What contaminants are in Arizona tap water?

Here are the regulated substances each city detected, next to the federal limit, drawn from the 2025 reports.

Phoenix also reports selenium (not detected to 2.2 parts per billion against a 50 limit), xylenes at trace levels, uranium (not detected to 4.6 parts per billion against a 30 limit) and alpha emitters. Mesa lists gross alpha at 5.4 picocuries per liter against a 15 limit.

Mesa's report samples different years for different items, so the "highest level" is not always from 2025. Its chromium and fluoride values are from 2021, for example. That is normal, since some contaminants are tested on a multi-year schedule.

Two rows deserve a second look.

Arsenic is close to its limit in both cities. Phoenix's highest reading was 8.5 against a limit of 10, and Mesa's was 8.8. Phoenix says its water meets the standard while still containing low levels of arsenic, and Mesa says some of its sources contain low levels. Both note that the EPA continues to research the health effects of low-level exposure. Our page on arsenic in Arizona drinking water covers where it comes from and what to do about it.

Nitrate is the other one. Mesa's highest detected level was 8.99 parts per million against a limit of 10. Both cities' reports warn that nitrate above 10 parts per million is a health risk for infants younger than six months, and that it can cause blue baby syndrome. Phoenix adds that levels can rise quickly for short periods because of rainfall or agricultural activity, and advises anyone caring for an infant to ask a health care provider.

The EPA table and the city reports name the same sources over and over.

• Erosion of natural deposits. This is the source for arsenic, barium, chromium, fluoride, radium and uranium. The rock and soil in the Southwest release small amounts of these into water that crosses or sits in them.
• Runoff and septic leaching. Nitrate comes from fertilizer runoff, leaking septic tanks and sewage, as well as natural deposits.
• Fluoride added on purpose. Phoenix adds a small amount of fluoride to prevent tooth decay. Its detected range is 0.3 to 1.1 parts per million, and the federal limit is 4.
• Disinfection. Phoenix adds chlorine to kill disease-causing microorganisms and prevent microbial growth. Its chlorine running annual average was 0.84 parts per million, and the federal limit is 4. Disinfection also produces byproducts. Mesa's highest byproduct readings were total trihalomethanes at 57 parts per billion against a limit of 80, and haloacetic acids at 25 against a limit of 60.

The health effects the EPA lists for going over these limits over the long term run from skin damage and circulatory problems (arsenic), to blood pressure increases (barium), to allergic dermatitis (chromium), to bone disease and mottled teeth in children (fluoride). The point of a limit is to keep the water far from those effects.

### What about lead and copper?

Lead and copper are different because they usually do not come from the water source. Phoenix's report says lead in drinking water comes primarily from service lines and home plumbing, and that the city cannot control which materials were used inside your home. Copper likewise enters water mostly through corrosion of household plumbing.

The reports show what tap sampling found.

• Phoenix (2024 sampling): lead from not detected to 41.8 parts per billion, 90 percent of taps at or below 3 parts per billion, and two of 56 taps above the 15 parts per billion action level. Copper from 0.04 to 0.5 parts per million against an action level of 1.3, with no taps over.
• Mesa (2024 sampling): a lead 90th percentile of 5.01 parts per billion, with one sample over the action level, and a copper 90th percentile of 0.17 parts per million.

Both cities say the same thing about home exposure. Lead levels can vary over time, so a clean result at one point does not rule out exposure. For a home built before lead-free rules, older galvanized or soldered plumbing, or a baby on formula, test your own tap. Our page on how to test home water for lead shows how.

### Are PFAS in Arizona water?

Yes, in trace amounts. PFAS are a group of thousands of man-made chemicals used in products such as non-stick cookware, water-repellent clothing, stain-resistant carpet and firefighting foam. Under the EPA's fifth Unregulated Contaminant Monitoring Rule, public water systems tested for 29 PFAS compounds and lithium between January 2023 and December 2025. Mesa says it completed that round and sent the results to the EPA, which will use them to help decide future limits.

Phoenix's report lists what it detected in that monitoring, including two PFAS. PFBS ranged from 0.007 to 0.016 parts per billion and PFBA from 0.005 to 0.006 parts per billion, and the report shows lithium from 22.2 to 160 parts per billion, with an average of 70.2. These are unregulated substances, meaning the EPA had not set a drinking water standard for them at the time of the reports. Your own city's report will list what it found. The EPA's monitoring data, which Mesa links in its report, is public.

Not in the health sense. The EPA calls these secondary standards. They are non-enforceable guidelines for taste, color and odor, and the EPA says water above them may look or taste bad even when it is safe to drink.

Phoenix's report lists some of them. Total dissolved solids ran from 464 to 716 parts per million against a 500 guideline, sodium from 91 to 183, pH from 6.6 to 8.8 against a 6.5 to 8.5 guideline, and iron from not detected to 30 parts per billion against a 300 guideline. Hardness was 172 to 302 milligrams per liter, or 10 to 17.6 grains per gallon. Phoenix calls taste, odor and hardness harmless aesthetic aspects. For city by city numbers, see our page on hardness in Phoenix, Mesa, Chandler and Tempe. If your complaint is a smell or taste, why Phoenix tap water can taste like chlorine explains it, and why tap water turns cloudy covers the look.

Start with your own city or water provider, since every system publishes a different mix.

1. 1Find your latest annual water quality report. It is also called a Consumer Confidence Report, and most cities post it on their water pages.
2. 2Compare each detected value with its limit. The table above shows how. A value under the limit means the system is in compliance.
3. 3Note the ones that matter for your household. Infants and nitrate, lead in older plumbing, and arsenic for long-term exposure are the usual ones.
4. 4Test your own tap when the risk sits in your plumbing. Lead and copper are the main ones.
5. 5Choose treatment to match the contaminant. A filter that fixes chlorine taste does not fix arsenic. Our page on what removes heavy metals from tap water explains which types fit, and whether reverse osmosis is worth it covers the most common under-sink option.
6. 6Follow the maintenance rules. Phoenix warns in its report that not following the manufacturer's instructions for a home treatment system can result in potentially unsafe water.

If you are on a private well, none of these city numbers apply, and a lab test is the only reliable answer. And if the results point to a plumbing fix, such as replacing old fittings or a service line, we can inspect it and give an upfront price before work starts, with a free estimate.

### Quick answers

Here are the short versions.

Is Arizona tap water safe to drink? For the cities checked here, the reports show every regulated contaminant below its federal limit. Your own water provider's report is the source for your address.

What is the most common contaminant? Naturally occurring minerals such as arsenic, barium and fluoride show up in both city reports, along with nitrate and disinfection byproducts.

Does bottled water avoid all of this? Not necessarily. The Phoenix report notes that the FDA sets limits for contaminants in bottled water, and that it is reasonable to expect drinking water of any kind, bottled or home-treated, to contain at least small amounts of some contaminants.

Should I install a filter? Only if your test shows something you want to reduce, or you want to change taste and odor. Match the product to the contaminant.