Tucson, Arizona
Tucson Water Quality
Most Tucson tap water is Colorado River water that was banked in the aquifer and recovered through wells — not canal water chlorinated and sent straight out. That is why the byproduct numbers look different from the Valley.
The 2024 main-system CCR lists arsenic up to 6.64 ppb, TTHM averaging 26.3 ppb, HAA5 averaging 2.2 ppb, and nitrate up to 7.2 ppm — all while meeting federal limits. Isolated systems have their own reports.
The short answer
Tucson Water's main system (PWS AZ0410112) served about 241,000 households and businesses in 2024. About 78 percent of that supply is Colorado River water recharged at CAVSARP, Pima Mine Road and SAVSARP and recovered through wells; about 22 percent is the Central Well Field. That design is why disinfection byproducts sit well below typical Phoenix-metro surface-water ranges.
Arsenic and nitrate are the dissolved inorganics the 2024 report actually lists at levels a household might choose to filter. Hardness is real in the basin; we are not inventing a grain figure the CCR tables did not print. A test at your tap is still the first step, and coverage is confirmed per service area.
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Tell us your Tucson-area address. We confirm coverage — and which Tucson Water system you are actually on — before anyone schedules a test.
What filtration does — and does not
Recharge already does part of the byproduct job. What is left is a household question about arsenic, nitrate and whatever your own plumbing adds.
Where Tucson water comes from
This is not a Valley canal-and-blend story. Recharge, recovery and a remaining well field are the local facts.
Direct recovered recharged water — about 78 percent
Colorado River water delivered by the Central Arizona Project, banked in the aquifer at CAVSARP (2001), Pima Mine Road (joint with CAWCD, 2001) and SAVSARP (2008), then recovered through wells. Soil-aquifer treatment is why Tucson's disinfection-byproduct numbers look different from a city that chlorinates canal water and sends it straight out.
Central Well Field — about 22 percent
The historical groundwater supply. Today it covers peak demand, backs up the renewable supply, and is the long-term savings account. One hundred thirty-nine active potable wells sit on the main system. Well-field chemistry is where arsenic and nitrate variation comes from.
Isolated systems are not this page
Tucson Water also publishes separate CCRs for Catalina, Corona de Tucson, Diamond Bell, Rancho Del Sol Lindo, Sierrita Foothills, Silverbell West, Thunderhead Ranch and Valley View. If you are on one of those, the main-system figures on this page do not apply. Coverage is confirmed at the address.
What the 2024 main-system report actually says
Federal MCLs are fixed. The ranges are from Tucson Water's 2024 Annual Water Quality Report for PWS ID AZ0410112. A later CCR supersedes them. Isolated systems are not in these numbers.
Arsenic
Naturally occurring in basin groundwater. Federal MCL 10 ppb. The 2024 main-system report lists a high of 6.64 ppb and a range of not-detected to 6.64 ppb. Below the MCL, and not zero. Reverse osmosis is the residential treatment; a carbon pitcher is not.
Total trihalomethanes (TTHM)
Federal MCL 80 ppb. The 2024 report lists a highest locational running annual average of 26.3 ppb and a range of 3.1 to 39.3 ppb. That is substantially lower than typical Phoenix-metro surface-water numbers, which is the point of soil-aquifer treatment: CAP water is recharged, recovered, and no longer a raw canal supply at the tap. Activated carbon still addresses what remains.
Haloacetic acids (HAA5)
Federal MCL 60 ppb. The 2024 report lists a highest locational running annual average of 2.2 ppb and a range of not-detected to 3.2 ppb. Low, not zero, and not a reason to buy a whole-house system on its own.
Nitrate
Federal MCL 10 ppm. The 2024 report lists a high of 7.2 ppm and a range of not-detected to 7.2 ppm. The CCR itself flags the infant-health language at levels above 10 ppm and advises anyone caring for an infant to ask a clinician if detected levels are above 5 ppm. Reverse osmosis addresses nitrate at the tap; a softener does not.
Fluoride and sodium
Fluoride 0.13 to 0.59 ppm against a federal MCL of 4 ppm (2024). Sodium 24.5 to 40.8 ppm, unregulated. Neither is a reason to filter on its own. Sodium matters if a household is considering a salt-based softener on top of an already mineralised supply.
