(1) The purveyor shall treat all surface and GWI sources using one of the following filtration technologies unless another technology is acceptable to the department:

(a) Conventional;

(b) Direct;

(c) Diatomaceous earth; or

(d) Slow sand.

(2) Purveyors not using one of the filtration technologies in subsection (1) of this section or not complying with the design criteria specified in WAC 246-290-676 shall submit a project report to the department that demonstrates to the department's satisfaction that the existing water treatment facility can be operated to reliably produce, by June 29, 1993, water meeting the operating and performance requirements of WAC 246-290-654 and 246-290-660, respectively. The project report shall comply with the requirements of WAC 246-290-110.

(3) The purveyor shall make the demonstration required under subsection (2) of this section using the latest twelve months of operating data, results of special studies conducted to test the performance of the water treatment facility under adverse water quality conditions or other means acceptable to the department.

(4) For water treatment facilities currently unable to meet the performance and operation requirements, the project report shall specify the modifications needed to upgrade the facility. Purveyors upgrading existing water treatment facilities shall comply with the design and reliability requirements under WAC 246-290-676 and 246-290-678, respectively.

(5) The purveyor of a new system using a surface or GWI source shall be subject to the:

(a) Design and reliability requirements under WAC 246-290-676 and 246-290-678, respectively; and

(b) Operating criteria for new water treatment facilities under WAC 246-290-654.