Latest Testing Results

• Overall Compliance: Scottsdale Water met all federal and state drinking water standards in its 2024 Water Quality Report (covering 2023 monitoring data). The system tests for over 100 substances at eight entry points to the distribution system and at 150 locations throughout the network. Note: one Tier 3 public notice was issued for a missed TOC monitoring test in August 2023 — this was a procedural gap, not a health event.
• Arsenic: Maximum 7.7 ppb, average 3.7 ppb, highest running annual average 7.7 ppb. Naturally occurring from geological leaching. Three dedicated arsenic treatment facilities operate to manage groundwater sources. Meets the EPA MCL of 10 ppb; however, the MCLG is 0 ppb — arsenic is a known human carcinogen at high concentrations.
• Total Chromium: Maximum 31.7 ppb, average 5.9 ppb. Meets the federal MCL of 100 ppb. Scottsdale’s official 2024 report notes total chromium, not specifically hexavalent chromium-6. The source is natural leaching from deposits; no specific federal MCL exists for chromium-6 alone, but the compound is linked to increased cancer risk with long-term exposure above health benchmarks.
• Uranium: Maximum 14 ppb, average 4.5 ppb. Meets the EPA MCL of 30 ppb; MCLG is 0 ppb. From natural geological leaching. Long-term exposure above health benchmarks is associated with kidney damage and increased cancer risk.
• Disinfection Byproducts (DBPs): Total trihalomethanes (TTHM) highest LRAA 55.5 ppb (max 58.7 ppb; MCL 80 ppb). Haloacetic acids highest LRAA 10.6 ppb (max 14 ppb; MCL 60 ppb). Both within compliance. Scottsdale uses granular activated carbon (GAC) at both the CAP and Chaparral plants to minimise organic matter and reduce DBP formation. Long-term exposure above MCLGs is linked to bladder cancer and liver/kidney effects.
• Lead and Copper: 90th percentile lead level was 2 ppb (action level 15 ppb) — well within the standard. However, 1 of 50 homes tested exceeded 15 ppb, triggering required follow-up with that homeowner. System-level treated water registers ND for both lead and copper. Scottsdale completed its Lead Service Line Inventory in October 2024 in compliance with the EPA’s 2024 Lead and Copper Rule Revisions.
• Nitrate: Maximum 3.4 ppm, average 1.1 ppm — well below the MCL of 10 ppm. No concern for most residents, though infants under six months should have water assessed by a healthcare provider if levels rise.
• Barium: Maximum 122 ppb (avg 70 ppb) — within MCL of 2,000 ppb; naturally occurring from geological leaching.
• PFAS: Not reported in the 2024 Water Quality Report covering 2023 data. Arizona is subject to the EPA’s national PFAS MCLs (4 ppt for PFOS/PFOA, finalised April 2024), with initial monitoring required by April 2027 and compliance by 2029–2031. Statewide testing data indicates approximately 10% of Arizona water systems have detections above federal standards. For the latest PFAS regulatory updates, see our water alert news section.

Water Sources

• Central Arizona Project (CAP) — ~70%: Colorado River water transported through a 336-mile aqueduct and treated at the CAP Water Treatment Plant (up to 70 million gallons per day). CAP I and II use conventional treatment (coagulation, flocculation, sedimentation, filtration, disinfection); CAP III uses ultrafiltration membrane technology. All three lines use granular activated carbon for taste, odour, and DBP reduction.
• Salt River Project (SRP) — ~16%: Verde and Salt River watershed water processed at the Chaparral Water Treatment Plant (27 million gallons per day) using ultrafiltration membranes and granular activated carbon.
• Groundwater — ~10%: 21 active wells drawing from desert aquifers. Treated at the Central Groundwater Treatment Facility and the North Indian Bend Wash GAC Treatment Facility — the latter addressing Trichloroethylene (TCE) contamination from the North Indian Bend Wash Superfund Site, with operating costs paid by the responsible private companies.
• Recycled Water — ~4%: Highly purified water from the Advanced Water Treatment Plant at the Scottsdale Water Campus, used for turf irrigation and aquifer recharge (over 70 billion gallons recharged since 1998). Full-scale advanced purified recycled water (APRW) for drinking use is planned as early as 2027.

Treatment Technology and Innovation

• Multi-barrier Treatment: Both surface water plants use ultrafiltration membranes and granular activated carbon alongside conventional coagulation/filtration/disinfection — providing multiple independent barriers against microbial and chemical contamination.
• Arsenic Treatment: Three dedicated groundwater arsenic treatment facilities ensure all well water meets the MCL before entering the distribution system.
• Microbiological Monitoring: Monthly testing at over 150 distribution system sites for Total Coliform and E. coli. In 2023, total coliform was detected in 0.6% of monthly samples (MCL threshold: 5%) — within compliance.
• Colorado River Shortage Preparedness: Since 2022, Scottsdale has operated under Arizona’s CAP shortage allocation. The city’s Drought Management Plan, diversified water portfolio, and Aquifer Storage and Recovery programme reduce vulnerability to further Colorado River cuts anticipated through the late 2020s.

For information on boil water advisories in Scottsdale or across Arizona, visit our live boil water notices tracker. Use our water quality checker to explore contaminant data for your area.