"Spa" means a basin of water designed for recreational or therapeutic use that is not drained, cleaned, or refilled for each user. It may include hydrojet circulation, hot water, cold water mineral bath, air induction bubbles, or some combination thereof. It includes "therapeutic pools", "hydrotherapy pools", "whirlpools", "cold spas", "hot spas", and "hot tubs". It does not include these facilities at individual single-family residences intended for use by the occupant and his or her guests.
210 ILCS 125/3.10