Phoenix has a complicated water quality situation that's easy to get wrong in both directions. Some sources describe it as a crisis. The city calls it safe. The honest answer is somewhere more specific: Phoenix water meets every federal standard, but it has two genuine health concerns — arsenic and chromium-6 — and one major nuisance problem that costs residents real money every year.
Here's what the data actually shows.
Where Phoenix Gets Its Water
Phoenix draws from three river systems: the Salt and Verde rivers (via Salt River Project canals, about 60% of supply), the Colorado River (via the Central Arizona Project aqueduct, about 29%), and local groundwater wells (about 11%). All surface water is processed at six major treatment plants before reaching taps.
The treatment is sophisticated — Phoenix uses membrane filtration, ozonation, and biological activated carbon, which is more advanced than most US cities. The water leaving the plants is genuinely well-treated. The contamination issues in Phoenix water come primarily from the source water itself: the natural geology of Arizona's desert basin aquifers concentrates certain minerals, particularly arsenic.
The Arsenic Issue
Arsenic in Phoenix water comes almost entirely from natural sources — Arizona's Basin and Range geology contains arsenic-bearing minerals that leach into groundwater and surface water supplies. It's not industrial pollution; it's the geology.
Phoenix's water has tested with arsenic levels up to 8.3 parts per billion (ppb) in recent reporting. The EPA's Maximum Contaminant Level for arsenic is 10 ppb — and Phoenix's water meets that standard. But the science on arsenic has significantly evolved since that standard was set in 2001.
The EPA's own Maximum Contaminant Level Goal (MCLG) for arsenic is 0 ppb — meaning the agency acknowledges no level of arsenic in drinking water is considered completely safe. The EWG's health-based guideline is even lower: 0.004 ppb. At Phoenix's levels of up to 8.3 ppb, that's more than 1,000 times the EWG threshold, though comparison is somewhat misleading — the EPA's enforceable limit exists as a practical balance between health protection and treatment cost.
The important context: The health risk from arsenic at Phoenix's levels is real but long-term. Arsenic in drinking water is associated with bladder, lung, and skin cancers, cardiovascular disease, and developmental effects — but these are risks from years of cumulative exposure, not from occasional drinking. No one is getting acutely ill from Phoenix tap water. But if you're drinking Phoenix water daily for years or decades, filtering arsenic out of your drinking water is a reasonable and inexpensive precaution.
What removes arsenic: Reverse osmosis (RO) removes 94–96% of arsenic. Activated alumina and iron-based filter media also reduce it. Standard carbon filters, Brita pitchers, and most faucet-mount filters do not meaningfully remove arsenic.
Chromium-6
Phoenix has among the highest chromium-6 levels of any major US city, at roughly 7.85 ppb in some testing periods — about 20 times EWG's health guideline of 0.02 ppb. (Some sources cite different specific numbers depending on the testing period; the consistent picture is that Phoenix chromium-6 is elevated relative to health-based thresholds, though well under the federal total chromium limit of 100 ppb.)
There is currently no federal MCL specifically for hexavalent chromium (chromium-6). California established one at 10 ppt in 2024 — far stricter than Phoenix's current levels. Chromium-6 is classified as a known human carcinogen when inhaled and a probable carcinogen in drinking water.
Like arsenic, this is a long-term chronic exposure concern, not an acute hazard. Reverse osmosis removes chromium-6 effectively.
Hard Water: The Daily Nuisance With Real Costs
Phoenix water is extremely hard — typically 18–19 grains per gallon (GPG), which is classified as very hard to extremely hard. For comparison, "moderately hard" is 7–10 GPG; Phoenix is roughly double that.
Hard water itself is not a health hazard. But at Phoenix's hardness levels:
- Water heaters lose efficiency and need replacement 30–40% sooner
- Dishwashers and washing machines accumulate scale damage
- Faucets and showerheads clog with mineral deposits
- Soap and detergents lather poorly, requiring more product
- Hair and skin dry out more noticeably
A water softener that addresses hardness can pay for itself relatively quickly in Phoenix given these levels. However, softeners do not address arsenic, chromium-6, or disinfection byproducts. A softener + under-sink RO for drinking water is the comprehensive approach many Phoenix homeowners use.
Disinfection Byproducts
Phoenix uses both chlorine and chlorine dioxide for disinfection, which produces disinfection byproducts including trihalomethanes (TTHMs) and haloacetic acids (HAA5), plus chlorite and bromate.
Phoenix's 2024 testing showed TTHMs up to 59 ppb (EPA limit: 80 ppb) and chlorite up to 0.6 ppm (EPA limit: 1 ppm). These are in compliance but not zero. Long-term exposure to TTHMs and HAAs has been associated with bladder cancer and other concerns. Reverse osmosis and activated carbon filters both reduce these compounds.
What Filter Makes Sense for Phoenix
The combination of arsenic, chromium-6, DBPs, and extreme hardness points to a two-system approach for most Phoenix homeowners:
For drinking and cooking water:
Reverse osmosis is the clear choice for Phoenix — it's the only filter technology that effectively addresses arsenic, chromium-6, DBPs, and fluoride simultaneously.
- APEC ROES-50 Under-Sink RO (~$215) — NSF 58 certified, excellent value, reliable performer
- Waterdrop G3P600 Tankless RO (~$400) — no storage tank, fast flow, compact
- Bluevua RO100ROPOT-LITE Countertop RO (~$299) — for renters or anyone avoiding installation
Note: RO filters do reduce total dissolved minerals, including beneficial ones. Some Phoenix residents prefer a remineralization stage added to their RO — the iSpring RCC7AK (~$219) includes this.
For whole-house hard water:
A salt-based water softener sized to Phoenix's water hardness (18–19 GPG is very high; make sure the softener is spec'd accordingly) will protect appliances, pipes, and fixtures. This is separate from drinking water filtration — a softener does not remove arsenic or chromium-6.
For renters or budget-conscious residents:
A reverse osmosis pitcher is not a common product, but the Bluevua RO100ROPOT-LITE Countertop RO is the portable RO option that doesn't require installation. The Clearly Filtered pitcher (~$90) doesn't use RO but is certified for a broad range of contaminants and is the best non-RO pitcher option.
What About Bottled Water?
Given Phoenix's arsenic levels, some residents default to bottled water for drinking. This is more expensive and produces plastic waste, and some bottled water brands have their own contamination issues (PFAS has been detected in multiple bottled water products). A reverse osmosis filter provides better-documented, more consistent protection at a fraction of the long-term cost.
Check Your Specific Water
Phoenix water quality varies somewhat by service area, treatment plant, and season — summer months often see different profiles than winter due to source water blending shifts.
→ Enter your ZIP at PureCity to see water quality data specific to your Phoenix neighborhood, including which contaminants have been detected and at what levels.
Related Articles
- PFAS in Drinking Water: What It Is, Where It's Found, and How to Filter It
- Nitrates in Well Water: What the Test Results Mean and How to Filter Them
Sources: City of Phoenix Water Quality Reports · EWG Tap Water Database: Phoenix · Aqua Science AZ: Phoenix Water Quality Guide · EPA Arsenic in Drinking Water · HomeWater: Phoenix Water Quality Deep Dive · NSF Certified Products Database