Hard water in Phoenix

What the utility reports

Phoenix's 2025 Water Quality Report gives total hardness of 172 to 302 ppm, or 10 to 17.6 grains per gallon.

Source: City of Phoenix 2025 Water Quality Report

How to read the numbers

Tucson Water classifies hardness (mg/L as calcium carbonate) as 0–60 soft, 60–120 moderate, 120–180 hard and 180+ very hard (Tucson Water). To convert mg/L (ppm) to grains per gallon, divide by 17.1 (same source).

Hardness varies by neighborhood and water source, so test your own tap before programming a softener (how to set it).

What hard water does

Phoenix's water report notes that hard water can cause scaling in pipes and water heaters and on fixtures (City of Phoenix). See 7 signs you need a softener, or compare softener vs. RO.