Is Mesa Tap Water Safe to Drink in 2024? (According to Data)

Is the tap water in Mesa safe to drink? Does the City adhere to drinking water standards set by the Environmental Protection Agency? Are there any contaminants of concern that you should be aware of?

You’ll find all the answers to these questions and more in this Mesa drinking water safety and quality guide.

🚰 Can You Drink Mesa Tap Water?

Yes, you can drink the City of Mesa tap water because the water quality is acceptable and safe according to EPA standards (under the Safe Water Act). The majority of public drinking water utilities in the US, including Mesa Water Resources, must comply with EPA regulations – so the water in Mesa is technically safe for human consumption.

However, just because water complies with legal requirements, it doesn’t necessarily mean that it’s safe. There are still a number of nasty-sounding contaminants that exist in trace levels in Mesa drinking water.

The EPA’s guidelines are based on data on the potential health effects of certain drinking water contaminants. After reviewing the data, the EPA produced MCLs – the maximum amount of certain contaminants that it believes can exist in water with no known health effects. However, organizations like the Environmental Working Group (EWG) think that the EPA’s MCLs should be a lot lower.

The EWG has conducted its own research and established a set of more stringent Health Guidelines for hundreds of contaminants, including some not regulated by the EPA. Looking at the EWG Tap Water Database for the City of Mesa, we can see that 11 contaminants exceed the EWG’s Health Guidelines, making the water (according to the EWG) unsafe for drinking.

In short: the EWG believes that the presence of certain contaminants makes Mesa tap water unsafe, but the water is safe according to EPA drinking water regulations.

We should also mention the EPA ECHO database, which dates from April 2019 to June 2022. According to this database, the City of Mesa water utility was found to have 66 violations (none of them health-related) in one category: Monitoring and Reporting. These violations were resolved in July 2020 and no further reporting violations were identified in the most recent 2022 report.

An official report by the City of Mesa notes that the city has a Pipe Inspection and Replacement Program, which monitors lead pipes and replaces them based on “risk-based prioritization.” It’s unclear whether that means that all pipes in Mesa are lead-free, but note that your water may contain lead if your own plumbing system is old and contains lead.

Mesa SDWA Violations Within 10 Years

Data Source: EPA ECHO database

🗺️ Where Does the Tap Water in Mesa Come From?

There are two primary surface water sources that supply Mesa drinking water:

• The Verde and Salt Rivers (the Salt River Project)
• The Colorado River (the Central Arizona project)

Some parts of Mesa are also supplied by one of 17 deep aquifer groundwater wells in the City.

The water delivered to your home depends on where in the City you live. Generally, the Eastern and Southern Zones are supplied by the Colorado River, while the City Zone is supplied by the Salt and Verde rivers, and groundwater is used to supplement the surface water supplies all over the City.

The quality of the water is largely determined by its source. Groundwater can be more easily protected from contamination (such as runoff and air pollution) compared to surface water, which means it tends to be cleaner and naturally filtered from surrounding rocks and soils.

Mesa has a couple of community schemes in place to preserve its water source. For instance, the City has recently invested in the Greenfield Water Reclamation Plant, which sends treated wastewater to local agricultural communities for crop irrigation. Every 1 acre-foot of reclaimed water replaces 8 acre-feet of water in the Colorado River, helping to conserve water and cut costs for both parties.

Like all public water systems, the Mesa Water District tests its water regularly to ensure it adheres to standards set by the Environmental Protection Agency, with more than 30,000 tests conducted every year to monitor water quality in the City.

Water collected at the source is treated at one of several water treatment plants in Mesa:

• The Val Vista Water Treatment Plant
• The Brown Road Water Treatment Plant
• The Signal Butte Water Treatment Plant

Different water treatment plants use different methods of treatment depending on the water source. These treatments include chlorine dioxide and chlorine disinfection, conventional filtration, ballasted flocculation, ozone disinfection, and fluoridation.

