Is Flagstaff, AZ Tap Water Safe to Drink?
Yes, Flagstaff tap water is safe to drink. Hardness is low at 70 PPM, and no contaminants exceed health guidelines. Most homes here don't need treatment.
Hardness Scale: Where Flagstaff Falls
0Slightly
60Moderate
120Hard
180Very Hard
250Extreme
400+
How Flagstaff Compares
Flagstaff's water is 49% softer than the national average of 138 PPM - ranking in the bottom 63% for hardness nationwide. Most homes here do not need a softener. Within Arizona, it ranks #25 of 25 cities (73% below the state average of 257 PPM). Among cities (50k-100k), Flagstaff ranks #180 of 258 for hardness.
What Flagstaff's Water Means for Your Home
Hardness: 70 PPM - Low Concern
Flagstaff's water is moderately hard at 70 PPM. You'll see some spotting on glassware and a film on shower doors over time, but it's not the kind of hardness that demands a full softener. A salt-free conditioner is worth considering if you have a tankless water heater or high-end fixtures.
Contaminants & Safety
Disinfection byproducts are the notable finding here. Flagstaff's water has TTHMs at 17.3 ppb and HAA5 at 6.17 ppb — both within legal limits, but the EWG health guidelines are far stricter. These byproducts form when chlorine reacts with organic matter during treatment. A whole-house activated carbon filter reduces both chlorine and its byproducts. Want the full picture? Request your utility's annual Consumer Confidence Report.
What's in the Treatment Process
Flagstaff's surface water supply requires heavy chlorination to stay safe — but that creates a tradeoff. The treatment process generates disinfection byproducts: TTHMs at 17.3 ppb (22% of the legal limit, but 115x the EWG guideline) and HAA5 at 6.17 ppb (10% of the legal limit, but 62x the EWG guideline). These are within legal limits, but the EWG sets much tighter thresholds based on cancer-risk research. A whole-house activated carbon filter reduces both chlorine and byproducts.
Chromium-6 was detected at 1.31 ppb, which is 66x the EWG health guideline. There's no separate federal limit for chromium-6, only total chromium. A reverse osmosis system is the most effective removal method. All measurements are within federal legal limits. The EWG guidelines represent a more conservative, health-based standard.
| Contaminant | Detected | Health Guideline | Legal Limit | Status |
|---|---|---|---|---|
| Hardness (as CaCO₃) | 70 PPM | < 60 PPM | No federal limit | ✓ OK |
| Total Dissolved Solids | 165 PPM | < 300 PPM | 500 PPM | ✓ OK |
| PFAS (total) | 6.1 ppt | — | No total limit | Detected |
| ↳ PFOA | 0 ppt | 0 ppt | 4 ppt (2024) | ✓ OK |
| ↳ PFOS | 0 ppt | 0 ppt | 4 ppt (2024) | ✓ OK |
| Lead | 2.9 ppb | 0 ppb (no safe level) | 15 ppb (10 ppb in 2027) | ✓ Low |
| Chlorine / Chloramine | 0.6 mg/L | Taste threshold ~1.0 | 4.0 mg/L | ✓ Normal |
| Nitrate | 0.589 mg/L | 5 mg/L | 10 mg/L | ✓ OK |
Recommendations for Flagstaff Homes
How to Test Your Water in Flagstaff
City-wide data is a solid starting point, but your specific tap might differ based on plumbing age, distance from the treatment plant, or seasonal changes.
Free option: Request City of Flagstaff's annual Consumer Confidence Report for official city-level data.
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About Flagstaff's Water Supply
Water Utility: City of Flagstaff
Water Source: Upper Lake Mary, groundwater (Surface Water)
Population Served: 76,960
Hardness: 70 PPM (4.1 grains per gallon)
Flagstaff's drinking water comes from surface sources — Upper Lake Mary, groundwater. Surface water requires more extensive treatment than groundwater, including coagulation, filtration, and disinfection. This heavier chlorination is why disinfection byproducts tend to be higher in surface-supplied systems. On the upside, surface sources often deliver softer water than deep aquifers. The system serves 77,000 residents.
Water quality can vary by neighborhood and season. For your exact numbers, request City of Flagstaff's Consumer Confidence Report (CCR) or test your own tap.
ZIP Codes Covered by This Report
This water quality data applies to all areas served by City of Flagstaff in Flagstaff, AZ, including ZIP codes:
85923, 85924, 85928, 85931, 85933, 85936, 85937, 85939, 85942, 86001, 86002, 86003, 86004, 86005, 86011, 86015, 86016, 86017, 86018, 86020, 86023, 86024, 86025, 86028, 86029, 86030, 86031, 86032, 86034, 86035, 86038, 86039, 86042, 86043, 86044, 86045, 86046, 86047, 86052, 86053, 86054, 86336, 86339, 86341, 86351, 86502, 86510, 86544
If your ZIP code is listed above, this report covers your water supply. Water quality may vary slightly by neighborhood.
Compare Flagstaff to Other Arizona Cities
Frequently Asked Questions About Flagstaff Water
Is Flagstaff tap water safe to drink?
Where does Flagstaff's water come from?
Do I need a water softener in Flagstaff?
What is the hardness of Flagstaff water in grains per gallon?
What are disinfection byproducts in Flagstaff's water?
Is chromium-6 in Flagstaff's water?
Can I drink Flagstaff tap water straight from the faucet?
How does Flagstaff compare to the Arizona average?
Data sources: Lead and copper data from EPA Safe Drinking Water Act LCR reporting. Contaminant data from utility-reported testing results. PFAS data from EPA UCMR5 (2023–2025). Hardness from USGS and municipal reports. Data reflects system-level testing results and may not match your specific tap due to neighborhood plumbing, season, or recent utility changes. For your utility's latest results, request their Consumer Confidence Report (CCR). Our methodology. Last updated: 2026-02-24.