Mesa Water Quality at a Glance
multiple serious concerns
Is Mesa Water Safe to Drink?
Meets Legal Standards — But Independent Testing Reveals Significant Concerns — Mesa’s water meets all federal and state legal requirements, but third-party testing shows chromium-6 at 5.63 ppb (281x above health guidelines) and arsenic at 4.35 ppb (1,087x above guidelines). Multiple disinfection byproducts are also present. Mesa’s water comes from the Colorado River via the Central Arizona Project, Salt and Verde Rivers via the Salt River Project, and deep groundwater wells, treated through three facilities. Residents — especially those with children — should strongly consider NSF-certified home filtration for drinking and cooking water. Note: EWG health guidelines are not legal limits.
⚠️ Key Concerns for Mesa Residents in 2026
- Chromium-6 “Erin Brockovich Chemical”: 5.63 ppb detected — among the highest levels in the U.S. (281x above EWG’s health guideline of 0.02 ppb); no federal MCL currently exists for chromium-6 specifically.
- Arsenic Contamination: 4.35 ppb detected (1,087x above health guidelines) — naturally occurring cancer-causing heavy metal from Arizona’s desert geology. Below the EPA’s 10 ppb MCL.
- Disinfection Byproducts: Total trihalomethanes at 42.8 ppb and haloacetic acids at 10.9 ppb — below EPA MCLs but significantly above EWG health guidelines. Check our water alerts page for updates.
- PFAS Regulatory Uncertainty: PFHxS was detected at 0.231 ppt. In May 2025, EPA announced it intends to rescind the MCL for PFHxS — but the 4 ppt MCLs for PFOA and PFOS remain in force, with the compliance deadline extended to 2031.
Read the full report below for detailed analysis, water source information, and actionable recommendations for Mesa residents. You can also check live water quality data or track active boil water notices.
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Mesa – Arizona – Water Quality Report 2026: PFAS Testing, Infrastructure Concerns & Safety across your city
Mesa Water Resources provides comprehensive water and wastewater services to approximately 515,000 residents across Arizona’s third-largest city, spanning over 138 square miles in the east Valley of metropolitan Phoenix. The system encompasses an extensive distribution network, three major water treatment facilities, and over 30 groundwater wells delivering an average of 75 million gallons of drinking water daily to this rapidly growing desert community.
Mesa sources its drinking water from multiple sources including the Colorado River through the Central Arizona Project (CAP), Salt and Verde Rivers through the Salt River Project (SRP), and local groundwater aquifers. Water is treated at three facilities: the Brown Road Water Treatment Plant (72 MGD capacity), Signal Butte Water Treatment Plant (24 MGD capacity), and the jointly-owned Val Vista Water Treatment Plant. While Mesa’s water meets all federal and state legal standards, third-party analysis reveals chromium-6 at 5.63 ppb (281x above health guidelines), arsenic at 4.35 ppb (1,087x above guidelines), and multiple disinfection byproducts — contaminants that sit below legal limits but remain a cause for concern based on current health science. Residents should review our water filter recommendations and check the Arizona state water quality overview for broader context.
Mesa Water Quality: Current Status (2025–2026)
Latest Testing Results
- EPA Compliance Status: For the most recent quarter assessed (April–June 2024), Mesa’s water meets all federal health-based drinking water standards and remains in full compliance with EPA and Arizona Department of Environmental Quality (ADEQ) regulations.
- Third-Party Analysis: EWG testing reveals 10 contaminants exceeding health guidelines, including chromium-6 at 5.63 ppb (281x above health guidelines), arsenic at 4.35 ppb (1,087x above guidelines), and multiple disinfection byproducts. Note: EWG health guidelines are not legal limits and are generally far more conservative than federal MCLs. Residents concerned about these findings should review our filter solutions page.
