As mentioned, wooden tubs hold more water than spas because of their depth – one of their biggest advantages in terms of the bathing experience. This obviously means they are somewhat heavier and that a good solid base is required. Whether free-standing or partially sunk, they need to stand on a level, re-inforced concrete pad – 4” thick on top of 4” hardcore.
Both a water supply (garden hose) for filling, and a land drain for emptying, needs to be close to hand.
Finally, an electrical source is needed for the heater/control unit and pumps:
Low Force – 16A
White Force – 25A
High Force – 32A