Water Hardness in 57702
Rapid City, South Dakota · Pennington County
Dataset updated March 9, 2026Matched to 25 water systemsTap readings can vary by utility zone, treatment, and plumbing. Methodology
How this ZIP reading is built
This ZIP reading is built from 25 matched water systems. When more than one system is matched, the displayed value is weighted toward larger known service populations when that data is available.
Hardness is a mineral-content reading, not a drinking-water safety rating. Use it for scale, appliance, and softener decisions; check your utility report or test your tap before sizing treatment equipment. See how we calculate local readings.
Water Systems Serving 57702
These are the systems matched to this ZIP code. The displayed ZIP value is weighted toward larger known service populations when population data is available.
| Water System | Source | Hardness | Pop. Served |
|---|---|---|---|
| Rapid City SD4600406 | surface water | 150 PPM Moderately HardUSGS estimate: 198 PPM | |
| Box Elder SD4600046 | groundwater | 150 PPM Moderately HardUSGS estimate: 558 PPM | |
| Rapid Valley Sanitary District SD4600274 | surface water | 150 PPM Moderately HardUSGS estimate: 810 PPM | |
| Colonial Pine Hills Sanitary Distric SD4600263 | groundwater | 150 PPM Moderately HardUSGS estimate: 258 PPM | |
| Chapel Lane Water Company SD4600264 | groundwater | 150 PPM Moderately HardUSGS estimate: 577 PPM |
Nearby Zip Codes
What This Means For You
Use this ZIP reading as a local planning estimate, not a final treatment specification. Hardness can vary by utility zone, seasonal blend, private well, and building plumbing. Confirm your tap reading with a utility report or home hardness test before sizing equipment.
Know your water hardness?
If you've tested your water or have your utility's CCR report, share your reading to help us improve accuracy for Rapid City, SD (57702).
Frequently Asked Questions
Is the water hard in Rapid City, SD (57702)?
The average water hardness in 57702 is 150 PPM (8.8 GPG), which is classified as moderately hard.
Do I need a water softener in 57702?
With hardness of 150 PPM, a water softener is worth considering for homes in 57702.
Is hard water in 57702 safe to drink?
Water hardness itself is a mineral-content reading, not a drinking-water safety rating. Calcium and magnesium are naturally occurring minerals, but you should check your utility's Consumer Confidence Report for contaminant and compliance information.
How many water systems serve 57702?
Zip code 57702 in Rapid City, South Dakota is served by 25 water systems.
Learn More About Your Water
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