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Facts about our water

The United States Environmental Protection Agency (EPA) identifies contaminants to regulate in drinking water to protect public health. The EPA's Safe Drinking Water Act ensures that the drinking water supplied to the public is safe.

Southern Nevada's municipal water supply meets or surpasses all federal Safe Drinking Water Act standards.

The Southern Nevada Water Authority uses cutting-edge technology to ensure that your water is treated and tested to the utmost standards of safety. We not only test for more contaminants in our water than is required; we proactively test many regulated and unregulated contaminants more frequently and intensively than required.

Federal regulations require Water Authority member agencies to produce annual water quality reports. The reports include a comparison to federal drinking water standards, information about municipal water sources and an overview of treatment processes.

While Southern Nevada’s water supply is well within the standards set by the EPA, we want you to know details about how we protect your water and what we monitor. Information about specific contaminants of interest to Southern Nevada residents is contained in the sections below.

As you’re reading about these topics, it may be helpful to keep the following real-world comparisons in mind:

  • Part per billion: Equivalent to one drop of water in an Olympic-sized swimming pool
  • Part per million: Equivalent to one cup of water in an Olympic-sized swimming pool

Lead and copper

The Water Authority actively monitors for lead and copper in the drinking water supply.

The Environmental Protection Agency has set an "action level" for lead at 15 ppb, meaning that if lead is detected at 15 parts per billion or more in a water supply, action needs to be taken.

In 2020, levels of lead were detected at less than 1 ppb, well below levels that are determined to be a possible health concern.

How does lead get into water?

Lead in drinking water is primarily from materials and components associated with service lines and home plumbing.

The Environmental Protection Agency cites brass or chrome-plated brass faucets and kitchen/bath fixtures with lead solder as the most common problem, as they can allow lead to enter the water, especially hot water. In addition, lead service pipes can sometimes corrode, causing lead to get into the water supply. Homes built before 1986 are more likely to have lead pipes, fixtures and solder.

Southern Nevada's water infrastructure does not employ lead service lines or other lead-based components, and local water providers maintain robust corrosion-control programs developed in coordination with the Nevada Division of Environmental Protection.

How can I minimize the potential of exposure to lead in tap water?

When your faucets have gone unused for several hours, you can minimize the potential for lead exposure by flushing your tap for 30 seconds to 2 minutes before using water for drinking or cooking.

If you are concerned about lead in your drinking water, you may wish to have your water tested by a private laboratory.

Elevated levels of lead can cause serious health problems, especially for pregnant women and young children.

For more information, call the EPA Safe Drinking Water Hotline at 800-426-4791, or read the EPA's information about lead in drinking water.

What about copper?

In addition to being naturally present in the environment, copper can work its way into water from copper pipes in household plumbing. The action level for copper is triggered if the level of copper is more than 1.3 parts per million. In 2020, levels of copper in our water supply were detected at less than 1 ppm.

If water hasn’t been used for more than six hours—overnight, for example—you can clear copper from the tap by letting the cold water faucet run for 30 to 60 seconds.

For more information, call the EPA Safe Drinking Water Hotline at 800-426-4791, or read the EPA's information about copper in drinking water.

Hard water

Water is considered "hard" when it contains a high level of dissolved minerals.

In the Las Vegas Valley, the two nontoxic minerals that cause our hard water are calcium and magnesium. They're carried into Lake Mead from the mineral-dense Colorado River and do not pose a health risk.

The hardness of our water is 267 parts per million or 16 grains per gallon, categorized as "very hard."

Hard water can make it difficult to produce a lather (or suds) while washing.

It also can leave a chalky build-up on fixtures and spots on glassware. These effects are solely aesthetic—they don't affect your health.

There are several ways to reduce problems associated with hard water, including the use of:

  • Dishwasher rinse aids
  • Laundry detergents that contain water-softening agents
  • Bath salts such as Epsom salts
  • Lime- or mineral-dissolving household cleaners
  • Household water softener systems

Deposits on fixtures and countertops can be prevented by wiping surfaces dry. Mineral residue on surfaces only occurs when water is allowed to evaporate.


Why is Southern Nevada's water system fluoridated?

Both the Nevada legislature and Clark County voters have mandated that fluoride be added to Southern Nevada’s water supply through legislation passed in 1999 and 2000.

Fluoride levels considerably lower than limits

Low levels of fluoride, about 0.3 milligrams per liter (mg/L), occur naturally in Southern Nevada's water supply.

Per regulations developed by the Nevada State Health Division and administered by the Nevada Division of Environmental Protection, the Southern Nevada Water Authority adds 0.4 mg/L of fluoride (hydrofluorosilicic acid, or HFS) to bring the level to approximately 0.7 mg/L in the municipal water supply.

These levels are considerably lower than the federal Safe Drinking Water Act limit of 4.0 mg/L and the Nevada secondary standard of 2.0 mg/L.

Some home filtration systems reduce fluoride. To find out if your system does so, you can contact the company from which you purchased the product, or call NSF International at 800-673-6275. NSF is an independent, not-for-profit organization that certifies the performance of home water-treatment systems and devices.