- Lead and Copper Monitoring: The 90th percentile lead level is 3.7 ppb, which meets EPA’s current action level of 15 ppb. However this exceeds the American Academy of Pediatrics’ recommendation of 1 ppb for children. Mesa completed its service line inventory in October 2024 as required by the EPA Lead and Copper Rule Revisions.
Water Sources
- Central Arizona Project (CAP): Colorado River water provides approximately 55% of Mesa’s supply, delivered through the Eastern Zone distribution system and treated at the Brown Road and Signal Butte facilities.
- Salt River Project (SRP): Salt and Verde River water supplies approximately 26% of Mesa’s water through the City Zone, treated at the Val Vista Water Treatment Plant.
- Groundwater Wells: Over 30 deep aquifer wells provide approximately 19% of supply, offering backup capacity and system redundancy — though naturally occurring arsenic concentrations in Arizona’s desert geology can vary by well location and depth. Monitor real-time system status via our live boil water notice tracker.
Advanced Treatment Technology
- Brown Road Water Treatment Plant: Mesa’s primary facility processes 72 million gallons per day using conventional filtration, fluoridation, and dual disinfection with chlorine dioxide and chlorine for Colorado River water.
- Signal Butte Water Treatment Plant: Newer facility featuring advanced ozone disinfection technology with 24 MGD capacity serving southeast Mesa’s growing population.
- Treatment Limitations: Despite advanced treatment, naturally occurring arsenic and unregulated chromium-6 remain in the finished water supply. Neither contaminant has a specific federal remediation trigger at current detected levels — arsenic at 4.35 ppb is below the 10 ppb EPA MCL, and chromium-6 has no federal MCL.
Infrastructure and the 2026 Regulatory Landscape
- PFAS Compliance Update: In May 2025, EPA confirmed it will retain the 4 ppt MCLs for PFOA and PFOS but extended the compliance deadline to 2031 (from 2029). EPA also announced its intent to rescind the MCLs for PFHxS, PFNA, HFPO-DA, and the Hazard Index — meaning Mesa’s detected PFHxS at 0.231 ppt faces reduced regulatory pressure. ADEQ is monitoring developments and conducting state-level PFAS testing.
- Service Line Assessment: Mesa completed its Lead and Copper Rule Revisions inventory in October 2024 as required by EPA. The city is working with ADEQ on implementation of the Lead and Copper Rule Improvements (LCRI), which Arizona is incorporating into state law in 2025–2026.
- Smart Water Management: Advanced monitoring systems throughout the distribution network enable real-time water quality tracking, leak detection, and pressure management across Mesa’s 138+ square miles.
Customer Protection Initiatives
Mesa Water Resources offers comprehensive customer support including water quality testing assistance and the Utility Customer Assistance Program for qualifying low-income residents. Given the detection of chromium-6, arsenic, and disinfection byproducts above health guidelines, residents are strongly encouraged to consider NSF-certified home filtration. Mesa’s annual Consumer Confidence Reports provide full testing data — but as with all U.S. utilities, meeting federal legal limits does not necessarily mean the water meets the latest health science recommendations. For Arizona-wide water quality context, see our Arizona state water report. Contact Mesa Water Resources at 480-644-2221 for testing information.
Recommendations for Mesa Residents
Request Water Testing
Contact Mesa Water Resources at 480-644-2221 for water quality concerns or testing information. Residents concerned about chromium-6, arsenic, or lead should consider independent testing through certified laboratories for their specific address. Annual Consumer Confidence Reports are available at mesaaz.gov. Stay up to date with our water alert news page.
Maximise Water Conservation
Take advantage of Mesa’s Grass-to-Xeriscape (G2X) programme offering $500 rebates for converting 500+ sq ft of grass to desert landscaping. Combine with the “Trees Are Cool” programme for additional $50–$100 tree planting incentives. Reducing demand helps ease pressure on all three supply sources. Track any drought-related restrictions via our live water tracker.
