On Saturday, March 21, 2015 at 4:23:02 AM UTC-4, wrote:
I keep seeing these walk in bathtubs advertised on tv commercials. They
have a side that opens like a door. THey are intended for the elderly.
The concept makes sense, because I am aware of how difficult it is for
elders with health issues. However, I find it hard to understand how
they can seal those "doors" on the tubs, to be water tight. And even if
they do have a good seal, how long do they last?

Like the door seal on a refrigerator, car door, etc, they all seem to
fail fairly fast. But for a bathtub, there is a lot of pressure against
that seal. I'm not sure of the water capacity, but even 25 gallons
weighs about 208 lbs (one gallon is 8.34 lbs). That's a lot of weight
against a gasket/seal. And I would think they hold more than 25
gallons.

Of course if the gasket fails, that's a lot of water to flow on the
floor and will cause a lot of damage.

IDK anything about the reliability of the door seals. But I wouldn't
worry about the pressure against the seal being some difficult design
problem. Those kinds of design typically don't rely on the seal material
to hold the pressure back. It would be logical to use the weight of the
water to your advantage by having the seal between the door and the area
of the door opening the door presses against. The more pressure, the
tighter it pushes against the seal. I haven't looked at one, but I
would think it's probably the design they would have. Over time the
seal might start to leak and need replacing, but I don't see some
difficult design issue or catastrophic problem. If it leaks, it's
going to start slowly, not a big flood.