Washington Clarifies Water System Classifications to Prevent Overregulation of Small Providers

In a unanimous move by both chambers of the legislature, Washington state has enacted House Bill 1615 to improve the accuracy and consistency of public water system classification. Signed into law on April 16, 2025, the measure corrects long-standing issues in how Group A and Group B water systems are designated—issues that have had significant compliance and cost implications for small water providers across the state.

A Targeted Fix for an Overbroad Rule

Historically, state regulators could classify a water system as Group A—triggering stricter compliance obligations—based on a default population-per-connection estimate, rather than actual user data. This practice, often used in remote or seasonal communities, sometimes led to inaccurate classifications that imposed regulatory burdens on systems serving fewer people than assumed.

HB 1615 eliminates that loophole. Under the new law, agencies can no longer use default population metrics that would cause a system to be classified as Group A when it doesn’t meet the actual usage threshold. Group A systems will now be classified based only on verified criteria:

• 15 or more service connections,
• 25 or more people served per day for 60 or more days annually, or
• 1,000 or more people served for two or more consecutive days.

Why It Matters

This policy correction is not a minor procedural change—it represents a significant shift in how regulatory fairness and public health protection are balanced.

For small utilities, rural communities, and independent water purveyors, the previous classification method often meant grappling with unnecessary infrastructure upgrades, testing protocols, and reporting demands. These requirements are designed for large-scale systems and can strain the financial and operational capacity of smaller providers.

By preventing unwarranted Group A designations, the law helps ensure that regulations match real-world risk and scale, without compromising the quality or safety of drinking water.

Implications for Environmental Governance

The bill also supports greater transparency and accountability in how public water systems are managed. As states navigate the growing complexity of water infrastructure—exacerbated by climate impacts, aging assets, and population shifts—ensuring that classification frameworks are data-driven and equitable is essential.

In addition, HB 1615 allows local governments to establish more stringent requirements for Group B systems, but only if they are at least as rigorous as state standards and do not result in duplicate permitting. This supports local innovation in water safety while maintaining uniformity across jurisdictions.

While specific to Washington, this legislation reflects a broader need for states to reexamine legacy regulations that may no longer reflect current water use patterns or technological realities. As the Safe Drinking Water Act continues to evolve at the federal level, state-level precision in rulemaking will become increasingly critical.