Water quality FAQs

Why does my water have a strong, "foul sewer" odor?

To determine the source of the odor, fill a clean glass with the water in question. Step out of the room with the glass, and smell the water after a few seconds. If no odor remains, the issue is probably located in the drain.

Drain odor, often described as a “sewer smell” is a common problem that may be caused by a buildup of organic matter, bacteria, clogs, or a dry P-trap.

If the odor is at the kitchen sink, run the garbage disposal to clear out any food, then flush the drain with very hot water for 15 seconds. Pour one cup of baking soda in the drain, followed by one cup of white vinegar down the drain. The baking soda and vinegar create a foaming reaction that will help disinfect hard to reach areas of the plumbing where bacteria growth may be causing odors. After 5-10 mins, pour several cups of very hot water down the drain. Wipe under the rubber splash guard of the garbage disposal with white vinegar on a rag to clean odor-causing debris.

The steps above can be used for any drain in the home including the bathroom sink, shower, bathtub, and laundry room sink, and should be performed routinely to prevent future odors.

Why does my water smell like rotten eggs?

Fill a clean glass with the water in question. Step out of the room with the glass, and smell the water after a few seconds. If the rotten egg odor remains, it may be caused by the heat settings on your water heater.

If the thermostat on the water heater is set too high, water can be overheated. This may also back up into the cold water lines, causing warmer water out of the cold tap, and an odor.

If the thermostat on the water heater is set too low, this may encourage growth of thermophilic bacteria, which also can cause an odor. Adjust your water heater to the manufacturer's recommended setting.

Water heaters that have been shut off for long periods of time also can generate a rotten egg odor. Additionally, the metal used for the sacrificial anode in some water heaters can reduce naturally-occurring sulfate in the water to sulfides, causing a rotten egg odor. 

Why does my tap water appear milky or cloudy?

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

Why does my tap water appear brown or yellow?

Check the water coming from the outside hose bib on your home. If water is clear at the hose bib, the cause of discoloration could be due to internal plumbing. If the water from the hose bib is discolored, it could be due to construction work, fire department hydrant exercises, or water main repairs. You can check at the street to see if construction is being done in the area or check the area around fire hydrants to see if they were exercised recently.

Open the cold water tap closest to the water meter and run the water for three to five minutes to see if the water clears up. If the discoloration persists after five minutes, you may have to repeat the flush again (this may take several hours for sediments to settle). Once the water has cleared up, open the remaining cold water taps in the home or building and run the water for another three to five minutes. Flush toilets and run other plumbing fixtures in the home or business.

Remember to clean aerators on faucets periodically to remove any accumulated particles.

Why are there particles in my water?

• White particles: White particles in the water indicate that mineral deposits or scale that have formed on piping or plumbing fixtures have dislodged and come loose.
• Sandy/Rocks: Sediment in the toilet tank comes from mineral build up in our water or materials from the toilet tank settling at the bottom of the tank.
• Black particles: Particles that appear to be black and float to the surface could either be degrading of carbon filter from an at-home water treatment system, water softener resin, or plumbing components (such as rubber gaskets). It is important to replace plumbing parts routinely to avoid degradation.
• Orange/Brown beads ("fish eggs"): Some customers who have water softeners installed may see orange or brown beads in their water, sometimes referred to as “fish eggs.” This occurs due to filter media breakthrough from the water softener. 

For any of these observations, first check the water coming from the outside hose bib. If water is clear at the hose bib, the issue is isolated to the internal plumbing. Contact a professional plumber or the water softener manufacturer for assistance.

What is 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.

What problems does hard water cause?

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.

How can I reduce problems associated with hard water?

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.

Learn more about home treatment systems and/or request a Consumer Reports rating.

What regulations ensure the quality of my tap water?

Congress passed the Safe Drinking Water Act in 1974 to ensure federal law protects the quality of public drinking water.

The Environmental Protection Agency (EPA) sets standards and regulatory limits for the amounts of certain contaminants that may be present in municipal water systems. These contaminant standards are required by the Safe Drinking Water Act and administered through the State of Nevada.

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

Ensuring a reliable, high-quality water supply is our top priority and reflected in annual Water Quality Reports issued by local water providers.

How is my tap water treated and tested?

