(1) All public water systems shall provide an adequate quantity and quality of water in a reliable manner at all times consistent with the requirements of this chapter.

(2) During normal operating conditions, for both average and peak demand periods, water pressure at the consumer's service meter, or property line if a meter is not used, shall be maintained at the approved design pressure, but in no case be less than 20 psi (140 kPa). Water quality shall be maintained as required in Part 4 and Part 6 of this chapter.

(3) When fire flow is required, 20 psi (140 kPa) at the operating hydrant and at least positive pressure shall be maintained throughout the system under fire flow conditions.

(4) The purveyor shall address abnormal operating conditions, such as those associated with fires, floods, unscheduled power outages, facility failures, and system maintenance, by using measures consistent with applicable regulations and industry standards to ensure the system is constructed, maintained, and operated to protect against the risk of contamination by cross-connections as a result of loss of system pressure.

(5) For operations during abnormal conditions, the purveyor shall establish the level of reliability, in accordance with consumer expectations, to ensure prevention of loss of pressure or prompt restoration of pressure when a loss of pressure has occurred. Consumer expectations may be established by a simple majority of the affected consumers within the system's service area, or within specific, definable pressure zones when different levels of service may be encountered. A simple majority of consumers can be associated with either a vote of the consumers for privately owned and operated systems, or of the system's governing body, such as council, board, or commission, for publicly governed systems. Consumer expectations shall not be used by a purveyor to justify a failure to address routine or repeated loss of pressure within the system, or within specific, definable pressure zones, because of the purveyor's failure to properly construct, maintain, or operate the system. The level of reliability established under this subsection, and measures for achieving such reliability, shall be identified in the operations and maintenance program and incorporated into the water system design, and shall be approved by the department. The level of reliability shall not affect the purveyor's obligations under subsections (1) through (4) of this section.

(6) The purveyor shall implement all appropriate measures necessary to meet the identified level of reliability for normal and abnormal operating conditions. Procedures for system operation during normal and abnormal operating conditions shall be documented in an operations and maintenance and emergency response program in accordance with WAC 246-290-415 and shall be implemented in a timely and reasonable manner.

(7) If a purveyor is unable to satisfactorily address departmental concerns or consumer complaints regarding the level of reliability associated with normal or abnormal operating conditions, the purveyor may be required to prepare a project report pursuant to WAC 246-290-110 that addresses an evaluation of the problem, impacts on affected consumers, and recommended corrective action. Unless the department determines that public health protection requires otherwise, improvements related to abnormal operating conditions described under subsection (5) of this section will be required commensurate with the established level of reliability for abnormal operating conditions.

(8) Restrictions on designed, or historically documented, normal water uses shall not be allowed except under the following conditions:

(a) Whenever there is clear evidence that, unless limitations are imposed, water use at normal levels will lead to a relatively rapid depletion of water source reserves, such as in drought situations or when significant facility failures occur;

(b) Whenever a water system observes that demands for water exceed the available supply, as a result of such events as miscalculated planning, inattentive operation, or unforeseen problems with sources and that limitations would be necessary to insure basic levels of service while additional sources were being sought or developed, or the situation was being otherwise remedied; or

(c) Whenever the water system institutes restrictions as part of a water use efficiency program which has been accepted by the system consumers through appropriate public decision-making processes within existing governance mechanisms, or has been mandated under state regulatory authority.

(9) A purveyor shall provide the department with the current names, addresses, and telephone numbers of the owners, operators, and emergency contact persons for the system, including any changes to this information. The purveyor shall also maintain twenty-four-hour phone availability and shall respond to consumer concerns and service complaints in a timely manner.