NOTE: THIS IS AN ARCHIVED VERSION OF A STORY THAT APPEARED IN THE NOVEMBER 2006 ISSUE OF CONSUMER REPORTS. PRODUCTS MIGHT HAVE CHANGED SINCE WE REVIEWED THEM, SO USE THE RATINGS AS ONLY A GUIDE.

Chemical drain cleaners are among the most dangerous household products—hardly a shocker, since these lye-based formulas are meant to dissolve plugs of grease, soap, hair, and ground-up food. Yet most don’t clear undersink clogs as well as old-fashioned mechanical methods, including the humble plunger.

Another surprise: Chemical products labeled “heavy duty” or “professional strength” often proved less effective than their regular-strength counterparts in clearing kitchen clogs made of grease and food, and bathroom clogs of soap, toothpaste, and hair. And two foaming chemicals, from Drano and Liquid-Plumr, tanked altogether in our tests. To read the rest of the story, including information on how to choose a drain cleaner, types, safety, and ratings, download this PDF:

Consumer Reports Drain Cleaners