Is it Mold or Mildew?
Concerns about mold can be alarming for both tenants and landlords. And while landlords are responsible for the general habitabilty of an apartment, tenants are responsible for the regular cleaning and generally their lease states that they cannot create a dangerous situation by their inactions.
Mold vs. Mildew: Key Differences
Many people use “mold” and “mildew” interchangeably, but they’re not the same:
Mildew is a surface fungus—often gray or white—that thrives in damp, warm areas such as bathroom tile or shower grout, bathroom walls and ceilings and window sills . It’s usually powdery or fluffy, easy to wipe away, and rarely causes structural damage. While it is a type of mold, it is not the “mold” that is reference when people are talking about dangerous, health-affecting molds or “black mold” caused by ongoing water intrusion.
Mold grows deeper into materials like drywall, wood, or insulation. It can be black, green, or brown, often producing a musty odor. Certain species, particularly those linked to water damage, can harm indoor air quality and pose health risks.
Understanding this distinction matters, because mildew can typically be cleaned with regular household products, while mold may require professional remediation.
Natural Mold Is Everywhere
Mold spores are a natural part of our environment. They drift in from outdoors on breezes, through open doors and windows, and even on clothing and shoes. Because of this constant air exchange, some mold spores are always present indoors, even in well-ventilated homes with high-quality air filtration.
Professional inspectors compare indoor spore counts with the natural outdoor baseline. The goal is to identify:
Elevated Indoor Levels: Counts significantly higher than what’s naturally present outside.
Water-Damage Species: Certain molds that thrive only in damp indoor environments and are rarely found outdoors.
If neither of these conditions is present, the report will indicate that no elevated mold levels were found, even though ordinary background spores remain.
Responsibility and Costs
Under California law, landlords are responsible for remediating confirmed mold problems. However, when tests show no elevation beyond the outdoor baseline, the property is considered habitable.
Health Considerations
If anyone in the household experiences symptoms they believe are related to mold exposure, it’s worth noting that outdoor mold levels are generally higher than indoor levels. A medical evaluation can help identify the actual cause and rule out other triggers.
Prevention and Cooperation
Even with professional cleaning, mold-resistant paint, and functioning ventilation fans, ongoing maintenance is key. Weekly and monthly deep cleaning of shower walls, ceilings, and other high-moisture areas is essential. Landlords can provide ventilation upgrades, but tenant cooperation in regular cleaning remains critical to keeping bathrooms mold-free.
