Sodium hypochlorite
Liquid Drano was introduced in response to Clorox's purchase of Liquid-Plumr in 1969. Originally, it was simply a liquid lye (sodium hydroxide). In the late 1970s, the product was reformulated as a combination of liquid lye and sodium hypochlorite. Sodium hypochlorite is used in low (5%) concentration as laundry bleach and in higher concentrations as a swimming pool disinfectant.