How do I read my tap water quality report?

The EPA requires community water systems to send customers a report every year by July 1. The CDC explains that you should get it in the mail or be able to see it online, and the EPA maintains a page for finding your report by location. The report is called a Consumer Confidence Report, or CCR.

A few situations mean you may not get one.

• You rent, or a manager pays the water bill. The CDC says you may not receive a report directly, so check online or ask your building manager or landlord.
• You are on a private well. Well owners do not get a report. The CDC recommends testing well water at least once a year for germs and chemicals.
• You are served by a system with its own supply, such as a hospital, a school or a campground, which the CDC lists as not getting a report.

If you are not sure who supplies your water, check your water bill. In the Valley, the city usually posts the current report on its water pages, and Phoenix, Mesa, Chandler and Tempe all do. Our page on what contaminants are in Arizona tap water walks through two of them.

The CDC says the report covers where your tap water comes from, the levels of germs and chemicals over the past year, the health risks of drinking water with those substances, and any violations in the past year. In practice you will see these sections.

• Water sources. Phoenix's 2025 report says about 97 to 99 percent of its water came from surface water, mostly the Salt, Verde and Colorado rivers, with the rest from city wells.
• A data table. This is the heart of it. Each row is a substance, with the highest allowed level, your utility's results and where the substance comes from.
• Definitions. Reports define their terms, and you will need them for the table.
• Health information. Reports include language on lead, arsenic, nitrate and germs such as Cryptosporidium. The CDC notes that this language appearing does not necessarily mean your water contains those substances.
• Violations. If the utility missed a standard or a rule, it must describe what happened, how long it lasted, whether it caused a health risk and how the utility is fixing it.

Use the terms the report defines. Phoenix and Mesa both define these, in the EPA's language.

• MCL (maximum contaminant level). The highest level of a contaminant allowed in drinking water. MCLs are set as close to the goals as feasible with the best available treatment technology. This is the number to compare against.
• MCLG (maximum contaminant level goal). The level below which there is no known or expected risk to health, with a margin of safety. The goal for some contaminants, like lead, is zero, which is lower than any enforceable limit.
• AL (action level). The concentration that, if exceeded, triggers treatment or other requirements. Lead and copper use action levels, not MCLs.
• TT (treatment technique). A required process meant to reduce a contaminant, used where an MCL does not apply.
• ppm and ppb. One part per million is one milligram per liter. One part per billion is one microgram per liter. Phoenix explains that one part per million is about one minute in two years, and one part per billion is about one minute in 1,920 years. Both are tiny.
• ND. Reports use this abbreviation, short for not detected, in results columns.
• Range and average. Results usually show a low to high range, and some show an average or the highest running annual average.

Here is a worked example from Phoenix's 2025 report. Arsenic has a limit of 10 parts per billion. The report shows results from not detected to 8.5, and a footnote adds that the water meets the standard while still containing low levels of arsenic. So the answer to "is it within the limit?" is yes, with room that is small enough to notice. Nitrate has a limit of 10 parts per million, and Phoenix's results ran from not detected to 4.5.

Now compare with Mesa. Its report shows a highest nitrate level of 8.99 parts per million, close to the limit of 10, and a highest arsenic level of 8.8 parts per billion. Two cities, same substances, different numbers, because their sources differ. This is why you read your own report and not a neighbor city's.

You can skim the report in about five minutes if you know where to look.

1. 1Violations. The CDC says to look for a column called violations or meets standard. A yes means a limit was exceeded or a rule was missed. Look back at earlier reports to see whether a problem is ongoing.
2. 2Numbers close to the limit. Nitrate, arsenic and disinfection byproducts are the usual ones. Being close is still compliant, but it tells you where the margin is thin.
3. 3Lead and copper. These are measured at customer taps, not at the plant. Phoenix's table shows a 90th percentile, which Mesa explains means 90 percent of samples were at or below that value. Also check how many sites were over the action level. Phoenix's 2024 sampling had two of 56 taps over the 15 parts per billion lead action level, and Mesa's had one sample over.
4. 4Monitoring results and newer limits. Phoenix's report lists two PFAS and lithium detected in EPA monitoring, and Mesa's says it completed that monitoring and points to the EPA's public data. Lithium has no drinking water standard. PFAS are changing: the EPA's regulations table now shows limits for PFOA and PFOS (4.0 parts per trillion each) and for PFHxS, PFNA, HFPO-DA and a hazard index mixture. Compare any PFAS in your report with the EPA's current table, not with the report's date alone.
5. 5Aesthetic items. Hardness, total dissolved solids, iron and pH are not health limits. Phoenix reports hardness of 172 to 302 milligrams per liter, or 10 to 17.6 grains per gallon. Our page on hardness by Valley city helps you read it.

The EPA's table of national drinking water regulations lists each contaminant's limit and the health effect of long-term exposure above it, which helps when a report's health language is thin.

The report describes the water the utility delivers to the system. It does not describe what comes out of your faucet, and the gap matters. Phoenix's report says lead comes primarily from service lines and home plumbing, and that lead levels vary over time, so lead exposure is possible even when a sample does not detect it. Mesa likewise says it cannot control the materials used in your home plumbing.

Three limits to remember.

• Your plumbing is not covered. Old pipes, fixtures and fittings can add metals and rust. Our page on how to test home water for lead shows how to check your own tap.
• Averages hide swings. A range from low to high tells you the water changes, and some reports list sources by zone. Mesa, for instance, has three zones with different hardness.
• Taste and looks are not safety signals. The CDC warns that harmful germs and chemicals often do not change how water looks, tastes or smells, and that harmless substances can make it taste bad.

If the report shows something you want to reduce, the CDC's advice is to test your water and choose a system that removes the specific chemical, checking the label. Our page on what removes heavy metals from tap water and how UV, carbon and RO treatment differ help you match a product to the problem. If your test or your report points at a plumbing fix, we can inspect the pipes and give an upfront price before work starts, and the estimate is free.

### Quick answers

Here are the short versions.

When do I get my report? By July 1 each year, if you are on a community water system.

Does "detected" mean unsafe? No. Compare the level with the limit. Phoenix's report says presence does not necessarily mean a health risk.

Where do I get answers? Your utility, your health department or the EPA Safe Drinking Water Hotline, which the CDC lists as 800-426-4791.

What if I am on a well? No report comes to you. Test at least once a year, per the CDC.