California mold laws: what the Health and Safety Code says

• Section 26147's landlord mold-disclosure duty covers mold that exceeds the permissible exposure limits set under Section 26103 or poses a health threat under the department's guidelines. “residential landlords shall provide written disclosure to prospective and current tenants of the affected units as specified in subdivision (b) when the residential landlord knows, or has reasonable cause to believe, that mold, both visible and invisible or hidden, is present that affects the unit or the building and the mold either exceeds the permissible exposure limits to molds established by subdivisions (a), (b), and (c) of Section 26103 or poses a health threat according to the department’s guidelines” (Cal. Health & Safety Code §26147(a), checked 2026-09-23)
• Section 26147 does not apply until six months after the department adopts standards under Sections 26103 and 26105 and develops guidelines under Section 26130. “The requirements of this section shall not apply until the first January 1 or July 1 that occurs at least six months after the department adopts standards pursuant to Sections 26103 and 26105 and develops guidelines pursuant to Section 26130.” (Cal. Health & Safety Code §26147(e), checked 2026-09-23)

• As of January 1, 2016, mold is a condition that makes a home substandard in California. “As of January 1, 2016, mold is also a condition that makes a home substandard in California.” (CDPH Indoor Air Quality, Mold, checked 2026-09-23)
• The substandard-building list includes visible mold growth as determined by a health officer or code enforcement officer, excluding minor mold on surfaces that collect moisture as part of their normal use. “(13) Visible mold growth, as determined by a health officer or a code enforcement officer, as defined in Section 829.5 of the Penal Code, excluding the presence of mold that is minor and found on surfaces that can accumulate moisture as part of their properly functioning and intended use.” (Cal. Health & Safety Code §17920.3(a)(13), checked 2026-09-23)
• Dampness in living spaces has long been listed as a condition that makes a home substandard. “Dampness in your home living spaces has long been listed as a condition making a home substandard to a code inspector.” (CDPH Indoor Air Quality, Mold, checked 2026-09-23)
• The owner of a rental property cited as substandard by a local code inspector is required to repair the condition. “The owner of a rental property cited as substandard by a local (city or county) code inspector is required to repair the substandard condition.” (CDPH Indoor Air Quality, Mold, checked 2026-09-23)
• Visible mold can be cited by local code enforcement so that the owner is required to remediate it. “The visible mold can be cited by local code enforcement so that the owner is required to remediate the problem.” (CDPH Indoor Air Quality, Mold, checked 2026-09-23)
• The CDPH indoor air quality group does not do enforcement or inspections. “Note that our small group at CDPH does not do enforcement or inspections, but provides information to the public and does research to assist protection of the public.” (CDPH Indoor Air Quality, Mold, checked 2026-09-23)
• As of January 1, 2022, California rental housing providers must give prospective tenants the state's mold booklet. “As of Jan. 1, 2022, California rental housing providers are required to provide this mold booklet to prospective tenants.” (CDPH Indoor Air Quality, Mold, checked 2026-09-23)
• Section 26148 requires its disclosure to be provided to prospective residential tenants before they enter the rental or lease agreement. “The requirements of this section shall be provided to prospective residential tenants prior to entering the rental or lease agreement.” (Cal. Health & Safety Code §26148(b), checked 2026-09-23)

• A residential landlord is not required to run air or surface tests to find out whether mold exceeds the permissible exposure limits. “a residential landlord shall not be required to conduct air or surface tests of units or buildings to determine whether the presence of molds exceeds the permissible exposure limits to molds” (Cal. Health & Safety Code §26147(b), checked 2026-09-23)
• CDPH's position remains that available evidence does not support science-based permissible exposure limits for indoor mold. “available evidence did not support the establishment of science-based PELs for indoor molds at that time. This view remains the CDPH position to date.” (CDPH Indoor Air Quality, Mold, checked 2026-09-23)

Visible mold growth, as determined by a health officer or code enforcement officer, is a substandard-building condition under Health and Safety Code §17920.3, excluding minor mold on surfaces that accumulate moisture as part of their normal use. An owner cited by a local code inspector must repair it.

Section 26147 of the Toxic Mold Protection Act covers mold above permissible exposure limits or posing a health threat under the department's guidelines, but it does not apply until the department adopts those standards, and CDPH has not set them. Landlords must, since January 1, 2022, give prospective tenants the state's mold booklet.

Section 26147(b) says a residential landlord is not required to run air or surface tests to determine whether mold exceeds the permissible exposure limits.

Local code enforcement. The CDPH indoor air quality group does not do enforcement or inspections.