What is the cause of your discoloration on sinks, tubs and toilets?
If the stains or water are blue-green in color, then most likely, corrosion of copper is occurring within the household plumbing. Stains that are various shades of yellow, tan, brown, black, orange, or red can indicate the presence of metals other than copper.
Two other metals that are typically to blame for staining are iron and manganese. While these minerals serve as essential nutrients for your body, they aren’t so kind to plumbing fixtures or appliances. Reddish and yellow-tan discoloration is often caused by iron, while black or dark brown discoloration points to manganese. Due to their similarities they are generally treated in much the same way.
Discoloration usually results from the exposure of these metals to oxygen, known as oxidation. In your plumbing, water often has limited exposure to oxygen, keeping any soluble iron or manganese in solution. Once these metals come out of a faucet and are exposed to the air, oxidation occurs and chemical reactions may cause them to form a substance that creates visible staining.