Based upon average monthly water usage, municipal water users in Southern Nevada pay a little over $1 per household to cover annual fluoridation costs.

Cloudy water

Drinking water delivered through the municipal system can sometimes look "milky" or "cloudy." This cloudiness often occurs when air become trapped in the water.

While this may impact the water's appearance, it does not affect the water's safety and will not harm household plumbing systems.

Air can be introduced in many ways, including the groundwater pumping process, water pipeline maintenance or temperature differences when cold groundwater is brought to the warmer surface.

Because water pipelines are pressurized, air remains trapped in the water until you open the faucet and release the pressure—similar to the effect created when you open a bottle of soda. The thousands of tiny air bubbles that form give the water a slightly white appearance.

You might specifically notice a change in your tap water's clarity during the summer months. The tiny air bubbles are caused by the introduction of well water to augment Lake Mead supplies and meet our peak summer demand.

There's an easy way to test whether cloudy water is due to trapped air. Fill a glass with tap water and set it on the counter. Observe the water for a minute or two. As the air dissipates, water should clear up.

Medications and personal care products

Prescription and over-the-counter drugs, and personal care products such as lotions, sunscreens, fragrance and housecleaning products, are increasingly being detected in water bodies all over the world.

These substances are mostly found at extremely low levels, typically single-digit parts per trillion. This is well below drinking water standards, which are typically set in the parts-per-billion range—1,000 times higher.

The fact that a substance is detectable in drinking water does not mean it is harmful to humans. To date, research throughout the world has not demonstrated an impact on human health from the trace amounts of these compounds found in drinking water.

The water community is committed to protecting public health. Water professionals continue to examine the occurrence of these substances in drinking-water supplies and the effectiveness of current treatment techniques on removal, and are paying close attention to health-effects research in this area-- including research being conducted by the Water Authority.

Old or unused medications should never be flushed down the toilet, as this is a way that drugs can enter the water supply. The Southern Nevada Health District suggests these methods for the proper disposal of medications:

  • Dump pills in a sealable bag.
  • Crush the pills with a heavy object.
  • Add an absorbent product to the bag, such as coffee grounds, kitty litter or sawdust.
  • Pour liquid medications into the mix and seal.
  • Discreetly hide in the garbage.

You also can visit the Pain in the Drain website to find a medication drop-off location near you.

Pink film

A pink-colored film or ring frequently seen on shower curtains, tubs, toilets and pet water bowls is typically caused by growth of the airborne bacteria Serratia marcesens.

This harmless nuisance organism reacts with standing water and frequently forms during spring and summer months.

The bacteria cannot survive and is not present in the chlorinated drinking water supply.

The best treatment for this film is to keep bathroom surfaces clean using chlorine bleach on a regular basis.

A small amount of chlorine bleach (three to five tablespoons) added to a normal sized toilet bowl will destroy the bacteria.

Whenever a pink film starts to reappear, repeat the cleaning and disinfection process.


Cryptosporidium is a microscopic organism found in untreated surface water such as rivers, creeks and streams. Since 1994, the Southern Nevada Water Authority has tested regularly for this organism throughout the water treatment and distribution systems.

Cryptosporidiosis, the illness associated with this pathogen, may cause severe diarrhea, which may pose a serious health risk to individuals with severely suppressed immune systems.

One of the most effective safeguards against cryptosporidium is ozonation, a water treatment process which uses ozone to destroy pathogenic microorganisms. Both the Alfred Merritt Smith and the River Mountains water treatment facilities have incorporated this advanced disinfection technology into their treatment processes.

How to prevent cryptosporidiosis:

  • Wash your hands before handling food, after using the toilet, and after changing diapers
  • Do not drink out of streams and other untreated water sources
  • Wash raw fruits and vegetables before eating

For more information see the EPA's information on cryptosporidium for immunocompromised individuals.


Since 1994, the Las Vegas Valley's water supply has been tested regularly for giardia, which is a microscopic organism found in most untreated surface water.

Giardiasis, the illness associated with this pathogen, may cause severe diarrhea, abdominal cramps, malaise and weight loss. Vomiting, chills, headache and fever can occur in more serious cases. Giardiasis may pose a serious health risk to individuals with severely suppressed immune systems.

One of the most effective safeguards against giardiasis is ozonation, a water treatment process which uses ozone to eliminate biological organisms. The Southern Nevada Water Authority's Alfred Merritt Smith and River Mountains water treatment facilities, which treat the majority of our water supply, incorporate ozonation into their treatment processes.

Giardiasis outbreaks occur more frequently in the northeast and northwest, possibly due to extended winter seasons and low surface water temperatures. Most community outbreaks occur in water systems with minimum or inadequate treatment to its surface water source, poor sanitation upstream and beaver colonies (or other ground animals such as the muskrat) located near the water supply intake.