Install Home Filtration
Given Mesa’s elevated chromium-6 (5.63 ppb), arsenic (4.35 ppb), and disinfection byproducts, residents should strongly consider NSF-certified reverse osmosis or ion exchange filters. Reverse osmosis is the most effective technology for removing both arsenic and chromium-6 from drinking water. See our recommended water filter solutions for certified options.
Join Commercial Conservation Programmes
Businesses and HOAs can apply for Mesa’s Non-Residential Irrigation Equipment Incentives and Commercial Grass-to-Xeriscape rebates. Contact becky.zusy@mesaaz.gov or call 480-644-3058 for details. For statewide water conservation context, see our Arizona water quality report.
Report Issues Promptly
Contact Mesa Utility Customer Service at 480-644-2221 for billing questions, service requests, or water quality concerns. For emergencies, call the 24-hour Utility Control Centre at 480-644-2262 to report leaks, pressure problems, or outages. For real-time boil water alerts, bookmark our live boil water notice tracker.
Frequently Asked Questions
Is Mesa’s tap water safe to drink in 2026?
Mesa’s tap water meets all federal and state drinking water legal standards, but independent testing reveals significant health concerns. The city’s water contains chromium-6 at 5.63 ppb (281x above EWG’s health guideline), arsenic at 4.35 ppb (1,087x above health guidelines), and multiple disinfection byproducts above health benchmarks — though all remain below their respective EPA Maximum Contaminant Levels.
The important distinction here is that legal compliance and health protection are not the same thing. Many federal MCLs have not been updated for decades and were set by balancing health risk against the cost of treatment, not solely on what is safest. For vulnerable groups — children, pregnant women, and immunocompromised individuals — installing an NSF-certified reverse osmosis filter is strongly advisable. Our filter solutions page lists certified options effective against arsenic and chromium-6.
What are Mesa’s current water restrictions?
Mesa operates under year-round conservation measures appropriate for desert living:
Standard Conservation Measures: Mesa encourages responsible water use through education and incentive programmes rather than mandatory restrictions, recognising that desert residents typically practise natural conservation.
Landscape Guidelines: The city promotes desert-adapted landscaping through rebate programmes and provides guidelines for efficient irrigation scheduling based on seasonal weather patterns.
Emergency Response: During severe drought or supply emergencies, Mesa may implement temporary restrictions. Current water supply status and any active measures are available at mesaaz.gov or by calling 480-644-2221. Our water alert news page also covers Arizona-wide drought and supply developments.
Why does my water sometimes have a mineral taste?
Mesa’s desert location and diverse water sources can affect taste and mineral content:
Natural Minerals: Mesa’s water is classified as “very hard” at 12.8 grains per gallon — among the most mineral-laden in Arizona. Groundwater wells draw from deep desert aquifers with naturally high calcium and magnesium content.
Source Water Variations: Colorado River (CAP), Salt/Verde River (SRP), and groundwater sources each have distinct mineral profiles. The blend delivered to your address may shift based on operational needs and seasonal supply conditions.
Treatment Processes: Disinfection chemicals, pH adjustment compounds, and chlorine dioxide can occasionally be detectable, especially during hot desert summers when chemical reactions are more pronounced.
If taste issues persist or worsen, contact Mesa Water Resources at 480-644-2221. Running water briefly after periods of non-use can often improve tap taste. For broader context on Arizona water quality, see our Arizona state water report.
Does Mesa’s water contain lead?
Mesa’s lead monitoring shows the following as of the latest available data:
• Current Levels: The 90th percentile lead level is 3.7 ppb — below EPA’s current action level of 15 ppb, but above the American Academy of Pediatrics’ recommendation of 1 ppb for children
• Service Line Inventory: Mesa completed the EPA-required lead service line inventory in October 2024. ADEQ is in the process of incorporating the updated Lead and Copper Rule Improvements (LCRI) into Arizona state law during 2025–2026, which will set stricter future requirements
• Home Plumbing: Homes built before 1986 may have lead-containing solder or fixtures in internal plumbing; residents in older Mesa neighbourhoods should consider independent lead testing
• Recommended Action: Families with young children should consider NSF-certified point-of-use filtration. See our water filter recommendations for lead-certified options. Visit our national water quality tool to compare Mesa’s figures with other cities.
