coliforms. Results of all samples collected in a calendar month pursuant to Sections 64423, 64424, and 64425 that are not invalidated by the State Board or the laboratory shall be included in determining if a coliform treatment technique trigger has been exceeded. Special purpose samples such as those listed in Section 64421(b) and special purpose samples collected by a public water system during special investigations shall not be used to determine if a coliform treatment technique trigger has been exceeded.

2. (b) A public water system exceeds a Level 1 treatment technique trigger if any of the following occurs:

   1. (1) For a system taking 40 or more samples per month, the system exceeds 5.0% total coliform-positive samples for the month;
   2. (2) For a system taking fewer than 40 samples per month, the system has two or more total coliform-positive samples in the same month; or
   3. (3) The system fails to take every required repeat samples after any single total coliform-positive sample.

3. (c) A public water system exceeds a Level 2 treatment technique trigger if either of the following occurs:

   1. (1) The system has an E. coli MCL violation; or
   2. (2) The system has a second Level 1 treatment technique trigger, within a rolling 12-month period, unless the State Board has determined a likely reason that the samples that caused the first Level 1 treatment technique trigger were total coliform-positive and has established that the system has corrected the problem.

Note: Authority cited: Sections 116271 and 116375, Health and Safety Code. Reference: Section 116375, Health and Safety Code.

History

1. New section filed 5-28-2021; operative 7-1-2021 (Register 2021, No. 22).