What we are not putting on this page
A hardness grain figure we did not find in the 2024 main-system tables, a 2025 CCR that is not yet published, or numbers from Catalina, Corona de Tucson or the other isolated systems. Those systems have their own reports. This page is the main system only.
Where these figures come from
Every concentration on this page is taken from the 2024 main-system Consumer Confidence Report. The 2025 CCR had not been published at the time of writing.
- Tucson Water 2024 Annual Water Quality Report — Main System (PDF) — CCR for PWS ID AZ0410112.
- Tucson Water 2024 report archive — main system plus isolated-system CCRs.
- EPA National Primary Drinking Water Regulations
- EPA SDWIS Federal Reports — search AZ0410112.
Matching treatment to the finding
Do not buy a Phoenix-metro package for a Tucson chemistry. The byproduct story is different; arsenic and nitrate may not be.
Reverse osmosis, at the tap
The residential option for arsenic and nitrate. Under-sink for drinking and cooking. Tucson's lower byproduct numbers do not make RO unnecessary if a tap test finds a dissolved inorganic.
Activated carbon
Still the matching treatment for remaining chlorine byproducts and taste, even when TTHM and HAA5 sit well below Phoenix-metro ranges.
Softening, only if a test says so
We are not putting an invented hardness number on this page. Hard water is common in the basin; whether your house needs a softener is a tap and plumbing question, not a citywide one.
Sometimes nothing
Tucson's recharge-and-recovery design already does a large part of what a filter is sold to do for byproducts. If a test comes back unremarkable, that is the finding.
How the free test works
A licensed technician tests at your kitchen tap and tells you which of the problems above applies to your house. No charge, no obligation.
Seamless Home is the licensed contractor of record. Installation is performed by vetted installing partners engaged as our subcontractors. Coverage is confirmed per service area rather than promised as blanket availability.
Tucson water, answered plainly
Is Tucson tap water safe to drink?+
Tucson Water's main system, public water system identifier AZ0410112, is treated to federal standards and the 2024 Consumer Confidence Report publishes the results. A compliant system can still contain compounds a household would rather filter. That is a statement about how federal limits are set, not an allegation about the utility.
Why are Tucson's TTHM numbers lower than Phoenix-area cities?+
Because most of the Colorado River water Tucson uses is recharged into the aquifer and recovered through wells rather than chlorinated as raw canal water and sent straight into the pipes. Soil-aquifer treatment reduces the organic load that forms disinfection byproducts. The 2024 main-system TTHM locational running annual average is 26.3 ppb against a federal MCL of 80. That is a design difference, not a reason to skip a tap test.
Didn't Tucson have a water-quality crisis when it first used CAP water?+
In the 1990s, delivering Colorado River water directly into a distribution system built around groundwater caused taste, colour and corrosion complaints, and the City reversed course. The current design — recharge, recover, blend with the Central Well Field — is the long answer to that history. We are not relitigating it, and we are not using it as a sales story. The 2024 CCR is the current source of truth.
I live in Corona de Tucson / Catalina. Is this my report?+
No. Those are isolated Tucson Water systems with their own Consumer Confidence Reports. This page is the main system, AZ0410112. Tell us the address and we will confirm which system you are actually on before anyone talks about equipment.
How do I find the measured numbers?+
The 2024 Annual Water Quality Report for the main system is the current published CCR as of this page. Search EPA SDWIS under AZ0410112. A later report supersedes these figures.
What does treatment cost in Tucson?+
It depends on which equipment your results justify. We do not publish a figure for your house on a web page. The test is free.
Who does the installation, and who is responsible afterwards?+
Seamless Home is the licensed contractor of record. Installation is performed by vetted installing partners engaged as our subcontractors, and the workmanship obligation stays with us. Coverage is confirmed per service area rather than promised as blanket availability.
Related resources
Home water purification and treatment
The national service page: what each treatment stage removes, and why a test comes first.
Learn more →Phoenix water quality
The Valley contrast: canal water, higher TTHM, hardness to 17.6 grains.
Learn more →Mesa water quality
East Valley zones and a 2025 CCR with hardness from 0.4 to 25 grains.
Learn more →All homeowner services
Water treatment, battery backup, HVAC and solar under one licensed contractor of record.
Learn more →Get a free test at your tap
A licensed technician tests at your kitchen tap and tells you which of the problems above applies to your house — and which does not. Coverage confirmed at your address first.
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