I recently had the unpleasant experience of a 99% clogged kitchen sink. This was a slow build-up of everyday dumping in small food bits into the drain, such as washing out a cat food can before tossing into the trash. I don't have a garbage disposal so it slowly became a problem that couldn't be ignored any longer. I tried non-commercial solutions such as pouring boiling water in the drain - no help at all plus it was frightening to handle the boiling water. So I went to my local Lowe's and had a nice selection to choose from. I picked up the 42 fl. oz. container of Liquid-Plumber Industrial Strength Gel Clog Remover because it was moderately priced. I paid $4.78 before tax. I followed the easy directions which were to pour 1/2 of the bottle slowly down the drain and allow the solution to sit for 15 minutes. Flush with hot water and you're good to go. I was lucky - my drain was not completely stopped up so I didn't have standing water. It is draining completely and fast and I still have 1/2 bottle for next time. So I unstopped my drain for approximately $2.89 - what a deal. Be sure and always read the DANGER information. Especially keep out of reach of children warnings.