Why Liquid Drain Cleaners Are Not Ideal Clog Relievers? A slow or a clogged drain is a common problem that can occur anytime. Calling for a plumber might not be your immediate decision; so what do you do? You try using a commercial liquid drain cleaner to see if it works out by chance and negates the chance of calling a plumber. Although such drain cleaners are cheap and require minimum effort, it is a strict nono if you want your drain to run smoothly without further troubles. Here are the reasons why such drain cleaners must not be used & the suitable alternatives for drain clogs or slow drains: