Rapid City, SD Water Quality (ZIP 57703)

Quick Answers

Is ZIP 57703 tap water safe to drink? PFAS compounds have been detected in 57703's water at an average of 4.44 ppt across 2 compounds. A certified pitcher filter or reverse osmosis system is recommended, especially for sensitive populations.

What filter should I use in 57703? A reverse osmosis system (NSF/ANSI 58) removes 90%+ of PFAS, lead, and arsenic. For smaller households, a pitcher certified to NSF-53 for PFAS (ZeroWater, PUR PLUS) works. Standard Brita cartridges are not certified for PFAS.

ZIP 57703 Water Quality Summary

EPA testing has detected PFAS "forever chemicals" in the water system serving ZIP 57703 (Rapid City, SD). Monitoring found a peak of 5.8 ppt across 1 system, averaging 4.44 ppt over 2 detected compounds. These levels come from individual EPA UCMR 5 water samples (2023-2025). The EPA's 4 ppt limit for PFOA and PFOS is enforced on a running annual average, so a sample above it shows real exposure but is not by itself a violation.

Contamination Level: LOW – Low contamination – PFAS detected but at lower levels; monitoring continues.

Top Detected Compounds in ZIP 57703

• PFHXS: 5.8 ppt
• PFOS: 5.7 ppt (exceeds the EPA 4 ppt limit)

Lead in ZIP 57703 Water

EPA Lead and Copper Rule testing recorded 6 lead samples for the system serving 57703, with a 90th-percentile high of 0.004 mg/L (within the EPA 0.015 mg/L action level). There is no safe level of lead for children; homes built before 1986 should use a certified NSF/ANSI 53 lead filter.

EPA Violations Affecting ZIP 57703

The water system serving 57703 have 9 health-based EPA Safe Drinking Water Act violations on record, including Gross Alpha (excl. radon & uranium), Combined Radium (226 + 228). A health-based violation means a contaminant exceeded its federal limit or required treatment was not applied.

About the Data

Source: EPA UCMR5 monitoring (2023-2025), Lead and Copper Rule samples, and SDWIS violation records tied to the water system that serves 57703 in Rapid City, SD.

Beyond water: other exposures in Rapid City, SD

Drinking water is one exposure route. These are the other federal datasets that cover ZIP 57703 and Pennington County, SD.

Radon risk in Pennington County, SD

The EPA places Pennington County, SD in Zone 2 - a moderate-risk category, with a predicted average indoor radon level between 2 and 4 pCi/L. Zone maps predict the radon potential of an area from geology and existing indoor readings - they do not describe any individual home. Radon is the leading cause of lung cancer among people who have never smoked, and the only way to know your own level is a test kit.

Lead paint risk in Pennington County, SD

Census figures show 49% of homes in Pennington County, SD were built before 1980, and 9% before 1950. Lead-based paint was banned for residential use in 1978, so older housing stock is the strongest available proxy for lead-paint exposure. This is a statistic about the county's housing, not a test of any particular property - if your home predates 1980, a lead swab test is the way to check.

Air quality in Pennington County, SD

Modelled annual fine-particle pollution (PM2.5) for Pennington County, SD averages 5.8 µg/m³, within the EPA's annual PM2.5 standard of 9 µg/m³. PM2.5 is the pollution fraction small enough to reach deep into the lungs. These are CDC modelled estimates for the county as a whole, not a reading taken at this ZIP code.