[Bob Ireland]

***Get a used tub and put it in your basement***

She says that she lives in a condo; who knows what the situation is - she needs to ask if there is any doubt.

For my part, I don't have a basement, but my floor is on the ground. While I have a 100 gal bladder for the bathtub, it is just one of a number of water sources I have provided for us. {😎 I'm a prepper!}

[Cletus.D.Yokel]

Standard distance for floor joists is 19-inches, on-center.
Plan your tub placement accordingly.

I would think that builders would be aware of the weight conditions of each tub they install.
Likely that they install on the joists or “sister” up some wood to carry the load.
Any tub that can hold a 100-gallon bladder can hold 100 gallons of water, too.