Are you standing in water up to your ankle when you take a shower, or are you not able to use the tub because it won't hold water? If so, it's time for some remedial action.
Two Types of Lever-action drain stoppers
There are two types of lever-action drain stoppers in common use (and several drains without trip levers). The pop-up plug is the type that you can see the plug move whenever you operate the lever. The other has a stationary drain cover with holes in it; you do not see anything move when you operate the level. There are some excellent illustrations of various tub drains at the Lowe's website.
The Pop-up Plug
The pop-up plug is a two-piece assembly. First you remove the two large bolts on either side of the lever on the overflow plate. Then pull and wiggle the plate and assembly out by gently turning and twisting the unit.
Next, pull the pop-up plug out of the drain. The overflow plate and the atached assembly will have some sort of spring or cylinder on the end. In this spring is where hair and all sorts of debris collects and blocks the drain.
Once all the debris is cleaned off the spring or plug, you may not need to use a snake or plunger. So run the water and test the drain. If it is still slow, try your plumber's friend, the plunger. Stuff a towel, large sponge or big rag in the overflow drain hole on the wall of the tub and vigorously use the plunger. If that doesn't clear the drain, now you use a snake by inserting the snake into the overflow drain hole.
Once the drain is clear, pour a solution of warm water and Arm and Hammer Washing Soda (found in the laundry section of a grocery store) in the drain to clear out soap scum and oils. The directions for use are on the side of the box.
If hair was the cause of the stoppage, you may want to consider using a drain protector to catch the hair before it gets in the drain. Protectors for pop-up type drains are available online and in brick and mortar stores.
When you go to reassemble the pop-up type drain, the secret is to make sure to insert the pop-up plug and rocker arm into the drain opening FIRST with the curved section of the rocker arm down before you insert the overflow plate and assembly. This is a critical step. If you insert the plug in after replacing the overflow plate assembly, the rocker arm can get stuck in the spring. The spring must sit on top of the rocker arm.
I've been in hotel rooms where I found the tub drain would not close all the way or where the plug is sitting on the edge of the tub. I can only speculate, but I think what happens is the tub drain is slow and a hotel guest has pulled the plug out of the drain hoping the water would drain faster. Then housekeeping simply pushes the plug back into the drain; this usually doesn't work.
Once the plate and assembly are back in place, replace the bolts. Make sure to get the overflow plate bolts back in snugly, otherwise water can leak into the wall cavity if the water level rises above the overflow plate.
The Stationary Drain Cover
The other type of tub drain that has the stationary drain cover is much better at preventing hair and debris from getting into the drain. Most of the hair and debris collects on top of the drain cover, so you can pick it up and discard in the trash. You still remove the assembly by removing the overflow plate and pull the assembly up and out.
When I had a new tub installed a few years ago, the plumber installed the drain with the pop-up when I had my back turned. I asked him to change it to the stationary drain cover type, and he made some noises about most people preferred the pop-up type, the stationary type was difficult to find, etc.
I insisted, and he managed to find one. I contend that the people he thought preferred the pop-up type probably didn't realize they had a choice.
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