We analyzed tap water quality data for hundreds of cities in Nevada to identify the 25 with the most contaminants exceeding health guidelines. This ranking is based on 2026 data from the EPA and EWG databases.
While all public water systems must meet EPA legal limits, many health experts — including the Environmental Working Group — argue that these legal limits are outdated and don't reflect current scientific understanding of safe exposure levels. The cities below have the widest gap between what's in their water and what's considered safe by modern health standards.
Rankings at a Glance
Sun Valley, Nevada
Sun Valley has 18 contaminants exceeding EWG health guidelines out of 43 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Sun Valley water report →Elko, Nevada
Elko has 18 contaminants exceeding EWG health guidelines out of 41 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Elko water report →Carson City, Nevada
Carson City has 18 contaminants exceeding EWG health guidelines out of 32 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Carson City water report →Reno, Nevada
Reno has 17 contaminants exceeding EWG health guidelines out of 42 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Reno water report →Las Vegas, Nevada
Las Vegas has 17 contaminants exceeding EWG health guidelines out of 32 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Las Vegas water report →Fernley, Nevada
Fernley has 17 contaminants exceeding EWG health guidelines out of 28 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Fernley water report →Dayton, Nevada
Dayton has 16 contaminants exceeding EWG health guidelines out of 29 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Dayton water report →Boulder City, Nevada
Boulder City has 16 contaminants exceeding EWG health guidelines out of 28 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Boulder City water report →Henderson, Nevada
Henderson has 15 contaminants exceeding EWG health guidelines out of 28 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Henderson water report →Nellis AFB, Nevada
Nellis AFB has 15 contaminants exceeding EWG health guidelines out of 25 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Nellis AFB water report →Carlin, Nevada
Carlin has 14 contaminants exceeding EWG health guidelines out of 17 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Carlin water report →Overton, Nevada
Overton has 13 contaminants exceeding EWG health guidelines out of 17 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Overton water report →Graeagle, Nevada
Graeagle has 13 contaminants exceeding EWG health guidelines out of 15 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Graeagle water report →Mesquite, Nevada
Mesquite has 12 contaminants exceeding EWG health guidelines out of 22 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Mesquite water report →Golconda, Nevada
Golconda has 12 contaminants exceeding EWG health guidelines out of 16 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Golconda water report →Glenbrook, Nevada
Glenbrook has 11 contaminants exceeding EWG health guidelines out of 15 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Glenbrook water report →Stateline, Nevada
Stateline has 11 contaminants exceeding EWG health guidelines out of 15 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Stateline water report →Jackpot, Nevada
Jackpot has 11 contaminants exceeding EWG health guidelines out of 13 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Jackpot water report →Winnemucca, Nevada
Winnemucca has 10 contaminants exceeding EWG health guidelines out of 17 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Winnemucca water report →Incline Village, Nevada
Incline Village has 10 contaminants exceeding EWG health guidelines out of 11 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Incline Village water report →Mcgill, Nevada
Mcgill has 10 contaminants exceeding EWG health guidelines out of 10 detected — significantly above the national average. Multiple known carcinogens were found at levels of concern.
See full Mcgill water report →Stagecoach, Nevada
Stagecoach has 9 contaminants exceeding EWG health guidelines out of 17 total detected, placing it among the most concerning water supplies analyzed.
See full Stagecoach water report →Yerington, Nevada
Yerington has 9 contaminants exceeding EWG health guidelines out of 15 total detected, placing it among the most concerning water supplies analyzed.
See full Yerington water report →Silver Springs, Nevada
Silver Springs has 9 contaminants exceeding EWG health guidelines out of 15 total detected, placing it among the most concerning water supplies analyzed.
See full Silver Springs water report →Sparks, Nevada
Sparks has 9 contaminants exceeding EWG health guidelines out of 10 total detected, placing it among the most concerning water supplies analyzed.
See full Sparks water report →What We Found: Key Patterns
The most frequently detected contaminants exceeding health guidelines across these cities are Dibromochloromethane, Total trihalomethanes (TTHMs), Haloacetic acids (HAA5). These appear repeatedly across different water systems and regions.
Water quality varies significantly even within the same state, driven by local geology, agricultural activity, and industrial proximity.
Across all ranked cities, 330 contaminant readings exceed EWG health guidelines, but only 2 exceed EPA legal limits. This gap of 328 highlights how legal standards may not fully protect public health — EPA limits haven't been updated for many contaminants in decades.
Full Rankings Table
| Rank | City | State | Detected | Above Guidelines | Above Legal | People Served |
|---|---|---|---|---|---|---|
| 1 | Sun Valley | NV | 43 | 18 | 0 | 17,000 |
| 2 | Elko | NV | 41 | 18 | 0 | 20,451 |
| 3 | Carson City | NV | 32 | 18 | 0 | 59,000 |
| 4 | Reno | NV | 42 | 17 | 0 | 442,000 |
| 5 | Las Vegas | NV | 32 | 17 | 0 | 1,539,277 |
| 6 | Fernley | NV | 28 | 17 | 1 | 23,064 |
| 7 | Dayton | NV | 29 | 16 | 0 | 15,830 |
| 8 | Boulder City | NV | 28 | 16 | 0 | 15,000 |
| 9 | Henderson | NV | 28 | 15 | 0 | 336,534 |
| 10 | Nellis AFB | NV | 25 | 15 | 0 | 1,002 |
| 11 | Carlin | NV | 17 | 14 | 0 | 0 |
| 12 | Overton | NV | 17 | 13 | 0 | 8,500 |
| 13 | Graeagle | NV | 15 | 13 | 0 | 120 |
| 14 | Mesquite | NV | 22 | 12 | 0 | 26,000 |
| 15 | Golconda | NV | 16 | 12 | 0 | 60 |
| 16 | Glenbrook | NV | 15 | 11 | 0 | 1,000 |
| 17 | Stateline | NV | 15 | 11 | 0 | 0 |
| 18 | Jackpot | NV | 13 | 11 | 0 | 1,240 |
| 19 | Winnemucca | NV | 17 | 10 | 0 | 8,066 |
| 20 | Incline Village | NV | 11 | 10 | 0 | 0 |
| 21 | Mcgill | NV | 10 | 10 | 0 | 1,200 |
| 22 | Stagecoach | NV | 17 | 9 | 1 | 1,628 |
| 23 | Yerington | NV | 15 | 9 | 0 | 340 |
| 24 | Silver Springs | NV | 15 | 9 | 0 | 0 |
| 25 | Sparks | NV | 10 | 9 | 0 | 1,310 |
Frequently Asked Questions
What city has the worst tap water in Nevada?
Based on 2026 data, Sun Valley, NV has the most contaminants exceeding EWG health guidelines among the cities we analyzed.
How are cities ranked in this report?
Cities are ranked by the number of contaminants exceeding EWG health guidelines. These guidelines are typically stricter than EPA legal limits and reflect current scientific research on safe exposure levels.
Is my tap water safe if my city isn't on this list?
Not necessarily. Even cities not on this list may have contaminants of concern. We recommend checking your specific water quality using our free water scan tool.
What's the best water filter for contaminated water?
A reverse osmosis (RO) system is the most effective for removing the widest range of contaminants. For whole-home protection, a combination of RO for drinking water and a whole-home filter for showers and baths is recommended.
Related Reports
Data sources: Environmental Working Group (EWG) Tap Water Database, U.S. EPA Safe Drinking Water Information System (SDWIS)
Last updated: April 2026
Methodology: Contaminant levels are compared against both EPA legal limits (Maximum Contaminant Levels) and EWG health guidelines, which are often stricter and based on the latest scientific research.
