I have an older bathtub that uses a trip-lever drain and I have noticed that it does not retain all of the water when the drain-stop is engaged. By this I mean if you had filled a bathtub and came back in ten minutes, you would notice the water had decreased by an inch or so. When I think of how much effort is usually required to be 100% water-tight (crush washers, sweating pipes, series of o-rings and washers), this makes sense - a simple metal bobber settling via gravity in the drain pipe is nowhere near what anyone would consider "sealed".

In a ballpark measurement, how water-tight should trip lever drains be?

  • 1
    Imagine a new one would be more water tight than yours. Depends if you are okay with it or want go to trouble of finding a replacement and repairing/modifying , or wait till you get a new bathtub. Do you need the bathtub to hold water for emergencies?
    – crip659
    Commented Jul 26, 2021 at 22:00

1 Answer 1


On the contrary, they should be fairly watertight. Loosing an inch in ten minutes is quite a bit of water. The metal bopper has more than gravity working for it, it has the weight of the water in the tub too. If the bopper is smooth and clean and the receiver is also smooth and clean, it should be pretty close to water tight. I have them in my tubs that I fill up before hurricanes in case we lose water and the tubs stay filled for days.

  • I explored this issue more and discovered that there is a leak in the drain pipe itself, before the trip lever plunger blocks the flow of water. I imagine this is the source of the water leakage. Commented Jul 28, 2021 at 2:27
  • Is the water leaking inside the house or into the ground? What foundation is this - slab on grade, pier and beam, basement, . . . ? Commented Jul 30, 2021 at 9:25

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