Water splashing onto the basement floor poses a safety hazard. Surround the hot tub with flooring materials that prevent falls when they're wet, such as rubber mats. The water may also cause structural damage if it's allowed to sit on the floor. Lifting the tub off the floor allows for a proper drain line. Install moisture-resistant flooring materials, such as tile, around the base of the tub.
The high heat and evaporating water from the hot tub increases the basement's humidity level. When the moist air from the hot tub hits the cool air of the room, condensation forms. The condensation builds up on walls, windows, heating ducts, electrical outlets and fixtures. The damp condensation can facilitate mold growth or cause other moisture damage, including rot.
To combat the increased amount of humidity and prevent condensation, include ventilation in the room. Central air conditioning in the warmer months dehumidifies the air, while during the colder months the heat from the furnace helps dry the humid air. But this isn't enough to address all condensation concerns. Install an exhaust fan, and vent it to the outside of the house. To ensure that all condensation is removed, also install a mechanical ventilation system. It continuously vents fresh outside air into the house and exhausts the interior air.
Consult with an architect or a contractor experienced with properly installing indoor hot tubs. The individual should be able to identify the best place to install the hot tub and understand ventilation systems. The contractor may also suggest installing other appropriate materials such as moisture-resistant insulation.