The CLR Calcium, Lime and Rust Remover Cleaner is a septic-safe solution designed for dissolving stubborn calcium and lime deposits. Its fast-acting, powerful formula requires no scrubbing and can even tackle surface rust stains. CLR cleaner is phosphate-, bleach-, and ammonia-free, which makes it safe for use on a wide variety of surfaces. However, it is not recommended for use on wood, clothing, marble, terrazzo, natural stone, coloured grout, painted surfaces, plastic laminates, Formica, or aluminum surfaces. After a 2-minute application, simply rinse with cold water to wash away unwanted stains.