Water System Adequacy
New or expanding Group B water systems must be approved by the state or local health jurisdiction before they serve water to consumers.
Some Group B water systems were constructed years ago without any approval. Obtaining approval now, under the new Group B water system regulations (Chapter 246-291 WAC) may not be possible.
Homeowners or prospective home buyers may need to show proof of water system adequacy to meet local permitting or lending requirements. The Group B rule provides a pathway to demonstrate adequacy, even if the existing system was never approved.
The Group B rule sets minimum requirements for local permitting authorities or lending institutions to determine adequacy for existing Group B systems. Each local permitting authority or lending institution may create additional requirements.
The rule defines a Group B water system constructed before January 1, 2014 as adequate for existing connections and existing uses if:
- Its source meets well construction standards (chapter 173-160 WAC).
- The Department of Health or local health jurisdiction conducts a well site inspection and finds no source of contamination that would create public health risk inside the sanitary control area surrounding the well.
- The well meets all health-based water quality standards.
- The water system provides pressure of at least 20 pounds per square inch to each consumer during periods of peak water demand.
An expanding water system is one that is intended to serve additional connections or serve new uses within existing connections. Expanding systems must meet all requirements for approval under the Group B rule. This includes submitting a complete water system design workbook (Word) to the department or local health jurisdiction. Refer to the Group B Water System Design Guidelines (PDF) for assistance.