The Southern Nevada Water Authority uses cutting edge technology to ensure that your water is treated and tested to the utmost standards of safety. The Water Authority is committed to ensuring your water quality, reliability, and security because we know you depend on it every day.

The Water Authority not only tests for more contaminants than required; we test many regulated and unregulated contaminants more frequently than required.

Water quality data is readily available to customers in water quality reports, published annually by your water provider.

Learn more about treatment and testing.

Do you recommend home water quality test kits?

We don't recommend using at-home water quality test kits, as results can be easily misinterpreted. Your water is treated and tested to the utmost standards of safety, but if you would like to have your home's water independently tested, we recommend you request testing through a certified lab.

Should I buy a home water treatment system?

Although home systems can improve the aesthetic qualities of tap water, such as hardness, odor and taste, the municipal water supply is treated to meet all state and federal water quality standards.

Home water treatment systems may be appropriate for individuals with specific medical conditions; those individuals should discuss options with their physicians. It's important you maintain your home water treatment systems, or you can reduce the quality of your drinking water.

Learn more about home treatment systems.

How should I set my home water treatment system?

The hardness of our water is 304 parts per million or 18 grains per gallon, categorized as "very hard."

What is the pink film I see on shower curtains, tubs, toilets, etc.?

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.

How do I get rid of pink film?

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.

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

Are there limits set on fluoride?

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.

Can I reduce the amount of fluoride in my tap water?

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.

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.

Levels of lead in the drinking water supply are 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. Nevada homes built before 1990 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. Levels of copper in the drinking water supply are well below levels that are determined to be a possible health concern.

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.

What is Legionella?

Legionella is a common, naturally occurring bacterium in freshwater and soil ecosystems and is part of a group of water contaminants known as "opportunistic pathogens," as defined by the Centers for Disease Control.

In 2018, Legionella was detected in Southern Nevada's groundwater system, which supplies about 10 percent of Southern Nevada’s total water resources. In response, the Las Vegas Valley Water District (LVVWD) and Southern Nevada Water Authority (SNWA) pioneered and safely implemented treatment processes to address the contaminate and prevent it from compromising drinking water supplies and the community’s water delivery system.

Where is Legionella typically found?

While found in relatively low concentrations in surface water and groundwater systems, Legionella can proliferate in any large plumbing systems such as those found in offices, hospitals, hotels and high rises. Under the right conditions, the bacteria can grow in biofilm found along the interior of water pipes. While there is no risk of infection through drinking, aerosolized through showers, cooling towers, hot tubs, and other water fixtures, Legionella can pose a risk to human health if inhaled, which may cause a severe form of pneumonia known as Legionnaire’s disease or in the milder Pontiac fever.

What conditions favor the growth of Legionella?

When present, Legionella is generally detected in warm water ranging from 77° to 113°F with low residual chlorine levels.

Are public water systems required to monitor for Legionella?

No. While not required to monitor for Legionella in any water source, the SNWA and LVVWD proactively initiated comprehensive studies and analysis of Legionella. These studies emphasize the importance of utility-driven research to protect public health and highlight the need for increased monitoring and updated federal guidance to address Legionella in groundwater supplies throughout the country.

What have the LVVWD and the SNWA found while conducting Legionella studies and testing?

After detecting the presence of Legionella in Southern Nevada’s groundwater system in 2018, the LVVWD and SNWA developed Legionella treatment processes and sampling procedures to protect public health and ensure high-quality water. This includes utilizing cutting-edge ultraviolet water purification technology effective at eliminating Legionella and common chlorination processes to ensure groundwater supplies comply with strict drinking water standards.

What can private well users do to protect their water systems?

Groundwater is under the jurisdiction of the State of Nevada, and private well users should have their wells tested annually to ensure water quality, including testing for Legionella. The LVVWD coordinates with the Nevada Division of Environmental Protection to ensure proper compliance with state and federal water quality standards and protect public health. As a result, Southern Nevada’s municipal drinking water continues to meet or surpass safe drinking water standards.

Are medications and personal care products found in our tap water?

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.

What should I do with old or unused medications?

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.

What is cryptosporidium and what illness can it cause?

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.

How is cryptosporidiosis prevented?

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.

What is giardia and what illness can it cause?

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.

