Phoenix, AZ water hardness

Name: Phoenix, AZ water hardness as published by City of Phoenix Water Services Department
Creator: City of Phoenix Water Services Department
License: https://www.usa.gov/government-works

City of Phoenix Water Services Department publishes a hardness range of 172 to 302 mg/L for its system, in its City of Phoenix 2025 Water Quality Report. On the USGS scale that is very hard water.

City of Phoenix Water Services Department published a range of 172 to 302 mg/L, shown as the bar. The plotted point is the midpoint of the published range (no average is published). Classification bands from the USGS Water Science School.

The published figure, exactly as it appears

This is the hardness line transcribed from the source, with nothing added:

Total Hardness ppm; grains/gallon NA 172 - 302 / 10 - 17.6
City of Phoenix Water Services Department, City of Phoenix 2025 Water Quality Report

Units as published: ppm and grains/gallon. What kind of figure it is: a range with no average. Retrieved 2026-10-16.

Phoenix hardness in mg/L and grains per gallon

Water-quality reports use mg/L (identical to ppm). Softener instructions and plumbing specifications use grains per gallon. Both are below. Where a figure is our arithmetic rather than the utility's own number, it says so.

Figure	mg/L (ppm)	Grains per gallon	Whose number
Low end of published range	172	10	mg/L published, gpg is our conversion
High end of published range	302	17.6	mg/L published, gpg is our conversion
Plotted on the scale above	237	13.9	midpoint of the published range (no average is published); the gpg here is our conversion at 17.1, so it can differ slightly from a utility’s own rounded gpg figure

The conversion, both ways: gpg = mg/L ÷ 17.1 and mg/L = gpg × 17.1. Worked for this system: 237 ÷ 17.1 = 13.9 gpg. The converter does °dH and °f as well, and why the factor is 17.1 explains where the number comes from.

What this figure does not tell you

Service area and source water

Utility	City of Phoenix Water Services Department
Service area as published	The primary Phoenix water system, serving approximately 1.7 million residents in 2025 per the report. The Phoenix-Anthem system was deactivated in August 2022 and the Phoenix-Hedgepeth Hills system in autumn 2024; both have their own final reports.
Source water	Rivers, lakes, streams, springs and wells; the primary untreated surface water sources are the Salt, Verde and Colorado rivers.

Provenance of every number on this page

Source document	City of Phoenix 2025 Water Quality Report
Source URL	https://www.phoenix.gov/content/dam/phoenix/waterservicessite/documents/wsdprimarywqr.pdf
Published by	City of Phoenix Water Services Department
Report year	2025
Year note	Hardness appears in the table headed '2025 AESTHETIC WATER QUALITY ANALYSIS FROM DISTRIBUTION SYSTEM & SECONDARY DRINKING WATER GUIDELINES'.
Retrieved	2026-10-16
Classification bands	USGS Water Science School, retrieved 2026-10-16

Notes the report forces on this page

The report publishes a range only, with 'NA' in the average column, so no system average is shown on this site.
The report notes that taste, odour and hardness are not regulated under drinking water health standards.

If you are sizing a softener for Phoenix water

At 13.9 gpg, the sizing arithmetic starts from your household's water use, not from the hardness alone. The calculator below is pre-filled with this system's figure and every other input is an editable assumption.

Whether a softener is worth installing at this hardness is a judgement, not arithmetic, and it is not one this site makes for you. Nothing here has been tested by the author.

Where Phoenix sits against other verified systems

Soft Soft 0–60

Moderately hard Moderate 61–120

Hard Hard 121–180

Very hard Very hard 181+

Portland, OR 9 mg/L 0.5 gpg Soft
Boston, MA 16 mg/L 1 gpg Soft
Manchester, NH 17.9 mg/L 1 gpg Soft
New York, NY 32 mg/L 2 gpg Soft
Austin, TX 93 mg/L 5.4 gpg Moderately hard
Denver, CO 105 mg/L 6.1 gpg Moderately hard
Phoenix, AZ 237 mg/L 13.9 gpg Very hard
Las Vegas, NV 280 mg/L 16 gpg Very hard
San Antonio, TX 299.3 mg/L 17.5 gpg Very hard
Indianapolis, IN 317 mg/L 19 gpg Very hard

mg/L as calcium carbonate. Each classification band is drawn the same width, so the axis is not linear in mg/L.

Phoenix, AZ is the highlighted row. Every other system on this chart has its own page with its own published figure and report date. Grains per gallon are the utility's own figure where it published one, and our conversion at 17.1 mg/L per grain where it did not.

Systems with similar published hardness

Las Vegas, NV Las Vegas Valley Water District, 280 mg/L (16.4 gpg)
San Antonio, TX San Antonio Water System (SAWS), 299.3 mg/L (17.5 gpg)
Indianapolis, IN Citizens Energy Group (Indianapolis), 317 mg/L (18.5 gpg)
Denver, CO Denver Water, 105 mg/L (6.1 gpg)

All 10 verified systems How to find hardness in your own utility's report If you are on a well instead