Quality News About Your Water
Get the comprehensive water quality news coverage you need with our dedicated US Water News Service. From coast to coast, we deliver in-depth reporting and expert analysis on PFAS contamination, EPA regulatory changes, infrastructure developments, and emerging water safety issues affecting communities nationwide. While mainstream media only covers the biggest stories, we provide the detailed, ongoing coverage that helps you understand the full scope of America’s water challenges.
What’s actually in your tap water? Enter your ZIP code for a full breakdown of contaminants detected in your local supply
Drinking water from a well? Check our directory here for more information
Contaminants of Concern
Arsenic
Source: Naturally occurring in desert soils and bedrock throughout Arizona, leaching into groundwater aquifers; concentrations vary by well location and seasonal groundwater levels
Health Effects: Long-term exposure may increase risk of skin, bladder, lung, kidney, and prostate cancers; also associated with cardiovascular problems and developmental issues in children
Current Levels: Mesa’s water contains 4.35 ppb arsenic — within the EPA legal limit but 1,087x above California’s health goal of 0.004 ppb. Reverse osmosis filtration is the most effective removal method. EPA MCL: 10 ppb. For filter recommendations, see our water filter solutions page.
Chromium-6
Source: Industrial activities, natural mineral deposits, and chromium-containing materials leaching into groundwater; more prevalent in certain geographic areas of the Phoenix Valley
Health Effects: EPA classifies chromium-6 as a probable human carcinogen; studies link long-term exposure to gastrointestinal and lung cancers. California’s public health goal is 0.02 ppb — a level Mesa’s water exceeds by 281 times.
Current Status: Mesa’s water contains 5.63 ppb chromium-6 — among the highest levels in the nation. There is no federal MCL for chromium-6 specifically (the total chromium MCL is 100 ppb, far above detected levels). California has a 10 ppb state limit. NSF-certified reverse osmosis or strong-base anion exchange filters are effective at reducing chromium-6. See our filter recommendations.
Disinfection Byproducts
Source: Formed when chlorine-based disinfectants react with naturally occurring organic matter in source water; concentrations tend to increase during hot desert summers
Health Effects: Long-term exposure to elevated trihalomethanes and haloacetic acids may increase risk of certain cancers and potentially affect liver, kidney, and central nervous system; EWG also notes that inhalation during showering can add to total exposure
Current Levels: Total trihalomethanes at 42.8 ppb (285x above EWG health guidelines but well below the EPA MCL) and haloacetic acids at 10.9 ppb (109x above EWG guidelines, below EPA MCL). Note: EWG guidelines are not legal limits. EPA MCLs: 80 ppb for TTHMs; 60 ppb for HAA5. For national context, visit our water quality tool.
PFAS Compounds
Source: Per- and polyfluoroalkyl substances from industrial processes, firefighting foams used at airports and military sites, and consumer products that can enter groundwater and surface water sources in the Phoenix Valley
Health Effects: Studies suggest potential impacts on the immune system, cholesterol levels, kidney and testicular cancer risk, and developmental effects; the EPA has designated PFOA and PFOS as hazardous substances under CERCLA
Current Regulatory Status (2026): PFHxS detected at 0.231 ppt. In May 2025, EPA confirmed it intends to rescind the MCL for PFHxS, reducing regulatory pressure on this specific compound. The 4 ppt MCLs for PFOA and PFOS remain in force, with the compliance deadline extended to 2031. ADEQ is conducting statewide PFAS monitoring with testing required for all Arizona public water systems. For the latest PFAS regulatory developments, check our water alert news page.
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