1. (a) The owner of a PWS shall flush the distribution system:

   1. (1) At least once every 2 years;
   2. (2) More frequently than every 2 years if needed to maintain the cleanliness of the distribution piping; or
   3. (3) Less frequently than 2 years if drought conditions limit production capacity or a waiver is granted by the department pursuant to Env-Dw 202, because asset management or maintenance records show that a frequency of over 2 years satisfies flushing objectives.
2. (b) Flushing shall be done at times of minimum system usage whenever possible.
3. (c) For PWSs serving less than 100 individuals, regardless of the number of customers, the owner shall give written notice at least one week in advance of the intended flushing date by first class mail, email, or hand-delivery to all premises served by the PWS in the area that will be affected by the flushing.

4. (d) For PWSs serving 100 or more individuals, regardless of the number of customers, the owner shall give notice at least one week in advance of the intended flushing date to all premises served by the PWS in the area that will be affected by the flushing by one or more of the following methods, at the election of the PWS owner:

   1. (1) In writing and delivered by first class mail, email, or hand-delivery;
   2. (2) Other electronic means such as reverse 911 telephone service; or
   3. (3) Publishing a copy of the notice in a newspaper of general circulation for the area served by the PWS.
5. (e) If the PWS has a website, the owner shall supplement the notice provided pursuant to (c) or (d) above, by posting a notice on the PWS website at least one week in advance.
6. (f) The flushing shall be continued until the water runs clear, at a flushing flow rate of not less than 3 feet per second.

Source. (See Revision Note at part heading for Env-Dw 504) #10465, eff 12-2-13; ss by #14006, eff 6-25-24