Bathtubs are too small. Bathtubs are too big.
Bathtubs are too small because when we lie down in them our spine goes into flexion, or a C shape, a position we want to avoid. If bathtubs were longer we could lie flat and float which is healthy for our spine.
Bathtubs are too big because the energy used to heat up the hot water is inefficient.
How do we balance this out? I'll explore solution in my upcoming book.
The above oversized long copper bathtub is from our custom built home in Ubud, Bali.