Phoenix, AZ
285 PPM - Very Hard. Colorado River and Salt River sources. One of the highest hardness levels of any major US city.
Data sources: All hardness figures are sourced from official city Consumer Confidence Reports (CCRs) and USGS water quality data. CCRs are published annually by every US municipality. We link to the official city report for every guide.
Hardness Levels at a Glance
| Classification | PPM (mg/L) | GPG | What It Means |
|---|---|---|---|
| Soft | 0 to 60 | 0 to 3.5 | No treatment needed |
| Moderately Hard | 61 to 120 | 3.5 to 7 | Shower filter is a reasonable first step |
| Hard | 121 to 180 | 7 to 10.5 | Shower filter or water softener recommended |
| Very Hard | 181+ | 10.5+ | Water softener strongly recommended |
Browse City Guides
Southwest and Mountain West (Hardest Water in the US)
Los Angeles, CA
125 to 340 PPM - Hard to Very Hard depending on district and source water mix.
Dallas, TX
140 to 200 PPM - Hard. Multiple reservoir sources. Hardness varies by district and season.
Chicago, IL
130 to 160 PPM - Hard. Lake Michigan source, treated but still significantly hard.
South and Southeast
Houston, TX
100 to 200 PPM - Moderately Hard to Hard. Surface water from Lake Conroe and Lake Livingston.
San Antonio, TX
357 PPM - Extremely Hard. Edward Aquifer source. Among the hardest major city water supplies in the US.
Miami, FL
120 to 200 PPM - Hard. Biscayne Aquifer source. Florida's limestone geology drives high hardness statewide.
Tampa, FL
150 to 250 PPM - Hard to Very Hard. Floridan Aquifer. One of the hardest water supplies in Florida.
Pacific Northwest (Softest Water)
Seattle, WA
18 to 35 PPM - Soft. Cedar River and South Fork Tolt River mountain sources. One of the softest major city water supplies in the US.
Portland, OR
15 to 60 PPM - Soft. Bull Run Watershed source. Consistently very soft, naturally low mineral content.