Window Washing Guide
§ THE TOOLS  ·  02 / 09  ·  GEO-AWARE

Hard Water Severity Scorer.

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. Sources: USGS Water Hardness Survey 2023, EPA municipal CCR data.

Result prefilled from ZIP 57701
◆ DIAGNOSIS · ZIP 57701
YOUR REGION
Rapid City, SD
UTILITY-LEVEL DATA
124
MG/L CACO₃  ·  8.2 GPG
CLASSIFICATION
Hard
SOFT
0–60
MODERATE
61–120
HARD
121–180
VERY HARD
181–250
EXTREMELY HARD
251+
⚡ THE WORKING ANSWER

Distilled rinse, every time.

You are in the band where tap-water cleaning leaves a visible film within minutes of drying. Wash with tap (the surfactant holds the minerals in suspension), but rinse with distilled. This is the single change that fixes 90% of "I cleaned it and it still looks bad" complaints in your region.

№ 01   Wash water
Tap with soap is fine.
№ 02   Rinse water
Distilled, every clean.
№ 03   Soap ratio
One drop Dawn per quart. Do not increase to compensate.
№ 04   Frequency
Monthly on south- and west-facing glass.
◆ Two gallons distilled per cleaning session for an average home.