Liquid drain cleaners are one of the worst “quick fixes” you can use in your home. Half of the time they don’t even work, because they’re meant to be used on very specific kinds of clogs. But more importantly, they can do real damage to your plumbing system and the environment. Instead of wasting your money on toxic drain chemicals, invest in a simple hand crank drain snake. Homeowners also forget that you can use your trusty plunger on shower, sink, and floor drains, too. While some plumbers ignore the side effects of liquid drain cleaners, or even encourage them, we believe it’s our responsibility to put chemical drain cleaners to rest for good.
Source: Why Liquid Drain Cleaners Suck