Check Your Water Hardness
Free water hardness data for every zip code in the US. Powered by EPA and USGS data covering 31,389 zip codes and 48,068 water systems.
What Is Water Hardness?
Water hardness measures the dissolved mineral content in your water, primarily calcium and magnesium. It's measured in parts per million (PPM) or grains per gallon (GPG). Hard water is a common issue across much of the United States, affecting everything from your plumbing and appliances to your skin and hair.
Scale Buildup
Hard water leaves mineral deposits in pipes, water heaters, and fixtures, reducing efficiency and lifespan.
Skin & Hair
Minerals in hard water can leave skin feeling dry and hair looking dull. A water softener or shower filter can help.
Appliance Damage
Dishwashers, washing machines, and water heaters work harder and wear out faster with hard water.
Understand Your Water
Water Hardness Scale: What PPM Means & When It Matters
Understand the USGS hardness scale, convert between PPM and GPG, and see real city examples at every hardness level.
10 min readHow to Test Water Hardness at Home (Free + DIY + Kit Methods)
From free online lookups to test strips and lab testing - every way to find out how hard your water is.
8 min readDo You Need a Water Softener? (Based on Your Water Hardness)
A data-driven guide to help you decide if a water softener is worth the investment based on your actual water hardness level.
10 min readBest Water Softeners 2026: Top Picks for Every Budget
We compared salt-based, salt-free, and portable water softeners. Here are our top picks based on water hardness level, home size, and budget.
12 min read