Liquid Plumr cuts through standing water to clear fully-blocked drains, prevents clogs with regular monthly use and protects pipes. This powerful system removes hair, gunk, grease and soap scum whether you have a total blockage or a slow-running drain. It works in the bathtub, shower, bathroom sink, kitchen sink and garbage disposal, and when used monthly prevents buildup and stops clogs from forming. This drain cleaner is safe for all septic systems, garbage disposals and pipes, including PVC, plastic, metal and old pipes. Do not use with a plunger, in toilets or with ammonia, toilet bowl cleaners, or non-Liquid-Plumr clog removers (to avoid hazardous gas). It contains biodegradable surfactants and no phosphorous. Excessive heat or cold may cause Liquid-Plumr to form clumps, but this should not affect performance.