To kill mold with bleach, use a ratio of 1 cup bleach for every gallon of water. Bleach can only effectively kill mold on nonporous surfaces as it is unable to penetrate into materials with deep pores such as cinder block, wood, carpet or ceiling tiles.
Mold growth occurs when there is water damage. It is important to eliminate the source of this damage before removing mold. Check for leaky pipes, signs of recent flooding and high humidity levels. Fully protect yourself from the mold and bleach by wearing a respirator, goggles and long rubber gloves. Before using bleach, be sure to open any windows and doors to allow for ventilation.
The active ingredient in bleach is sodium hypochlorite, the main ingredient in most mold removal products. Using bleach is not the most effective way to clean mold, because the chlorine in bleach inhibits the chemical’s ability to penetrate porous surfaces. Bleach is also corrosive and can damage the surface you are trying to clean.
A good alternative to bleach is vinegar. Spray white distilled vinegar on any moldy surface, and allow it to sit for one hour before cleaning the area with water. Other less corrosive mold removal products include Borax, hydrogen peroxide and tea tree oil.