This morning my husband was showering and water started coming out full of black particles. Seems to be in cold water mostly. It does not smell at all. We have had our well for 15 years and have not had a problem. Any idea what could cause this?

It could be the impeller's breaking down. Tell me more about those
Black particles. Are they hard or soft? Any color come off when you rub them? Are the particles plastic, metal or rubber?
More details please. Tom