Nevada’s drinking water safety depends heavily on the source. For most residents connected to public utility systems, the water is treated and consistently meets state and federal safety standards. However, regional risks exist due to Nevada’s unique geology, and the safety of water from private wells is the sole responsibility of the homeowner.
Sources of Nevada’s Municipal Water and Regulatory Oversight
Nevada’s major population centers rely on a mix of surface water and groundwater, each requiring extensive treatment to ensure safety. Southern Nevada, including the greater Las Vegas area, draws nearly 90 percent of its supply from the Colorado River, primarily from Lake Mead, with the remainder sourced from local groundwater aquifers. Northern Nevada communities, such as Reno and Sparks, depend mainly on the Truckee River and regional groundwater supplies.
The regulatory framework that assures the safety of these municipal systems is robust. The Nevada Division of Environmental Protection (NDEP) holds “primacy” for the federal Safe Drinking Water Act (SDWA), meaning it enforces the standards set by the U.S. Environmental Protection Agency (EPA). Public water utilities are licensed and closely monitored by the NDEP’s Bureau of Safe Drinking Water.
This oversight requires public water systems to test frequently for contaminants and treat the water to meet strict Maximum Contaminant Levels (MCLs). Extensive treatment infrastructure removes potential contaminants from the source water, ensuring high quality water is delivered to homes. Public utility systems are thus shielded from the localized, naturally occurring issues that can plague smaller, untreated sources.
Specific Contaminants Affecting Nevada Water Quality
Nevada’s arid geology contributes to specific contaminants in source water, though municipal treatment handles these challenges. Arsenic is a naturally occurring element found in the state’s groundwater, often exceeding federal standards in untreated sources. It is released as water flows through certain mineral deposits in the earth.
Perchlorate is another regional concern, a man-made chemical historically used in solid rocket propellant and manufacturing. Contamination was traced to industrial facilities near Henderson, affecting the Lower Colorado River and Lake Mead. Although the EPA has not issued a national regulation, the NDEP established an action level for the contaminant, and extensive remediation efforts are cleaning up the source groundwater.
Radionuclides, including uranium, are found in Nevada’s groundwater due to the natural breakdown of mineral formations. Prolonged exposure to high levels presents health risks, so municipal treatment processes reduce their presence to safe levels. A less hazardous but noticeable issue is “hard water,” defined by high concentrations of dissolved minerals like calcium and magnesium. This mineral content is common across Nevada and can cause scale buildup in pipes and appliances, but it does not pose a health risk.
Safety Considerations for Private Well Users
Safety considerations are fundamentally different for residents who rely on private wells, as these sources are not regulated by the EPA or the NDEP. The entire responsibility for water quality, including testing and treatment, falls to the well owner. This lack of oversight makes private wells highly susceptible to localized contamination events.
Common risks include bacterial contamination, often indicated by the presence of total coliform, which can enter the well from septic systems or surface runoff. Nitrates are another frequent concern, particularly in agricultural areas where fertilizers or animal waste can leach into the groundwater. Actionable advice for well owners is to test their water at least once a year for total coliform bacteria and nitrates.
A broader range of tests, known as a routine domestic analysis, should be conducted every three to five years. This analysis includes heavy metals like arsenic and uranium. Studies of unregulated domestic wells show that a significant percentage exceed the federal guideline for arsenic, highlighting the need for consistent, owner-initiated testing. Maintaining a wellhead protection area, free of hazardous materials and septic components, is a key step in preventing contamination.