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

Antioch Municipal Code Title 9, Article 20 is captioned 'Swimming Pools and Hot Tubs' and groups both uses under a single set of accessory-structure standards (sections 9-5.2001 et seq.). California Health and Safety Code section 115921 reinforces this by defining 'swimming pool' to include 'hot tubs, spas, portable spas, and nonportable wading pools.' That means any spa or hot tub holding water over 18 inches deep is subject to the drowning-prevention requirements of HSC section 115922 when a building permit is issued, including either an isolation enclosure meeting section 115923 or a safety pool cover meeting ASTM F1346-23. A locking, ASTM-compliant safety cover is the most common compliance path for residential hot tubs because the cover itself counts as one of the two required drowning-prevention features and substitutes for a separate fence enclosure. Hot tubs and spas also trigger a city building permit for the structure, gas line, and electrical hookup; electrical bonding follows the 2025 California Electrical Code, and water heaters require a seismic gas shutoff and a 110-percent-of-capacity drain pan or proper drain line under California Plumbing Code section 504. Acoustic equipment (pump/heater) for residential spas must not violate the city's general noise standards.