Giardiasis outbreaks occur most frequently in the northeast and northwest areas of the United States, 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.

How is giardiasis prevented?

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.

What is MTBE?

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.

Is MTBE in our water supply?

The Water Authority regularly tests both its groundwater and surface water supplies for MTBE. View water quality reports and summaries for current concentration information. 

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.

What is perchlorate?

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.

Is perchlorate in our water supply?

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. View water quality reports and summaries for current concentration information. 

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.

What are 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.

Why are quagga mussels harmful?

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.

How are quagga mussels monitored?

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.

What are trihalomethanes?

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

How are trihalomethanes prevented?

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.

What are PFAS?

Per- and polyfluoroalkyl substances (PFAS) are manufactured chemicals used in many household products including nonstick cookware, waterproof band-aids, stain repellants and other waterproofing items. They are also used in industrial applications such as in firefighting foams and electronics production. There are thousands of PFAS chemicals, and they persist in the environment.

Two well-known PFAS chemicals are perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). These were phased out of production in the United States and replaced by other PFAS compounds.

Additional information on PFAS from the United States Environmental Protection Agency (EPA) can be found at https://www.epa.gov/pfas.

What is the EPA doing to address PFAS?

The EPA has established regulatory limits for a small number of PFAS compounds, including PFOA and PFOS. The EPA's regulatory limits for PFOA and PFOS individually are 4 parts per trillion (ppt). The EPA also established regulatory limit for a mixture of four other PFAS that includes: GenX, Perfluorononanoic acid (PFNA), Perfluorohexanesulphonic acid (PFHxS), and Perfluorobutanesulfonic acid (PFBS) of 10 ppt. The EPA also set a non-enforceable health-based goal, a Maximum Contaminant Level Goal, at zero.

What has the SNWA been doing to address PFAS compounds?

From 2023 to 2025, the Southern Nevada Water Authority (SNWA) and thousands of other drinking water agencies will monitor for other PFAS compounds as required by EPA's Unregulated Contaminant Monitoring Rule 5.

Water quality sampling and monitoring indicates Southern Nevada's drinking water is below detectable limits for these PFAS compounds.

Although PFAS compounds are a recent topic of discussion in the news, SNWA's research scientists have been studying and monitoring PFAS for more than a decade, far exceeding the testing and analysis conducted by other water agencies or commercial compliance laboratories.

How could I be exposed to PFAS chemicals?

Most of your exposure to PFAS chemicals comes from things other than drinking water. PFAS are manufactured chemicals, and these compounds do not naturally occur. According to the EPA, more than 80 percent of PFAS exposure comes from consumer goods and not drinking water. Many PFAS compounds are still used in manufacturing today.

The EPA established these regulations following years of research about the potential health impacts of PFAS at certain levels and how water utilities can help protect drinking water. The goal is to set the regulation at the lowest possible levels to protect public health, considering feasibility and affordability.

What are microplastics?

Microplastics are an emerging environmental concern that has garnered significant public attention in recent years, but the Southern Nevada Water Authority’s (SNWA) research scientists have been proactively studying the issue – and its impact on drinking water – for more than a decade to protect the Las Vegas Valley’s water supply.

Research has shown that the concentration of measurable microplastics in Lake Mead is extremely low. Concentrations have ranged from 0.0004 to 0.01 particles per liter. To put that into perspective, 100 to 2,500 liters of untreated water from Lake Mead would have to be consumed to ingest a single microplastic particle.

What has the SNWA been doing to address microplastics?

SNWA’s water treatment facilities utilize filtration processes capable of removing particles smaller than a micrometer (or about 1/50th the width of a single human hair), effectively removing microplastics above this threshold. The SNWA also utilizes highly specialized microplastic sampling equipment, and the agency is currently working on additional research efforts with Rutgers University and the Water Research Foundation.

What causes microplastics?

Microplastics enter the environment through many different human uses. Studies have shown that the atmosphere plays a major role in the transportation and prevalence of microplastics, as microplastics have been found in remote lakes that have very little human interaction. The public can help to reduce the spread of microplastics within our local watershed by avoiding the use of common household products, including microbeads used in cosmetics, plastic chopping boards, dishwasher/laundry pods, sponges, kitchen brushes, and nonstick pans.