The Tub Wouldn’t Hold Water Until I Fixed This One Thing Behind the Overflow
I kept thinking the problem was at the drain opening. The tub wouldn’t stay full, even though nothing looked cracked or damaged. I would flip the lever, start filling the tub, and watch the water level slowly drop. It wasn’t draining fast, but it wasn’t sealing either.
The strainer looked fine. The lever moved. Nothing seemed broken.
The issue wasn’t in the drain at all.
It was inside the overflow assembly.
What I Noticed After Removing the Drain and Overflow Plate
I started by removing the old strainer from the drain. It came out easily, and I replaced it with a new matching piece. The installation was simple and everything sat flush. I expected that to solve the issue.
It didn’t.
So I moved to the overflow plate and pulled the triplever assembly out. Once the faceplate came off and the plunger and rod slid free, the problem became clear. The linkage had wear, and the connection at the cotter pin had loosened over time. The mechanism still moved when I flipped the lever, but it didn’t pull the plunger into position with enough force to seal the drain.
From the outside, it looked functional. Inside, it was underperforming.
The Cotter Pin and Linkage Were the Real Problem
The triplever controls a plunger inside the overflow tube. When you move the lever, it shifts the rod assembly, which either blocks or releases the drain path. If that linkage develops slack, the plunger never seats fully.
In this case, the old cotter pin connection had worn down. The lever moved, but the plunger stopped short. The seal was incomplete, which allowed water to escape even though the system appeared to work.
Because the tub relies on that internal seal, even a small amount of slack translated into slow water loss.
Why Replacing the Drain Strainer Didn’t Fix It
Replacing the visible drain hardware seemed like the logical first step. The old strainer was outdated, and swapping it improved the look of the tub. But the visible drain does not control the seal in a triplever system.
The real control happens behind the overflow plate.
Until the linkage inside the wall was corrected, the tub could not hold water properly.
That is why the first repair changed nothing.
What Changed After Replacing the Triplever Assembly
I removed the old cotter pin, attached the linkage to the new faceplate, inserted the new pin, and bent it to lock it into place. Once the new assembly was connected, I threaded the plunger back into the overflow tube and secured the faceplate, tightening the screws evenly to keep the plate level.
The difference was immediate.
The lever had resistance again. The plunger seated fully. The drain closed with tension instead of slack.
I filled the tub and waited.
The water level stayed exactly where it should.
Why This Is the First Thing I’d Check Now
If a tub won’t hold water but the drain looks intact, I would remove the overflow plate before replacing visible parts. The triplever assembly hides the sealing mechanism, and it can fail without obvious signs.
In this case, the problem looked like a drain issue. It was not. It was a worn linkage and a loose cotter pin behind the faceplate.
Replacing that one internal component fixed the seal and brought the entire system back to proper function.