What Is Hard Water?

Hard water is water that has a high amount of natural, nontoxic minerals—mainly calcium and magnesium. It’s called “hard” because it makes it harder for soap to lather and can leave mineral spots on dishes or buildup on faucets and showerheads.

Hard water is very common in California and is not a health concern. In 2024, CVWD’s water hardness ranged from 130 to 390 mg/L, with an average of 341 mg/L—this is considered hard.

If you're thinking about installing a water softener, we recommend speaking with a licensed plumber or water treatment specialist.

Why are there white spots on my dishes?

The white spots often seen on dishes or inside ice cubes are caused by minerals—mainly calcium and magnesium—that naturally occur in hard water. Ice cubes freeze from the outside, so the center of the cube is the last to freeze. This pushes the minerals toward the center of the cube, where they become more concentrated. When the freezing is complete, these minerals can appear as a white, cloudy spot in the middle of the ice.

These mineral deposits, called precipitates, are not harmful. They can also show up as white spots on dishes after water evaporates. Some commercial ice makers remove this buildup, but in home freezers, it's a normal result of using hard water.