Merced County, CA Swimming Pools & Spas: Hot Tub Rules (2026)

The definitions reproduced in the Merced County Building Permit Guide, drawn from the California Pool Safety Act, state that a swimming pool includes any structure intended for swimming or recreational bathing that contains water over 18 inches deep, and expressly includes hot tubs, spas, portable spas, and nonportable wading pools. As a result, a permanent in-ground spa is treated like a pool: it requires a building permit, a site plan, engineered plans, and the State-mandated safety features. The County's permit exemption for prefabricated pools and spas applies to spas too, so a prefabricated spa accessory to a single-family residence, duplex, or lodging house is exempt from the building permit when entirely above grade and not exceeding 5,000 gallons, although plumbing and electrical permits may be required and the State barrier requirements still apply. When a building permit is issued for a new or remodeled spa at a private single-family home, the Pool Safety Act's requirement for at least two of seven drowning-prevention safety features applies, and where an enclosure is used it must meet the 60-inch enclosure and self-latching gate standards of HSC 115923. Commercial and public spas (for example at apartments or HOAs) follow the County Environmental Health spa requirements under California Building Code Chapter 31B.