(1) All public water systems shall submit to a sanitary survey conducted by the department, or the department's designee, based upon the following schedule:

(a) For community water systems, every three years. In accordance with 40 C.F.R. 141.21 (d)(3), community water systems may qualify to be surveyed every five years if the system meets the following criteria:

(i) Provides at least 4-log treatment of viruses (using inactivation, removal, or a department-approved combination of 4-log inactivation and removal) before or at the first customer for all its groundwater sources; or

(ii) Has no total coliform or E. coli MCL violations since the last sanitary survey;

(iii) Has no coliform treatment technique violations for failure to conduct the required assessment or complete corrective actions in response to a treatment technique trigger since the last sanitary survey;

(iv) Has no more than one total coliform monitoring violation since the last sanitary survey; and

(v) Has no unresolved significant deficiencies from the current sanitary survey.

(b) For transient noncommunity and nontransient noncommunity water systems, every five years.

(c) For community water systems that use a surface water or GWI source, every three years. Sanitary surveys may be reduced to every five years upon written approval from the department.

(d) The department may schedule a sanitary survey or increases the frequency of surveys if it determines a public health threat exists or is suspected.

(2) All public water system purveyors shall be responsible for:

(a) Ensuring cooperation in scheduling sanitary surveys with the department, or its designee;

(b) At the department's request, provide any existing information that will enable the department to conduct a sanitary survey;

(c) Ensuring the unrestricted availability of all facilities and records at the time of a sanitary survey or special purpose investigation; and

(d) Taking preventive or corrective action as directed by the department when results of a sanitary survey indicate conditions which are currently or may become a detriment to system operation or public health.

(3) All public water systems that use a surface water or GWI source shall, within forty-five days following receipt of a sanitary survey report that identifies significant deficiencies, identify in writing to the department how the system will correct the deficiencies and propose a schedule to complete the corrections. The department may modify the schedule if necessary to protect the health of water system users.

(4) A groundwater system with significant deficiencies must meet the treatment technique requirements of WAC 246-290-453(1) and the special notification requirements under WAC 246-290-71005 (4) and (5) except where the department determines that the significant deficiency is in a portion of the distribution system that is served solely by surface water or GWI.