Mold in a Sonoma County rental: what tenants and landlords should know
What the law says
According to CDPH, California's State Housing Law (Health and Safety Code section 17920.3(a)(13)) makes visible mold growth, as determined by a health or code enforcement officer, a condition that can deem a residential building substandard. Since January 1, 2016, if dampness or visible mold in a dwelling is a danger to occupants' health, the dwelling is substandard and the owner must remediate (CDPH). CDPH also notes that city and county building and health departments are responsible for enforcing the State Housing Law.
Steps for tenants
- Document it: photos with dates, notes on leaks and smells.
- Notify the landlord in writing and keep a copy.
- Reduce moisture you control: run exhaust fans, use a dehumidifier, report leaks promptly.
- If nothing happens, contact your local code enforcement agency and ask for an inspection. CDPH says finding the right agency can take some effort because responsibility varies by city and county. Inside city limits, start with your city; in unincorporated areas, the County.
- Health concerns: talk with your doctor.
CDPH's Air Quality Section doesn't do inspections or enforce housing codes, so local agencies are the place to go. This isn't legal advice; for disputes, consider a tenant rights organization or an attorney.
Steps for landlords
- Fix leaks and moisture sources quickly; the EPA says drying within 24 to 48 hours usually prevents mold (EPA).
- Have mold removed properly, not painted over.
- Keep records of repairs.
Need a provider? Request help or see mold remediation.
Want a local pro to take a look?It's free for homeowners and there's no obligation.
Sources
Sources checked October 18, 2026.