Office of Drinking Water. The Department of Health (DOH), Office of Drinking Water (ODW) is responsible for ensuring public water systems provide their customers an adequate and safe drinking water supply at all times. When necessary, ODW acts or directs water system owners and operators to resolve known or suspected public health threats. ODW's authority comes from the:

• Federal Safe Drinking Water Act;
• Code of Federal Regulations;
• state laws; and
• (DOH rules.

Federal regulations establish primary drinking water requirements for larger public water systems, known as group A public water systems. The U.S. Environmental Protection Agency delegated primary authority to administer and enforce these regulations to ODW.

ODW also administers state Board of Health (board) and DOH rules that cover the operation of public water systems. ODW has authority to adopt rules necessary to protect public health by ensuring safe and reliable drinking water. The rules set drinking water standards and requirements for monitoring, reporting, and responding to emergencies.

Water System Plans. The board is required to adopt rules for group A public water systems, necessary to assure safe and reliable public drinking water, and to protect public health, including rules relating to public water system planning and emergency response requirements.

A community water system designated as group A—those public water systems serving 15 or more year-round service connections, or 25 or more year-round residents—must submit a water system plan, or plan update, to DOH for approval if it meets certain conditions, such as those systems serving 1000 or more connections, making infrastructure changes, or expanding their service area.

Water system plans must address several elements, including:

• description of the water system;
• basic planning data;
• demand forecasts;
• system analysis;
• water resource analysis; and
• other plans and documents.

Beginning June 30, 2024, DOH must ensure water system plans for group A community public water systems serving 1000 or more connections include a climate resilience element at the time of approval.

DOH must:

• update its water system planning guidebook to assist water systems in implementing the climate resilience element, including guidance on any available technical and financial resources;
• provide technical assistance to public water systems based on their system size, location, and water source, by providing references to existing state or federal risk management, climate resiliency, or emergency management and response tools that may be used to satisfy the climate resilience element; and
• develop grant and loan eligibility criteria and consider applications from water systems that identify climate readiness projects.

Subject to available funding, the University of Washington Climate Impacts Group must assist DOH in developing technical assistance tools. To fulfill the planning requirements of this element, water systems must:

• determine which extreme weather events pose significant challenges to their system and build scenarios to identify potential impacts;
• assess critical assets and the actions necessary to protect the system from the consequences of extreme weather events on system operations; and
• generate reports describing the costs and benefits of the system's risk reduction strategies and capital project needs.

Climate readiness projects, including planning to meet the requirements of the climate resilience element and actions to protect a water system from extreme weather events, including infrastructure and design projects, are eligible for financial assistance under the Water System Acquisition and Rehabilitation Program.