Hardness is measured in "grains per gallon" (GPG)—and no, we’re not talking about oatmeal. One grain is about the size of a single grain of table salt. Most city water runs between 3 and 10 grains per gallon. Well water? That can jump to 20, 50, or even 100 grains.
If you’ve ever seen that milky-white residue on your shower glass, that’s about 10 or 15 grains of dissolved rock. Your softener is basically a tiny, quiet mining operation that pulls those minerals out of your water. Pretty wild, right?
How to find your magic number
You can buy a water test kit at the hardware store for like ten bucks. Or, call your local water company—they usually tell you the hardness for free. Once you know your grains, you dial that number into your softener. That’s it. Boom. You’re a water wizard.
But here’s a friendly tip: slightly under-set it if you’re on a well. Well water can fluctuate like a mood ring. If you set it exactly at 20 grains, and next month it’s 22, you’ll notice. A tiny buffer keeps your water consistently soft without wasting salt.
