Mesa – Arizona – Water Quality Report 2025: PFAS Testing, Infrastructure Concerns & Safety across your city
Mesa Water Resources provides comprehensive water and wastewater services to approximately 530,000 residents across Arizona’s third-largest city, spanning over 130 square miles in the east Valley of metropolitan Phoenix. Established as a municipal utility, the system encompasses an extensive distribution network, three major water treatment facilities, and over 30 groundwater wells that deliver 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 state-of-the-art 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. Mesa’s water consistently meets all federal and state quality standards, though the desert community faces ongoing challenges with water conservation, infrastructure modernization, arsenic management, and emerging contaminants like PFAS. The utility has implemented significant investments in advanced treatment technologies, aggressive conservation programs, and sustainable water management to ensure reliable supply for future generations in the arid Southwest.
Mesa Water Quality: Current Status (2024-2025)
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 regulations.
- Testing Scope: Mesa conducts over 18,500 water quality analyses annually on approximately 3,100 samples collected from treatment facilities and throughout the distribution network to meet regulatory requirements.
- Lead and Copper Monitoring: The most recent lead and copper testing in 2022 showed full compliance with EPA action levels, with 90th percentile values well below federal thresholds at all 50 monitored residential locations.
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 facility.
- 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: 30+ deep aquifer wells provide approximately 19% of supply, with 16 wells serving the City Zone and 15 wells serving the Eastern Zones, offering backup capacity and system redundancy.
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: The newest facility, completed in 2018, features cutting-edge ozone disinfection technology with 24 MGD capacity to serve southeast Mesa’s growing population.
- Arsenic Removal Systems: All treatment facilities incorporate specialized treatment processes to ensure arsenic levels remain well below the EPA maximum contaminant level of 10 ppb, addressing naturally occurring desert minerals.
Infrastructure Modernization
- Smart Water Management: Implementation of advanced monitoring systems throughout the distribution network for real-time water quality tracking, leak detection, and pressure management across Mesa’s 130+ square miles.
- Distribution System Improvements: Ongoing replacement and upgrade of aging water mains and service lines, with priority given to areas with highest vulnerability assessments and customer demand growth.
- Emergency Preparedness: Multiple source redundancy and interconnected treatment facilities provide resilience against supply disruptions, drought conditions, and emergency situations in the desert environment.
Customer Protection Initiatives
Mesa Water Resources offers comprehensive customer support including water quality testing assistance, the Utility Customer Assistance Program for qualifying low-income residents, and extensive educational outreach about desert water conservation. Mesa’s commitment to transparency includes detailed annual Consumer Confidence Reports and regular community updates about water quality monitoring results. The utility’s significant investments in treatment technology, source water diversification, and proactive management of desert-specific challenges like arsenic and high mineral content demonstrate Mesa’s dedication to providing safe, reliable drinking water while addressing the unique demands of rapid population growth and extreme desert climate conditions.
Recommendations for Mesa Residents
Request Water Testing
Contact Mesa Water Resources at 480-644-2221 for water quality testing assistance or concerns. While not offering free testing kits like some utilities, Mesa provides detailed annual water quality reports and can direct residents to certified testing laboratories.
Maximize Water Conservation
Take advantage of Mesa’s Grass-to-Xeriscape (G2X) program offering $500 rebates for converting 500+ sq ft of grass to desert landscaping. Combine with the “Trees Are Cool” program for additional $50-$100 tree planting incentives.
Consider Home Filtration
While Mesa’s water meets EPA standards, homes concerned about arsenic, chromium-6, or disinfection byproducts may benefit from NSF-certified filters designed for desert water conditions and naturally occurring minerals.
Join Commercial Conservation Programs
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 about available incentives.
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 Center at 480-644-2262 to report leaks, pressure problems, or outages.
Frequently Asked Questions
Is Mesa’s tap water safe to drink?
Yes, Mesa’s tap water meets all federal and state drinking water standards. The city’s water comes from three sources: Colorado River (CAP), Salt/Verde Rivers (SRP), and local groundwater, all treated at state-of-the-art facilities.
