Check Local Water Hardness Levels Instantly

Water hardness is the amount of dissolved calcium and magnesium in your water. Water picks these minerals up as it moves through soil and rock. Hardness is measured in grains per gallon (gpg) or milligrams per liter (mg/L), which is the same as parts per million (ppm). Our complete guide to hard water goes deeper.

Groundwater dissolves calcium and magnesium from limestone, chalk and other mineral deposits as it moves through the ground. Regions with more limestone bedrock tend to have harder water, and areas that rely on groundwater tend to be harder than areas served by rivers and lakes. Read more about what causes hard water and why it varies by location.

Yes. The USGS says hardness is not a health concern, but it can be a nuisance: it leaves mineral buildup in plumbing, fixtures and water heaters, and soaps and detergents work less well. That is why many people choose to treat it.

Start with the map for your area's figure. City water customers can also check their water utility's yearly Consumer Confidence Report. For your exact number, use a home test kit or a lab water test, which is the only way to know a private well's hardness. Our guide on how to test water hardness walks through each method.

Both measure hardness. Grains per gallon (gpg) is the unit water softeners are sized in. Parts per million (ppm) is the same as milligrams per liter (mg/L). To convert ppm to gpg, divide by 17.1: 171 ppm is 10 gpg. Our water hardness converter does the math, including German and French degrees.

The EPA says water above 120 mg/L (7 gpg) is generally considered hard and may benefit from softening, and that softeners are often recommended above 180 mg/L (10 gpg). Below that, many homes are fine as they are, and a salt-free conditioner can reduce scale if you still notice it.

A map shows what your area's water utility reports, usually one figure for the whole system. Your own tap can be softer or harder depending on which source supplies your street, the season and your plumbing. For a private well, nearby wells only give a typical range. Test your water before you buy a treatment system.

Often. Wells draw groundwater, which picks up minerals from rock, while many city utilities treat or blend their water before it reaches you. In a national USGS study of about 2,100 private wells (sampled 1991 to 2004), about 60 percent had hard water. A home test is the only way to know a private well.