Edition: U.S. / Global


Published: November 29, 1987

POP-UP drains in bathroom basins may seem mysterious, but actually they are simple to repair. Knowing how they operate is useful.

The familiar knob that causes the drain plug to glide up or down is really the upper end of a long vertical rod, called the lift rod, shown in the illustration. The rod passes through a hole in the rear of the basin, then connects underneath with other parts of a linkage system, also shown.

The lower end of the lift rod passes through an adjustable connection at one end of another vertical rod, called the clevis. The clevis is flat, and contains holes drilled through it at intervals along its length.

A setscrew holds the clevis to the lift rod. By loosening the screw, the clevis may be slid up or down the lift rod; then, by tightening the screw, the clevis may be locked in place at any height.

The end of a horizontal rod, called the pivot rod, passes through one of the holes in the lower portion of the clevis. This rod is held in place by a spring clip, a folded piece of thin metal with a hole drilled through each side. Pinching the folded halves together loosens the clip and allows the pivot rod to be slid in and out. Permitting the halves to spring apart prevents the rod from moving.

The other end of the pivot rod enters a segment of pipe just below the underside of the basin. As the illustration shows, a ball, usually made of plastic, is threaded onto the rod a short distance from the end, and is enclosed in a projecting portion of the segment.

A circular retaining nut fastens over the open end of the projecting portion, sealing the ball and rod inside. Beyond the ball, the remainder of the pivot rod extends into the drain pipe. There, directly beneath the basin drain opening, it is joined to the bottom of the drain plug.

Pushing or pulling on the lift rod causes the pivot rod to tilt (the ball acts as the fulcrum of a lever), which in turn pushes the drain plug upward, or draws it downward into the drain opening.

When the drain fails to operate properly, either one or more of the connections linking the parts has loosened or broken, or else debris has accumulated on or below the drain plug.

Check for debris first. To do this, remove the drain plug from the drain opening. Most plugs merely lift out, but some must be rotated in one direction or the other while twisting, to free the end of the pivot rod from a slot cut in the bottom of the plug.

A few types of plugs can be removed only by dismantling the pivot rod assembly, a simple procedure described further on.

In any case, once the plug is removed, clean it thoroughly and then clear the drain as well, by swabbing it with a long-handled bottle-cleaning brush.

If the drain is seriously clogged, now might be a good time to remove the trap, the U-shaped section of pipe below the drain, and clean it. However, before doing so, be sure you have replacement washers on hand to insert beneath the slip nuts, which connect the trap to the plumbing on each side.

Reinsert the clean drain plug by reversing whatever procedure you used to remove it. Then test your handiwork by pulling up on the lift rod to seal the plug in the drain and running some water into the basin. If the water remains in the basin until you open the drain and let it out, your work is done.

However, if the drain still leaks, or if there are other problems, you must inspect and readjust the lift rod and pivot rod connections.

Begin by squeezing yourself beneath the basin, taking with you a flashlight and a pair of pliers, and perhaps a can of penetrating oil such as Liquid Wrench or WD-40.

Locate the setscrew that fastens the lift rod to the clevis. Loosen the screw by turning it counterclockwise, using the pliers, until the rod slides freely. If the screw does not turn easily, be careful not to destroy it by exerting too much pressure. Instead, lubricate the screw with penetrating oil. Wait an hour or so, then try again. Should the screw break off, it is easily replaced at a hardware store.

Press the drain plug by hand firmly into the drain opening so that it seals. Then, from underneath the basin, push the lift rod upward as far as possible without separating it from the clevis. Leaving approximately one-quarter inch of the rod extending below the clevis connection, retighten the setscrew to lock the two pieces of the drain linkage together. Then test the operation of the lift rod. If it sticks or is difficult to slide up and down smoothly, you must readjust the pivot rod.

To do this, squeeze the spring clip that holds the rod to the clevis, using either your fingers or the pliers, then slide the rod completely free. Raise the clip to the next higher hole, then reinsert the pivot rod.

Try the lift rod again. If the results are still unsatisfactory, readjust the setscrew again.

If you discover leakage where the pivot rod enters the drain pipe, or if you must dismantle the assembly to remove the drain plug, use a wrench to loosen the retaining nut that houses the pivot ball.

With the nut off, you can withdraw the pivot rod and ball from the pipe segment, releasing the drain plug if necessary, or permitting inspection of the components. Clean the ball if it is dirty and lubricate it with a dab of petroleum jelly or silicone grease.

Reinstall the pivot rod, wrap Teflon plumber's tape around the threads of the projecting pipe segment, then tighten the retaining nut securely to prevent leaking.