Mesa Water Resources conducts over 18,500 tests annually across its three treatment facilities to ensure water quality. Advanced treatment processes including filtration, disinfection, and specialized arsenic removal provide multiple barriers against contaminants. Mesa’s commitment to transparency is demonstrated through detailed annual Consumer Confidence Reports available to all customers and proactive communication about water quality monitoring results.
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 programs rather than mandatory restrictions, recognizing that desert residents typically practice natural conservation.
Landscape Guidelines: The city promotes desert-adapted landscaping through rebate programs 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.
Why does my water sometimes have a mineral taste?
Mesa’s desert location and diverse water sources can occasionally affect taste and mineral content:
Natural Minerals: Groundwater wells may contain naturally occurring minerals common in desert aquifers, which can create a slightly mineral taste that varies by location and season.
Source Water Variations: Different water sources (CAP, SRP, groundwater) have distinct mineral profiles, and the blend delivered to your area may change based on operational needs and supply conditions.
Treatment Processes: Water treatment chemicals, including disinfectants and pH adjustment compounds, may occasionally be noticeable, especially during hot weather when chemical reactions can be more pronounced.
If taste issues persist or worsen, contact Mesa Water Resources at 480-644-2221. Running water for a few minutes after periods of non-use can often help improve taste from your tap.
Does Mesa’s water contain lead?
Mesa Water Resources maintains compliance with all lead and copper regulations:
• Recent Testing: The most recent lead and copper monitoring in 2022 showed full compliance with EPA action levels, with 90th percentile values well below federal limits at all 50 residential monitoring sites
• Source Water: Mesa’s treated water sources are not known to contain lead, as contamination typically occurs in home plumbing systems rather than city infrastructure
• Home Plumbing: Homes built before 1986 may have lead-containing solder or fixtures in internal plumbing, which is why residents with concerns should consider testing
• Testing Resources: Mesa provides information about certified laboratories for home testing and maintains detailed monitoring records available in annual water quality reports
Mesa will continue comprehensive lead and copper monitoring every three years as required by EPA regulations, with next testing scheduled for 2025.
Contaminants of Concern
Arsenic
Source: Naturally occurring in desert soils and bedrock throughout Arizona, leaching into groundwater aquifers; concentrations can vary by well location and seasonal groundwater levels
Health Effects: Long-term exposure to elevated levels may increase risk of skin, bladder, lung, kidney, and prostate cancers; also associated with cardiovascular problems and developmental issues
Current Levels: Mesa’s water treatment facilities effectively remove arsenic to levels well below the EPA maximum contaminant level of 10 ppb across all water sources EPA Limit: 10 ppb maximum contaminant level
Chromium-6
Source: Industrial activities, natural mineral deposits, and chromium-containing materials that can leach into groundwater sources; more prevalent in certain geographic areas of the Valley
Health Effects: Studies suggest potential links to certain cancers, particularly when exposure occurs over extended periods; EPA classifies chromium-6 as a probable human carcinogen
Current Status: Third-party testing has detected chromium-6 in Mesa’s water at levels above health guidelines, though no federal limit currently exists; Mesa continues monitoring and treatment optimization EPA Status: Currently unregulated federally, though California has set a 10 ppb limit
Disinfection Byproducts
Source: Formed when chlorine-based disinfectants react with naturally occurring organic matter in source water; concentrations may increase during hot desert summers
Health Effects: Long-term exposure to elevated levels of trihalomethanes and haloacetic acids may increase risk of certain cancers and potentially affect liver, kidney, and central nervous system
Current Levels: Monitored quarterly throughout Mesa’s distribution system with levels maintained below EPA maximum contaminant levels EPA Limits: 80 ppb for total trihalomethanes (TTHMs) and 60 ppb for haloacetic acids (HAA5)
PFAS Compounds
Source: Per- and polyfluoroalkyl substances from industrial processes, firefighting foams used at airports, and consumer products that can enter groundwater and surface water sources
Health Effects: Studies suggest potential impacts on immune system, cholesterol levels, kidney and testicular cancer risk, and developmental effects; research continues on long-term health implications
Current Status: Mesa is monitoring PFAS compounds as part of EPA’s Unregulated Contaminant Monitoring Rule; preparing for new federal regulations that will require detection and treatment EPA Limits: New federal standards set 4 ppt maximum for PFOA and PFOS, effective 2029
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