Water is then delivered around the City to meet water supply demands. Mesa’s water delivery system is maintained by Mesa Water Resources.

📉 Who Regulates Mesa Drinking Water?

The City of Mesa drinking water is regulated by the Environmental Protection Agency (EPA) and the Department of Water Resources and managed by the Mesa Water District.

Under the Safe Drinking Water Act (SDWA), the EPA has established National Primary Drinking Water Regulations – standards for contaminants that are known to have health risks in drinking water based on existing research.

According to the EPA’s regulations, contaminants like arsenic, chlorine, and radium can only be present in trace amounts in public tap water. Each drinking water contaminant has a Maximum Contaminant Level (MCL) – a maximum concentration at which the contaminant can be present in water. Some contaminants also have a Maximum Contaminant Level Goal (MCLG) – the maximum amount of the contaminant in water with no known health effects.

Public water systems must test their water supplies for these contaminants and provide suitable treatment to reduce contaminants to below the EPA’s MCLs. Ongoing monitoring and testing are essential to ensure that contaminant levels don’t creep up to potentially dangerous concentrations. Mesa conducts tens of thousands of tests per year.

There are also a few contaminants that the EPA classes as Contaminants of Emerging Concern, including pharmaceuticals, for which the EPA has produced Health Advisories. These contaminants aren’t officially regulated and don’t need to be reduced or removed in water – but some water utilities may choose to do so based on evidence of their health effects.

🧪 Mesa Annual Water Quality Report

An annual Water Quality Report (or Consumer Confidence Report) is released every year by the Mesa Water District. The latest Report, documenting test results from January to December 2021, includes the following information:

• The water source
• Testing that was performed
• Which contaminants were found in the water
• How these contaminants compare to EPA enforcement/MCLs

We can see from the Report that Mesa drinking water meets or surpasses all drinking water standards set by the state or federal government. No contaminants were detected above the EPA’s MCLs, meaning that – technically – the water is legally safe to drink.

However, that doesn’t mean that there are no detected contaminants in Mesa tap water, and you might personally be uncomfortable drinking even traces of certain impurities.

For example, 23 PPB (parts per billion) of HAA5, a disinfection byproduct with known health effects including an increased risk of cancer, was detected in the City’s water supply. This is well within the EPA’s MCL for this drinking water contaminant of 60 PPB – but many folks would rather not drink even traces of a carcinogenic chemical.

Some of the contaminants listed that were found below EPA MCLs include:

• Arsenic
• Barium
• Bromate
• Chlorite
• Chromium
• Chlorine
• Chlorine dioxide
• Copper
• Fluoride
• Haloacetic acids (HAA5)
• Lead
• Nitrate
• Gross alpha

The Report also lists other parameters of interest, including hardness, pH, and iron and nickel levels.

Only the contaminants present in the City’s water are listed in the Report, so you won’t find contaminants that weren’t tested for or detected.

Remember that the data featured in any Consumer Confidence Report is accurate to the specific testing year only. The report doesn’t account for fluctuations in contaminant levels or amendments or reevaluations of EPA regulations.

We recommend reading through the most recent Water Quality Report and making a note of the contaminants that you’d like to learn more about. The Mesa Government website also shares Water Quality Reports from the previous 4 years, so you can compare reports to see how the city’s water quality has changed over time.

