Walk-in tub Draining
How long does it take to drain a walk-in tub? The same amount of time a regular tub takes to drain, except you need to wait until this happens before exiting. The standard tub drain and p trap is 1 1/2″. The p trap is plumbed into the main sewer drain. Gravity and a 1 1/2″ tub drain will only allow so much water through it regardless how many holes are drilled in the bottom of a tub. You could increase the diameter of the p trap and drain going to the larger grey water line, but unless the work is easily accessible, plumbing costs and repair likely wouldn’t make it practical.
Optional Quick Drain technology offered by some distributors will come with a disclaimer because they have the potential to cause damage to drains and p-traps. Drainage is made up of series of pipes, glue joints, and rubber couplings, all well suited for naturally
vented drainage. An electric pump forcing more water through drains than they were designed for can stress connections and push water out of p-traps allowing waste gases to enter into a home.
Here is one such disclaimer:
Although American Standard® has taken reasonable precautions to ensure that the Quick Drain TM is suitable for residential plumbing; it is the responsibility of the installer to insure that the plumbing is acceptable for use of the Quick Drain TM. American Standard® does not accept responsibility for damage arising from use of the Quick Drain TM
It should only take about 2 1/2 minutes for a walk-in tub with a single drain and natural drainage to completely empty. Bathers usually will use the shower wand to rinse soap off themselves and the tub during this short time. You’ll have to decide if the slight improvement you may or may not gain by adding a second drain or another electric pump is worth the extra expense. Having experienced both types, our installers have not seen any difference between them.