What Every Water Hardness Level Means

Every hardness from 1 to 50 grains per gallon in both grains and milligrams per liter, its USGS classification, what it does to appliances, and the softener size it points at.

Every page below is computed rather than written, from the same formulas the matching calculator uses, so a figure on a chart page and the same figure in the calculator cannot disagree. Each one carries its working, the basis of every number it prints, and equipment chosen by those numbers rather than from a general list.

• What does 1 grains per gallon mean? 1 grains per gallon is 17 mg/L, classified as soft. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 2 grains per gallon mean? 2 grains per gallon is 34 mg/L, classified as slightly hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 3 grains per gallon mean? 3 grains per gallon is 51 mg/L, classified as slightly hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 4 grains per gallon mean? 4 grains per gallon is 68 mg/L, classified as moderately hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 5 grains per gallon mean? 5 grains per gallon is 86 mg/L, classified as moderately hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 6 grains per gallon mean? 6 grains per gallon is 103 mg/L, classified as moderately hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 7 grains per gallon mean? 7 grains per gallon is 120 mg/L, classified as moderately hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 8 grains per gallon mean? 8 grains per gallon is 137 mg/L, classified as hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 9 grains per gallon mean? 9 grains per gallon is 154 mg/L, classified as hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 10 grains per gallon mean? 10 grains per gallon is 171 mg/L, classified as hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 11 grains per gallon mean? 11 grains per gallon is 188 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 12 grains per gallon mean? 12 grains per gallon is 205 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 13 grains per gallon mean? 13 grains per gallon is 222 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 14 grains per gallon mean? 14 grains per gallon is 239 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 15 grains per gallon mean? 15 grains per gallon is 257 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 16 grains per gallon mean? 16 grains per gallon is 274 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 17 grains per gallon mean? 17 grains per gallon is 291 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 18 grains per gallon mean? 18 grains per gallon is 308 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 19 grains per gallon mean? 19 grains per gallon is 325 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 20 grains per gallon mean? 20 grains per gallon is 342 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 21 grains per gallon mean? 21 grains per gallon is 359 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 22 grains per gallon mean? 22 grains per gallon is 376 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 23 grains per gallon mean? 23 grains per gallon is 393 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 24 grains per gallon mean? 24 grains per gallon is 410 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 25 grains per gallon mean? 25 grains per gallon is 428 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 26 grains per gallon mean? 26 grains per gallon is 445 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 27 grains per gallon mean? 27 grains per gallon is 462 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 28 grains per gallon mean? 28 grains per gallon is 479 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 29 grains per gallon mean? 29 grains per gallon is 496 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 30 grains per gallon mean? 30 grains per gallon is 513 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 32 grains per gallon mean? 32 grains per gallon is 547 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 35 grains per gallon mean? 35 grains per gallon is 599 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 40 grains per gallon mean? 40 grains per gallon is 684 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 45 grains per gallon mean? 45 grains per gallon is 770 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.
• What does 50 grains per gallon mean? 50 grains per gallon is 855 mg/L, classified as very hard. What it does to appliances, whether it needs treating, and the softener size it points at.

Researched, not professional advice. Every figure on these pages is labeled as a published standard, a trade rule of thumb, or something that can only come off your own water test. Where a published figure does not exist we say so rather than estimating one. Test your water before you buy equipment: on city water start with the Consumer Confidence Report your utility publishes each year, and on a private well only a certified laboratory test tells you what you have. Bacteria, nitrate, lead, arsenic and PFAS are not do it yourself topics and need a laboratory and usually a licensed professional.