Term	Description
Period of Compliance	Time period which a violation took place and resolved.
Status	Indication of the most recent compliance status of the violation. Resolved: The system has returned to compliance from the violation Archived: The violation is not yet resolved, but is more than 5 years past its compliance end date. Addressed: The violation is not resolved nor archived, but addressed through formal enforcement. Unaddressed: The violation has not been addressed, resolved, nor archived
Health Based	Whether the violation affects health standards.
Category Code	Category of violation by which it is reported. TT: Treatment Technique Violation MRDL: Maximum Residual Disinfectant Level Other: Other Violation MCL: Maximum Contaminant Level Violation MR: Monitoring and Reporting MON: Monitoring Violation RPT : Reporting Violation
Code	A complete description of violation codes.
Contaminant Code	Represents a contaminant for which the municipal water system has incurred a violation against a primary drinking water regulation.
Rule Code	The National Drinking Water rule. 110: Total Coliform Rule 121: Surface Water Treatment Rule 122: Long Term 1 Enhanced Surface Water Treatment Rule 123: Long Term 2 Enhanced Surface Water Treatment Rule 130: Filter Backwash Rule 140: Ground Water Rule 210: Stage 1 Disinfectants and Disinfection Byproducts Rule 220: Stage 2 Disinfectants and Disinfection Byproducts Rule 230: Total Trihalomethanes 310: Volatile Organic Chemicals 331: Nitrates 332: Arsenic 333: Inorganic Chemicals 320: Synthetic Organic Chemicals 340: Radionuclides 350: Lead and Copper Rule 410: Public Notice Rule 420: Consumer Confidence Rule 430: Miscellaneous 500: Not Regulated 111: Revised Total Coliform Rule
Rule Group Code	Uniquely defines a rule group. 120: Surface Water Treatment Rules 130: Filter Backwash Rule 140: Groundwater Rule 210: Stage 1 Disinfectants and Disinfection Byproducts Rule 220: Stage 2 Disinfectants and Disinfection Byproducts Rule 230: Total Trihalomethanes 310: Volatile Organic Chemicals 320: Synthetic Organic Chemicals 330: Inorganic Chemicals 340: Radionuclides 350: Lead and Copper Rule 400: Other 500: Not Regulated 110: Total Coliform Rules 410: Public Notice Rule 420: Consumer Confidence Rule 430: Miscellaneous
Rule Family Code	Defines the rule family code. 100: Microbials 200: Disinfectants and Disinfection Byproducts Rule 300: Chemicals 400: Other 500: Not Regulated

☣️ Contaminants Found Above Guidelines in Tap Water in Mesa

Mesa doesn’t exceed any Environmental Protection Agency regulations for drinking water quality and safety – no contaminants are found above legal guidelines in the City’s tap water.

So, this section of the guide will look at the contaminants found in concentrations surpassing the Health Guidelines set by the Environmental Working Group (EWG).

Of course, the EWG’s Health Guidelines aren’t legally enforceable, so the fact that several contaminants in Mesa’s water exceed these Guidelines is technically no cause for concern.

However, like the EWG, you might believe that the EPA’s standards are too lenient. If so, you’ll be interested to learn which contaminants are found above EWG Health Guidelines:

1,2-Dibromo-3-chloropropane (DBCP)

1,2-Dibromo-3-chloropropane is a man-made chemical and agricultural pesticide that is toxic to inhale and ingest in large amounts. 0.00391 PPB (parts per billion) of this drinking water contaminant was detected in Mesa drinking water – that’s 2.3x the EWG’s recommended Health Guideline of 0.0017 PPB. However, it’s still well within the EPA’s legal limit of 0.2 PPB.

Arsenic

Arsenic, a carcinogenic heavy metal, is one of the most heavily regulated chemical contaminants in drinking water. 3.91 PPB of arsenic was detected in Mesa water – 977x the EWG’s recommended Health Guideline of 0.004. The EPA’s MCL for this contaminant is 10 PPB.

Haloacetic acids (HAA5)† and Haloacetic acids (HAA9)†

When water is disinfected with chlorine, two types of haloacetic acids – HAA5 and HAA9 – are commonly formed. There are several known health effects of these disinfection byproducts, including an increased risk of bladder and liver cancer. In Mesa water, 15.2 and 31.8 PPB of HAA5 and HAA9 were detected – between 151 and 530x the EWG’s Health Advisories of 0.1 PPB and 0.06 PPB. The EPA has a much higher legal limit of 60 PPB for HAA5, and no legal limit for HAA9.

