Can You Use Bleach to Kill Mold?
Bleach is often thought of as the “go-to” cleaner for tough problems-but when it comes to mold, the truth is more complicated.
When Bleach Works
Bleach can kill mold on non-porous surfaces like:
- Glass
- Tile
- Stainless steel
On these materials, mold stays on the surface, so bleach can wipe it out fairly effectively.
Where Bleach Fails
On porous materials such as:
- Wood
- Drywall
- Ceilings
- Concrete
…mold doesn’t just sit on the surface-it grows roots (called hyphae) deep inside. Because bleach is water-based, it can’t penetrate far enough to kill the mold at its source.
Why Bleach Can Make Mold Worse
- Using bleach on porous surfaces may actually backfire:
- The water content in bleach can soak in, creating more moisture for mold to feed on.
- Bleach may cause mold to release spores, spreading the problem into the air.
- Mold can return quickly, making it seem like it was never cleaned.
A Common Problem in HVAC Systems
Many homeowners try bleach on A/C vents or ductwork, only to find the mold keeps coming back. That’s because bleach only cleans what’s visible-it doesn’t resolve the underlying moisture or contamination issue.
The Bottom Line
Bleach can kill mold-but only in very limited situations, and only on hard, non-porous surfaces. For porous materials or recurring mold issues, a deeper solution is needed-one that removes mold at its source rather than just hiding it temporarily.
If you’re tired of the bleach-clean-repeat cycle, check out our Handling Mold Problems page and learn how to treat mold the right way—without demolition and without toxic chemicals. Also take a look at our Blog page to see why DIY methods should be avoided.
