Water Quality Report · Updated May 12, 2026
RAPID CITY
RAPID CITY delivers tap water graded D (64/100) by TapWaterSafety.org. The utility serves approximately 72,009 residents in RAPID CITY, South Dakota using surface water. The most significant water quality concerns are: Arsenic significantly above health guideline; Haloacetic acids (HAA9) significantly above health guideline; Total trihalomethanes (TTHMs) significantly above health guideline. For questions, the utility can be reached at 6053944162.
Is RAPID CITY tap water safe to drink?
RAPID CITY delivers tap water that earns a grade of D (64/100) from TapWaterSafety.org — a below-average rating, with multiple concerns including arsenic significantly above health guideline.
The utility serves 72,009 residents in RAPID CITY, drawing from surface water.
Public testing data identifies 7 contaminants in this water above EWG's health-based guidelines, including: Arsenic, Haloacetic acids (HAA9), Total trihalomethanes (TTHMs), Haloacetic acids (HAA5), Radium, combined (-226 and -228), Nitrate, Chromium (hexavalent). For most residents, a properly certified home filter at the kitchen tap is the most cost-effective way to reduce exposure to whatever's in your water. See our filter recommendations below, matched specifically to this utility's contaminant profile.
Quick actions for RAPID CITY residents
Top concerns in this water
Based on the most recent EPA and EWG data, these are the most significant water quality issues for RAPID CITY.
Arsenic significantly above health guideline
Moderate concernArsenic detected at 2.25 ppb, 563x above the EWG health guideline of 0.004 ppb.
Haloacetic acids (HAA9) significantly above health guideline
Moderate concernHaloacetic acids (HAA9) detected at 6.05 ppb, 101x above the EWG health guideline of 0.06 ppb.
Total trihalomethanes (TTHMs) significantly above health guideline
Moderate concernTotal trihalomethanes (TTHMs) detected at 12.1 ppb, 81x above the EWG health guideline of 0.15 ppb.
Contact RAPID CITY
Reach the utility directly for service issues, water quality concerns, or to request your Consumer Confidence Report.
General Contact
Treatment Plant
Recommended water filters for RAPID CITY
Filters matched to the specific contaminants in this water supply.
Reverse Osmosis
$249-$750Arsenic is most effectively removed by reverse osmosis. Some specialized adsorptive filters also work.
Carbon block (NSF/ANSI 42 + 53)
$40-$750Activated carbon is highly effective for disinfection byproducts like TTHM and HAA5.
Disclosure: TapWaterSafety earns a commission from purchases made through these links. This does not influence our scoring methodology or filter selection.
Score breakdown
This utility's overall score of 64/100 breaks down across five weighted components. Read the full methodology →
Contaminants detected — international standards comparison
Every contaminant detected, compared side-by-side against US EPA legal limits, the EU Drinking Water Directive (2020/2184), WHO Guidelines, and California's Public Health Goal (the strictest US benchmark). Why we show multiple standards →
| Contaminant | Detected | EWG US health-based |
EPA US legal |
EU DWD Europe |
WHO global |
CA PHG strictest US |
Tested sample year |
Status |
|---|---|---|---|---|---|---|---|---|
| Arsenic Heavy metal |
2.25 ppb | 0.004 | 10.0 | 10 | 10 | 0.004 | — | 563× over |
| Haloacetic acids (HAA9) Disinfection byproduct |
6.05 ppb | 0.06 | — | — | — | — | — | 101× over |
| Total trihalomethanes (TTHMs) Disinfection byproduct |
12.1 ppb | 0.15 | 80.0 | 100 | — | — | — | 81× over |
| Haloacetic acids (HAA5) Disinfection byproduct |
2.77 ppb | 0.1 | 60.0 | 60 | — | — | — | 28× over |
| Radium, combined (-226 and -228) Radiological |
0.58 pCi/L | 0.05 | 5.0 | — | — | — | — | 12× over |
| Nitrate Inorganic |
1.14 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 8.1× over |
| Chromium (hexavalent) Heavy metal |
0.132 ppb | 0.02 | — | — | — | — | — | 6.6× over |
| Chlorate Disinfection byproduct |
43.8 ppb | 210.0 | — | — | — | — | — | Below guideline |
| Barium Heavy metal |
101.9 ppb | 700.0 | 2000.0 | — | 1300 | 2000 | — | Below guideline |
| Vanadium Other |
2.24 ppb | 21.0 | — | — | — | — | — | Below guideline |
| Molybdenum Other |
0.441 ppb | 40.0 | — | — | — | — | — | Below guideline |
| Manganese Heavy metal |
0.295 ppb | 100.0 | — | 50 | 80 | — | — | Below guideline |
| Strontium Radiological |
0.301 ppb | 1500.0 | — | — | — | — | — | Below guideline |
| 1-Butanol Other |
0.116 ppb | — | — | — | — | — | — | Below guideline |
| Chlorodifluoromethane Other |
0.005 ppb | — | — | — | — | — | — | Below guideline |
| Fluoride Inorganic |
0.649 ppm | — | 4.0 | 1.5 | 1.5 | — | — | Below guideline |
All values in the unit of the detected level. Red cells indicate the detected level exceeds that standard. Some contaminants have limits in some jurisdictions but not others (shown as —). The "Tested" column shows the year each contaminant sample was collected.
Sources: US EPA, EU Drinking Water Directive 2020/2184, WHO Guidelines (4th ed.), California OEHHA PHGs, EWG Tap Water Database.
RAPID CITY service area
This water system serves 1 community in Pennington County, South Dakota. Click any city for its dedicated tap water quality page.
Find the right filter for RAPID CITY water
Browse filter categories by water-quality concern. Each option below is NSF-certified for the matched contaminant type.