The Water Hardness Scale – How Hard is Your Water?

Illustration of a water drop with a large green check mark on itMost people recognize what hard water feels like – it dries quickly, doesn’t produce a good soap lather, and leaves your hair looking dull. Many people also recognize the signs of hard water in a home – spotting on dishes, soap scum, and scaling on faucets. But hard water isn’t just a matter of opinion. The concentration of dissolved minerals like calcium and magnesium can be tested, and the results plotted on the water hardness scale.

Water hardness is most often expressed in grains per gallon (gpg), but you may also see it as parts per million (ppm). The United States Geological Survey uses the following scale to classify the level of water hardness:

Grains Per Gallon Water Hardness
0 – 1 Soft
1 – 3.5 Slightly hard
3.5 – 7.0 Moderately hard
7.0 – 10.5 Hard
Above 10.5 Very hard


Hach SofChek Water Quality Test Strips for Total Hardness, 0-425 mg/L

Hach SofChek Water Quality Test Strips, available at

You can test your water hardness using a home testing products such as Sofchek test strips. Water softener companies typically also perform free testing as part of a consultation. However, be prepared to be on the receiving end of a sales pitch if your water tests hard. One good way to find out if a water company is trustworthy is to test your water before the consultation, to see if they misrepresent how hard your water is.

Some water softener salespeople may try to convince you that you need a water softener if you have any amount of hardness in your water. However, unless you have at least 7 grains per gallon (the hard classification on the water hardness scale), a water softener probably isn’t a must-have. You may get some benefit from it, but the system isn’t likely to pay for itself in terms of increased water heater efficiency and other tangible improvements.

On the other hand, if you’re thinking about getting a salt free water softener, you should make sure that your water isn’t too hard. For very hard water, these saltless systems are generally not recommended. Instead, go for a conventional ion-exchange softener if you can.

If you do get a water softener, it’s a good idea to test your water before and after installation to make sure the system is working as advertised. Again, using water hardness test strips or a similar product at home is the best way to verify that you’re getting what you paid for. You don’t have to take anybody else’s word for it – you can see for yourself.