Water Quality Report · Updated October 07, 2026
TWIN FALLS CITY OF
TWIN FALLS CITY OF delivers tap water graded D (57/100) by TapWaterSafety.org. The utility serves approximately 56,121 residents in TWIN FALLS, Idaho using groundwater. 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 208-736-1540.
Is TWIN FALLS tap water safe to drink?
TWIN FALLS CITY OF delivers tap water that earns a grade of D (57/100) from TapWaterSafety.org — a below-average rating, with multiple concerns including arsenic significantly above health guideline.
The utility serves 56,121 residents in TWIN FALLS, drawing from groundwater.
Public testing data identifies 15 contaminants in this water above EWG's health-based guidelines, including: Arsenic, Haloacetic acids (HAA9), Total trihalomethanes (TTHMs), Dibromoacetic acid, Dibromochloromethane, Bromodichloromethane, Chromium (hexavalent), Haloacetic acids (HAA5), Bromoform, Nitrate, Nitrate and nitrite, Radium, combined (-226 and -228), Uranium, Chloroform, Vanadium. 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.
EPA compliance record
Official U.S. EPA records for TWIN FALLS CITY OF (system ID ID5420058) for the last 3 years. Checked 2026-10-07.
| Rule | Type | Since | Status |
|---|---|---|---|
| Revised Total Coliform Rule | Missed testing | 02/01/2026 | Open |
| Ground Water Rule | Missed testing or reporting | 02/17/2015 | Open |
| Nitrate Rule | Missed testing or reporting | 01/01/2023 | Open |
| Stage 1 Disinfectants and Disinfection Byproducts Rule | Missed testing or reporting | 02/01/2026 | Open |
| Lead and Copper Rule | Missed testing or reporting | 07/01/2022 | Open |
Source: U.S. EPA Enforcement and Compliance History Online (ECHO), from the Safe Drinking Water Information System. See EPA's full report.
Quick actions for TWIN FALLS residents
Top concerns in this water
Based on the most recent EPA and EWG data, these are the most significant water quality issues for TWIN FALLS CITY OF.
Arsenic significantly above health guideline
Moderate concernArsenic detected at 5.26 ppb, 1315x above the EWG health guideline of 0.004 ppb.
Haloacetic acids (HAA9) significantly above health guideline
Moderate concernHaloacetic acids (HAA9) detected at 15.4 ppb, 256x above the EWG health guideline of 0.06 ppb.
Total trihalomethanes (TTHMs) significantly above health guideline
Moderate concernTotal trihalomethanes (TTHMs) detected at 26.6 ppb, 177x above the EWG health guideline of 0.15 ppb.
Contact TWIN FALLS CITY OF
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 TWIN FALLS
Filters matched to the specific contaminants in this water supply.
Reverse osmosis certified for arsenic (NSF/ANSI 58)
$429-$599Reverse osmosis certified under NSF/ANSI 58 for arsenic is the most reliable home option.
Carbon filter certified for VOCs (NSF/ANSI 53)
$180-$599Activated carbon is effective for disinfection byproducts. Look for NSF/ANSI 53 VOC reduction.
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 57/100 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 |
5.26 ppb | 0.004 | 10.0 | 10 | 10 | 0.004 | — | 1315× over |
| Haloacetic acids (HAA9) Disinfection byproduct |
15.4 ppb | 0.06 | — | — | — | — | — | 256× over |
| Total trihalomethanes (TTHMs) Disinfection byproduct |
26.6 ppb | 0.15 | 80.0 | 100 | — | — | — | 177× over |
| Dibromoacetic acid Disinfection byproduct |
4.05 ppb | 0.03 | — | — | — | — | — | 135× over |
| Dibromochloromethane Disinfection byproduct |
10.5 ppb | 0.1 | — | — | — | — | — | 105× over |
| Bromodichloromethane Disinfection byproduct |
4.85 ppb | 0.06 | — | — | — | — | — | 81× over |
| Chromium (hexavalent) Heavy metal |
0.954 ppb | 0.02 | — | — | — | — | — | 48× over |
| Haloacetic acids (HAA5) Disinfection byproduct |
4.53 ppb | 0.1 | 60.0 | 60 | — | — | — | 45× over |
| Bromoform Disinfection byproduct |
9.17 ppb | 0.5 | — | — | — | — | — | 18× over |
| Nitrate Inorganic |
2.31 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 16× over |
| Nitrate and nitrite Inorganic |
2.28 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 16× over |
| Radium, combined (-226 and -228) Radiological |
0.7 pCi/L | 0.05 | 5.0 | — | — | — | — | 14× over |
| Uranium Radiological |
3.15 pCi/L | 0.43 | 20.0 | 30 | 30 | 0.43 | — | 7.3× over |
| Chloroform Disinfection byproduct |
1.29 ppb | 0.4 | — | — | — | — | — | 3.2× over |
| Vanadium Other |
21.8 ppb | 21.0 | — | — | — | — | — | 1.0× over |
| Molybdenum Other |
2.73 ppb | 40.0 | — | — | — | — | — | Below guideline |
| Chlorate Disinfection byproduct |
9.38 ppb | 210.0 | — | — | — | — | — | Below guideline |
| Strontium Radiological |
0.428 ppb | 1500.0 | — | — | — | — | — | Below guideline |
| Chlorodifluoromethane Other |
0.0435 ppb | — | — | — | — | — | — | 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.
TWIN FALLS CITY OF service area
This water system serves 1 community in Twin Falls County, Idaho. Click any city for its dedicated tap water quality page.
Find the right filter for TWIN FALLS water
Browse filter categories by water-quality concern. Each option below is NSF-certified for the matched contaminant type.