Methyl tertiary butyl ether (MTBE) is a natural gas derivative used as a gasoline additive to help reduce smog. Federal research studies have linked MTBE to tumors in laboratory rats. Concerns about the possibility of MTBE entering drinking water supplies through leaks, spills, etc. led the Environmental Protection Agency to urge states to discontinue use of the chemical.

MTBE not in our water supply

The Water Authority regularly tests both its groundwater and surface water supplies for MTBE. The level of MTBE found in water being provided to municipal water customers in the Las Vegas Valley is less than 1 part per billion.

A study conducted by the U.S. Geologic Survey revealed low levels of MTBE in Southern Nevada's shallow groundwater aquifer, which is not used for drinking water. The shallow system is separated from the deep groundwater aquifer—from which the valley draws about 10 percent of its drinking water—by a thick layer of fine clay that forms a nearly impermeable layer.


Perchlorate is a salt formed by the addition of oxygen molecules to chloride. It is used as an oxidizer in rocket propellants, fireworks and munitions, and also is naturally occurring in some fertilizers.

Although perchlorate is not regulated under the federal Environmental Protection Agency’s (EPA) Safe Drinking Water Act, the EPA has issued a preliminary reference dose equivalent—meaning the maximum acceptable daily amount of this material that should be ingested—of 15 parts per billion (ppb).

Lake Mead, which is the source of approximately 90 percent of Southern Nevada’s drinking water, contains low concentrations of perchlorate. Concentrations in the treated water currently average 0.5 ppb.

The sources of perchlorate in Lake Mead—and downstream in the Colorado River system—are two industrial complexes in the southeast portion of the Las Vegas Valley, where perchlorate was produced for industrial use.

Groundwater contaminated with perchlorate traveled to the Las Vegas Wash through the shallow groundwater system and subsequently entered the lake. Although perchlorate is no longer manufactured in that complex, this substance remains in the area’s surface water.

To capture this water and prevent additional perchlorate from entering the Las Vegas Wash, the Nevada Division of Environmental Protection has overseen the installation of an interception system that uses wells to extract the contaminated water. This system has proven extremely effective, reducing the amount of perchlorate entering the Las Vegas Wash by approximately 90 percent.

Reverse osmosis units are generally effective at reducing perchlorate levels in drinking water to below detection limits. The Southern Nevada Water Authority encourages any customers with concerns about perchlorate-related health effects to consult their physician.

To learn more about perchlorate and our water supply, read the Water Quality Report. For general information about perchlorate, see the EPA's perchlorate fact sheet.

Quagga mussels

Discovered in January 2007 at Lake Mead, non-native quagga mussels have caused quite a stir in Southern Nevada. Similar to its cousin, the zebra mussel, the quagga mussel is described by scientists as one of the most invasive species worldwide and can live at depths of nearly 400 feet.

Sometimes referred to as "biological pollution," species like the quagga mussel can cause irreversible harm to the environment. Quaggas pose a serious threat to the ecosystem as well as the water intake system located at Lake Mead.

Quaggas filter up to a liter of water per day, impacting the food chain of native fish and other aquatic wildlife by decreasing the food supply. They also clog and restrict water flow in pipes of all sizes, requiring costly upkeep and repairs. To make matters worse, they multiply at an alarming rate. A single female quagga can produce more than one million eggs in a spawning season.

Quaggas in Lake Mead

Initially discovered in Boulder Basin in early 2007, the mussels have subsequently been found throughout Lake Mead both as adult mussels and as juveniles.

The Water Authority, in cooperation with the Lake Mead National Recreations Area, UNLV, UNR, and other agencies have developed an Interagency Monitoring Action Plan to coordinate the collection and sharing of quagga mussel data for Lake Mead.

SNWA contributes to this effort through our routine Lake Mead water quality sampling program, the collection of juvenile mussels during our water quality sampling, and the regular inspection of our drinking water intake structures by divers.

Other agency partners provide additional water quality data and juvenile mussel data throughout the lake, information on colonization by adult mussels, evaluations of the impact on other organisms, and assistance in preventing the spread of mussels by boats leaving the lake.

No live adult quaggas have been found at SNWA treatment facilities and improvements are being implemented to prevent the colonization of the intake structures by mussels. These control technologies have been incorporated into the design of the third intake. Veligers (quagga larvae) have been found in the raw water as it comes into the treatment plants, but it should be noted that the Water Authority's water treatment processes destroy all quagga before they can get into the drinking water system.

Trihalomethanes – THMs

Trihalomethanes (THMs) are disinfection byproducts created when chlorine used to disinfect water reacts with naturally-occurring organic and inorganic materials.

The Water Authority takes proactive measures to manage the formation of THMs during the water treatment process.

The Environmental Protection Agency (EPA) has set the maximum level of total THMs in treated water at 80 parts per billion. Southern Nevada's municipal water supply meets that health-based standard.

Although some studies have indicated an association between elevated levels of THMs and adverse health effects among pregnant women, no causal relationship has been established.

The Water Authority advises consumers with concerns related to THMs—particularly pregnant women—to call the EPA's Safe Drinking Water Hotline at 800-426-4791.

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