Does Bleach Kill Mold?
Bleach kills mold on hard, non-porous surfaces like tile, glass, and countertops. However, it is largely ineffective on porous surfaces like wood, drywall, and grout because it cannot reach mold roots. For porous materials, other products or professional remediation may be needed.
Key Takeaways
- On non-porous surfaces, bleach kills mold on contact.
- Never mix bleach with ammonia, vinegar, or other cleaners - dangerous gases can form.
- Bleach can damage or discolor some surfaces and materials; test in an inconspicuous area first.
Explanation
On non-porous surfaces, bleach kills mold on contact. The sodium hypochlorite in bleach destroys mold and its spores on surfaces like bathtub tile, glass, and sealed countertops. It also removes mold stains, making it appear completely gone.
The problem with porous materials is that mold grows roots (hyphae) beneath the surface. Bleach is mostly water, which does not penetrate well, while the chlorine stays on the surface. This kills surface mold but leaves roots alive to regrow, sometimes within days.
For porous surfaces, better options include hydrogen peroxide, vinegar, borax solutions, or commercial mold removers designed for penetration. Large mold problems (over 10 square feet) or mold in HVAC systems should be handled by professionals.
Things to Know
- Never mix bleach with ammonia, vinegar, or other cleaners - dangerous gases can form.
- Bleach can damage or discolor some surfaces and materials; test in an inconspicuous area first.
- Wear protective gear when using bleach for mold: gloves, eye protection, and ensure good ventilation.