All Cities
Local Water DataMaricopa County

RO Membrane Selection for Phoenix, AZ Water

City of Phoenix Water Services Department
PWS ID: AZ0407025
2025 water quality report

What's in Phoenix's Water

Reported values from City of Phoenix Water Services Department's 2025 water quality data. Feed water chemistry drives membrane choice, operating pressure, and cleaning frequency.

Source water

97-99% surface water — Salt, Verde and Colorado rivers (SRP canals and the Central Arizona Project aqueduct, with Agua Fria water via Lake Pleasant) — treated at five plants; ~2% from about 20 city groundwater wells

Hardness

302 mg/L as CaCO3

Very hard — high scaling risk — expect antiscalant dosing, conservative recovery, and a regular cleaning schedule

Alkalinity (range)121-167 ppm
Arsenic7 ppb
Arsenic (range)ND-8.5 ppb
Arsenic notehighest running annual average vs the 10 ppb MCL
Barium (range)0.007-0.13 ppm
Chlorine0.84 ppm
Chlorine dioxide (range)ND-540 ppb
Chlorite0.3 ppm
Chromium (range)ND-87 ppb
Combined radium (range)ND-0.8 pCi/L
Copper 90th0.3 ppm
Fluoride (range)0.3-1.1 ppm
Gross alpha (range)ND-1.6 pCi/L
HAA517 ppb
HAA5 (range)0.6-26 ppb
Hardness (range)172-302 ppm
Hardness note10-17.6 grains per gallon
Lead (range)ND-41.8 ppb
Lead 90th3 ppb
Lead note2 of 56 sampled taps over the action level (2024 sampling)
Lithium70.2 ppb
Lithium (range)22.2-160 ppb
Nitrate3.8 ppm
Nitrate (range)ND-4.5 ppm
Pfba0.005 ppb
Pfbs0.011 ppb
PH (range)6.6-8.8
Selenium (range)ND-2.2 ppb
Sodium (range)91-183 ppm
TDS (range)464-716 ppm
TTHM49 ppb
TTHM (range)4-68 ppb
Uranium (range)ND-4.6 ppb

Our Recommendation for Phoenix

Phoenix publishes what most utilities hide, and it's the hardest big-city water we've profiled: hardness 172-302 mg/L (10-17.6 grains per gallon) and TDS running 464-716 — past the 500 mg/L federal guideline at the top of the range. Add arsenic averaging 7 ppb against a 10 ppb limit, chromium samples to 87 vs a 100 MCL, and lithium to 160 ppb, and this is textbook feed water for a brackish NanoH2O (formerly LG) BW 400 R G2 with a real antiscalant program — the same scaling math as South Texas, at metropolitan scale.

Membranes Matched to This Water

The Industry Workhorse

NanoH2O (LG) BW 400 R G2

  • 99.8% salt rejection
  • 11,500 GPD · 225 psi
  • 400 ft² active area
View membrane

Running RO on Phoenix water?

Send us your system size and feed water details — we'll spec the right membrane for your operation and quote same-day shipping.

Data Source

Water quality values on this page are taken from City of Phoenix Water Services Department's 2025 published water quality report (PWS ID AZ0407025). Values are utility-wide averages; water at a specific site can vary. For membrane selection on a critical system, test your actual feed water.

View the official report