California Implied Warranty of Habitability (Civ. Code §§ 1941–1942)

Civil Code § 1941 requires a landlord to "put it into a condition fit for such occupation, and repair all subsequent dilapidations... which render it untenantable." Section 1941.1 lists required features: effective waterproofing, working plumbing, hot and cold running water, heating, electrical lighting, sanitary premises free of vermin, and floors, stairways, and railings in good repair. In Green v. Superior Court (1974), the California Supreme Court held this warranty is implied in every residential lease and is a defense to nonpayment. Under § 1942, if the landlord fails to repair within a reasonable time (30 days presumed) after notice, the tenant may repair and deduct the cost, not exceeding "one month's rent," "not... more than twice in any 12-month period."

Breach lets a tenant repair-and-deduct, withhold rent, sue for damages and rent abatement, or raise habitability as a defense in an unlawful detainer. Substandard conditions can also trigger code-enforcement penalties and, in serious cases, civil penalties under tenant-protection statutes.