Hexavalent Chromium

Hexavalent chromium (chromium-6) is a toxic, carcinogenic chemical compound that most water filters struggle to remove. 5.63 PPB of hexavalent chromium was detected in Mesa water – 281x the EWG’s Health Guideline of 0.02 PPB. There is no existing EPA regulation for chromium-6.

Nitrate and Nitrite

Two forms of nitrogen that are particularly common in groundwater supplies are nitrate and nitrite. These contaminants are dangerous in large quantities and may cause headaches, nausea, increased heart rate, and methemoglobinemia (blue baby syndrome) in very young children. In Mesa water, 1.55 PPM (parts per million) of nitrates and nitrites were detected – 11x the EWG’s Health Guideline of 0.14 PPM. The current EPA MCL for these contaminants collectively is 10 PPM.

Radon

Radon is a colorless, odorless radioactive gas that ends up in water due to the natural breakdown of uranium in the ground. Ingesting radon in water may lead to internal organ cancers, such as stomach cancer and lung cancer. 230.50 pCi/L (picoCurie per liter) of radon was detected in Mesa drinking water – 154x the EWG’s recommended Health Guideline of 1.5 pCi/L.

Tetrachloroethylene (perchloroethylene)

Tetrachloroethylene is a manufactured chemical (classed as a volatile organic compound or VOC) that may cause liver damage or cancer if exposure to high quantities occurs. 0.130 PPB of tetrachloroethylene was detected in Mesa tap water – 2.2x the EWG’s Health Guideline of 0.06 PPB. The official legal limit for this contaminant is 5 PPB.

Total trihalomethanes (TTHMs)†

Another disinfection byproduct commonly found in chlorinated city water supplies is trihalomethanes (TTHMs). Elevated levels of TTHMs may cause reproductive effects and cancer. 45.1 PPB of TTHMs were detected – 301x the EWG’s recommended Health Guideline of 0.15 PPB. The EPA’s MCL for TTHMs is 80 PPB.

We can see from the EWG database for Mesa that disinfection byproducts are the most commonly occurring contaminants in the City’s tap water. This is the case in most municipalities across the country because chlorine disinfection is so prevalent. It doesn’t help that the EPA doesn’t yet regulate many of these contaminants, so local authorities aren’t legally required to manage or reduce them.

🧫 Main Contaminants Found in Mesa Tap Water

Now we know which contaminants are the most predominant in Mesa’s drinking water – what about the rest?

Here, we’ve shared the contaminants that exist in the City’s water in very low levels (acceptable according to both the EPA regulations and EWG guidelines):

• 1,4-Dioxane – A volatile organic compound (VOC) and synthetic industrial chemical that may cause kidney and liver toxicity, respiratory problems, lung cancer, and other health issues when ingested in excess.
• Antimony – A metal that’s naturally found in low levels in water; may cause nausea, vomiting, and diarrhea if ingested in very high concentrations.
• Barium – Another naturally occurring metal that dissolves in water as it seeps through barium-containing rocks; may cause diarrhea, abdominal cramps, nausea, vomiting, muscle weakness, and high or low blood pressure if large amounts are consumed.
• Cobalt – A natural element found in rocks, soils, water, animals, and plants; the level of cobalt naturally found in the environment isn’t known to be harmful to the human body.
• Disinfection byproducts – Including bromochloromethane, chlorate, chlorodifluoromethane, and trichloroethylene; have numerous known negative health effects including an increased risk of kidney and liver cancers, hormone disruption, and decreased nervous system activity in high doses.
• Fluoride – A mineral found naturally in the environment that is also produced synthetically and added to water supplies due to its dental health benefits; may cause dental fluoridation (discoloration of the tooth enamel) and skeletal fluorosis (caused by the accumulation of fluoride in the bones) if consumed in excess.
• Germanium – A chemical element that’s found in foods and water; high doses of this drinking water contaminant could damage the kidneys, leading to kidney failure and even death.
• Manganese – A mineral best known for its scale forming abilities in water; doesn’t cause health issues but is associated with hard water effects like mineral deposits, poor lather with soap, and skin and hair irritation.
• Radium – One of the most common radiological contaminants that’s naturally present in soils and rocks; may cause anemia, cataracts, and an increased risk of bone cancer or lung cancer if long-term over-exposure occurs.
• Selenium – A non-metal elementthat enters water through discharge from refineries and mines, agricultural runoff and natural occurrences; may cause hair and fingernail loss, circulation problems, and numbness in fingers and toes if high concentrations are consumed.
• Strontium – A heavy metal that dissolves into natural water sources from rocks, and human activities like manufacturing operations and mining; low levels shouldn’t affect health but can be cancer-causing if consumed in excess.
• Total chromium – Refers to a combination of both trivalent and hexavalent chromium (chromium-3 and chromium-6); chromium-6 is the most harmful form of chromium and which may cause liver damage and cancer if large amounts are ingested.
• Vanadium – Another naturally occurring metal that usually gets into water due to fossil fuel deposits or soil erosion; no known health effects when consumed in low levels in water.

