<p>In Washington, mains water is delivered by local public water systems, regulated by the Washington State Dept. of Health, Office of Drinking Water under the US EPA Safe Drinking Water Act. Typical hardness: Mostly soft (Seattle well under 30 ppm), harder in some groundwater areas. For a specific ZIP, see the EWG Tap Water Database.</p>
Sources: Washington State Dept. of Health, Office of Drinking Water, EWG Tap Water Database