How to Unclog a Drain

To clear a drain clog, start by plunging , then use a snake or disassemble the P-trap. The best use of chemicals is for drain maintenance.

The interiors of drain pipes are really smooth; stuff isn't supposed to stick to them, but it does, and the reason usually has a lot to do with the type of stuff you put in the drain. Grease, soap and other thick materials form residues on the pipe that gradually build. Hair and vegetable fibers -- which can lodge on sink strainer or P-trap mechanism, hasten this process by fishing these clogging materials out of the water. A plunger usually gets water flowing again once it has stopped, but you may need a physical cleaning -- or chemicals -- to really solve the problem.

Proper Plunging Procedure

A sink plunger is the first line of attack against a drain clog, but you need to use it properly to derive the maximum benefit from using it.

    Use the right plunger.

  1. A sink plunger, which is what you need for sinks, bathtub and shower drains, is dome-shaped. It isn't the accordion-shaped or fluted implement you use to plunge your toilet.

  2. Block the drain outlets.

  3. If you want the full force of the plunger to push against the clog, you need to prevent air from escaping from the drain. Put duct tape over the overflow holes in the sink or around the lever mechanism in the bathtub.

  4. Get ready.

  5. Fill the sink, bathtub or shower pan with an inch of water. Immerse the plunger in the water then tilt it slightly to allow air to escape and to fill the dome with water. This ensures that you're plunging with incompressible water -- not compressible air.

  6. Go.

  7. Pump vigorously several times, then lift the plunger to see if water is draining. If not, plunge again. Keep going until water starts to drain -- in 99 percent of cases, it will.

Snaking a Drain

  • When plunging doesn't improve water flow, try a sink auger. As opposed to a toilet or sewer auger, a sink auger is relatively short, and the cable is flexible enough to curve inside the P-trap.

    1. Remove the sink strainer or pop-up stopper mechanism.

    2. Insert the head of the auger and push it into the drain, unwinding the cable as you do, until it won't go any farther.

    3. Keep pushing while you crank the auger handle until you feel the head move forward. At this point, you may want to pull it out of the drain and remove debris before continuing. Repeat the process until water drains freely.

    Using Chemicals

  • Chemicals aren't the best solution for clearing a clogged drain, and harsh drain cleaners that contain sodium hydroxide can actually be hazardous, especially if you're on a septic system. Sodium hydroxide produces heat in reaction with water, and the resulting corrosive solution can damage the pipes and create a hazard for anyone disassembling the drain to clean it mechanically. Sulfuric acid-based cleaners aren't any safer, but those containing citric or phosphoric acid may be, although there's no way for any of these chemicals to get to a clog if the water isn't flowing.

  • The best use of chemicals is to disinfect and deodorize -- vinegar and baking soda work well for this -- or to prevent clogs -- and enzyme-based drains cleaners do this well. Use citric or phosphoric acid-based cleaners to clear slow-moving drains -- not stopped ones.

  • Mechanical Cleaning

  • If the drain is clogged because of a build-up of hair, remove the hair with a plastic drain-cleaning tool. Insert the tool into the drain opening, hook the hair and pull it out. To clear hair out of the reach of this tool, it's best to disassemble the P-trap, take it outside and wash it out with a garden hose.

  • Check the Vents

  • If your drains are chronically clogged, there's a good chance the plumbing vents are blocked. If the clogs occur in summer, it may be because leaves or a bird's nest are blocking the vent opening. If you don't find anything there, spray water into the vents with a garden hose and use a sewer auger to clear the blockage if the water overflows.

  • In winter, the problem could be icing over of the vent stack. Go in the attic with a hair dryer to melt the ice in the section of the vent nearest the roof and consider installing a wider vent stack in the spring.