Hard well water

Hardness

USGS grades water by calcium carbonate content: 0 to 60 mg/L is soft, 61 to 120 moderately hard, 121 to 180 hard, and above 180 very hard.

EPA WaterSense says hard water is not a health concern, but it builds up scale on plumbing and appliances and makes soap hard to lather.

EPA explains that nearly all home softeners use ion exchange, swapping sodium for the calcium and magnesium that cause hardness, and must regenerate periodically.

EPA WaterSense advises installing a softener only where hardness is substantial, for example above 180 mg/L or 10 grains per gallon, and choosing one certified to NSF/ANSI 44.

Texas A&M AgriLife Extension says hard water uses up soap, leaves spots and film, and creates scale in water heaters and pipes.

Texas A&M AgriLife Extension says people on low sodium diets should ask their doctor if sodium is above 20 ppm, which matters because softeners add sodium.

Texas A&M AgriLife Extension says an ion exchange softener can usually remove iron and manganese up to a combined 5 mg/L, but not every softener removes iron, so check the specifications.

Sources: What hardness is; Hard water is not a health risk; Hardness causes scale; Softeners can take out some iron