Looks like blue/green stains on fixtures.
Water, by its nature, wants to dissolve a little of everything it touches. Acid water begins to form as rain comes into contact with pollutants in the atmosphere and forms carbonic acid. Acid water cannot be detected by odor, color, or taste in water but its symptoms are very apparent in the home. If copper plumbing is present, acid water can cause blue/green stains on plumbing fixtures and can dissolve chrome faucets, fittings, and pipes. You are actually seeing part of your copper pipes lying in the bottom of the sink and/or tub. Acid water can also etch china and glass wear and corrode water-using appliances.