Force the Issue and Clear the Drain

Soap, hair, food particles and cooking grease all help to clog drainage lines.

Occasionally a fixture trap will accumulate a blockage that can be forced clear with a plunger, compressed air or a blow bag.

Most blockages build up inside pipes over an extended period of time, however, and must be cabled, or “snaked,” to be opened. The method you choose will depend on the fixture involved and the size of the drainage line.

Plungers, blow bags and cans of compressed air can all be used to free simple trap clogs. When forcing a trap with any of these, be sure to plug any connecting airways.

When plunging a lavatory, for example, use a wet rag to plug the overflow hole in the basin. When forcing the trap of a two-compartment sink, plug the opposite drain.

After the clog has been forced through the trap and into the drain line, run very hot water through the line to move the clog into the main stack or soil pipe.

If drain water backs up into a tub or shower from another fixture, it probably means that the main sewer line is clogged. If a tub or shower drains slowly or not at all, snake the tub or shower trap and drain line.

To snake a tub, remove the cover plate from the overflow valve and push the cable into the overflow pipe. Do not attempt to cable through the drain opening.

To clean a shower drain, start by removing the drain screen. If the screen is fastened to the drain with screws, remove them and pry the screen up with a knife. If the screen snaps in place, pry it up.

Use a flashlight to look into the trap. If the trap is clogged by soap and hair, you can usually pick the clog out with a wire hook. If the trap is clear but the line is clogged, push the cable through the trap and cable the line to the main stack or nearest soil line.

When you wish to clear the drain line of any fixture with a snake, you first have to remove the trap. Use a pipe wrench or adjustable pliers to loosen the nuts at the top of the trap and at the drain connection near the wall.

With S-traps, loosen the nuts near the floor and at the trap weir. To avoid cracking or breaking a P-trap, hold it firmly and turn the nut with steady, even pressure.

With the trap removed, slide the snake cable into the drain line until you feel resistance. Then tighten the lock nut on the snake housing and slowly crank and push the cable deeper into the line. All bends in the line will offer some resistance, but slow, persistent pushing and cranking will force the cable around bends.

If the cable comes up against a blockage and begins to kink inside the line, back up a foot or so and try again. If you feel steady resistance, keep pushing and cranking. Every three feet or so, stop, pull the snake back a little and then crank forward again.

Try to determine how many feet it is from the trap to the main stack and cable all the way to the stack, even if you break through the clog. When pulling the snake out for the final time, crank in a clockwise direction.

If the clog was caused by a foreign object, such as a piece of sponge or dishcloth, the clockwise coil on the end of the cable will hang onto the object and pull it out as well.

After you have snaked the drain, replace the trap. If the trap washers seem hard and brittle, replace them with new washers. Because much of the debris from the clog will remain in the line, flush with plenty of hot water.

If the fixture drain backs up, plunge it thoroughly and flush the line again.