Where Hard Water Hits Hardest

Hard water is water with high mineral content—especially calcium and magnesium—and its prevalence varies across the U.S., as shown in this heat map.
The harder your water, the more likely it is to leave behind mineral deposits on surfaces like faucets, shower doors, and tile. Over time, this buildup can lead to stubborn limescale stains and reduce the efficiency of appliances that use water.

Mapping the Source of Rust Stains

This heat map highlights regions with higher iron content in the soil, which often translates to higher iron levels in groundwater.
When iron-rich water is used in your home, it can leave reddish-brown rust stains on sinks, tubs, toilets, and even exterior surfaces. Homes in areas with high soil iron may see more frequent or severe staining, especially around water fixtures and outdoor irrigation.