⛲ Mesa Drinking Water in Public Places

The tap water supplied to homes and businesses in Mesa is safe to drink – and that includes the water in public places like bars, hotels, and restaurants.

There is no law that requires restaurants, bars, or any other public place to provide free tap water to customers. However, most restaurants in Mesa should offer free drinking water as a courtesy. In some high-class restaurants, you may only be provided with tap water for free alongside a purchase of another drink.

Likewise, hotels should provide free drinking water to all guest rooms with a bathroom. However, not everyone feels comfortable drinking bathroom sink water, and in some cases (such as if lead or other metals are used in the bathroom plumbing), the water may be unsafe to drink. If you’re concerned, you should be able to ask for tap water at the hotel bar.

If you don’t want to drink the public water in Mesa or you’re concerned about the water quality, you can buy popular bottled water brands like Smartwater and Aquafina from most grocery stores in the City.

💬 Frequently Asked Questions

Where does Mesa get its water?

Mesa gets its water from numerous surface water and groundwater sources, including the Colorado River (which supplies the Southern and Eastern Zones), the Verde and Salt Rivers (which supply water to the City Zone), and groundwater supplies (which supply all zones). You can view a map to see where your water is sourced depending on where in the City you live.

Is Mesa water hard or soft?

The water in Mesa is considered hard or very hard, with an average hardness of 12 to 22 GPG (grains per gallon). The exact water hardness depends on the water source. Signs of hard water at home include white, chalky mineral deposits around your faucets and fixtures, poor lathering with soap, and soap scum on your skin and hair.

Is Mesa AZ water fluoridated?

Yes, the City of Mesa fluoridates its water after the Mesa City Council voted to commence community water fluoridation in September 1999. Mesa’s drinking water is already naturally fluoridated, containing around 0.4 PPM (parts per million) of this mineral – but synthetic fluoride is also added to the water to bring the levels up to around 0.7 PPM. Fluoride has several known dental health benefits, but some people are concerned about the potential health effects of ingesting high concentrations of this mineral.

Is the tap water in Mesa safe to drink?

Yes, tap water in Mesa is safe to drink because the water’s contaminant levels are lower than the MCLs set by the Environmental Protection Agency. However, you might not want to drink even trace amounts of certain contaminants in Mesa’s water, including arsenic, nitrate, nitrite, chromium-6, and disinfection byproducts. Many at-home water filters can reduce these contaminants in your faucet water.

Does Mesa drinking water have chlorine?

No, Mesa’s drinking water isn’t chlorinated – it’s treated with chloramine, which is slightly different, but has largely the same outcomes. Chloramine is a combination of chlorine and ammonia, and – like chlorine – kills microorganisms and prevents recontamination in the water system. Chloramine is considered a more desirable disinfectant because it lasts longer in water than chlorine and produces fewer disinfection byproducts.