I found a crusty white powder forming on my water shutoff valves under the sink. Should I be worried?

gritty to the touch.
In some cases, the white powder might also contain traces of other minerals such as magnesium, depending on the specific composition of your local water supply. The presence of these minerals can vary significantly, with hardness levels ranging from 60 milligrams per liter (mg/L) in softer water areas to over 180 mg/L in regions with very hard water.
2. How To Tell If It’s Just Harmless Mineral Buildup
To determine if the white powder is simply harmless mineral buildup, consider the location and extent