Aqua Safe Descaler is safe on steel, stainless steel, iron, brass, copper, plastic, rubber, and other materials found in most water cooled, heated, or operated equipment. Ideal for water heat exchangers, tankless hot water heaters, coolers, pumps, boilers, compressors, condensors, extruders, molds, cooling towers, furnaces, water piping systems and other water side heat exchange surfaces.