An overwhelming 85 percent of the USA has hard water, so the likelihood that you live in state or city with hard water is high. The following hard water map illustrates the varying zones of hardness across the USA.

Las Vegas, NV: Water is carried into Lake Mead from the mineral-dense Colorado River resulting in 16+ gpg of hard water for homes in the Las Vegas area. Phoenix, AZ: Water is supplied to this area from both mineral dense groundwater and Lake Mead in Nevada, picking up additional minerals as it travels into the metro area and resulting in a 16 gpg level. San Antonio, TX: Rainwater runs through soil and rock before it moves into the natural aquifers where water is collected, resulting in a large mineral collection of 15-20 gpg. Minneapolis, MN: Manmade contaminants and mineral-heavy water from the Mississippi River, the area’s main water source, produce a 15+ gpg level for the Twin Cities. Indianapolis, IN: Water in this area is supplied from surface and groundwater creeks containing calcium, magnesium and iron salts — producing a hard water rating of up to 20 gpg. Tampa, FL: The water hardness fluctuates but can get up to 17 gpg during the dry season when there is less fresh rainwater to dilute the supply.

Top Cities with Hard Water

Indianapolis, IN

Las Vegas, NV

Minneapolis, MN

Phoenix, AZ

San Antonio, TX

Tampa, FL

Did You Know?

Ancient seabeds covered most of the US, which left high concentrations of limestone in the “hard” to “extremely hard” regions.