Enter your ZIP code. We pull regional water hardness data and tell you exactly what you're dealing with — and whether you can keep cleaning with tap water or need to switch to distilled.
US ZIP codes only. For the 271 covered cities: the utility's own published figure, as on the national rankings. Elsewhere: a planning estimate, labelled as one.
Tap is workable for most surfaces, but on dark or low-angle glass you will start to see faint mineral haze after the second or third wash. Switch to distilled for the rinse step on anything that catches direct light.