A 1:10 (1 part bleach in 10 parts water, or about 1/2 cups of bleach in 1 gallon of water) dilution (=5,000 ppm available chlorine) is appropriate for porous surfaces (wood, cloth, concrete, etc.) that cannot effectively be pre-cleaned of organic matter. Thoroughly wet surfaces with the solution and allow it to remain in contact with the surface for 10 minutes. Rinse with clean water and dry.%u201D The 1:10 dilution is typically considered too corrosive for many surfaces. One could expect to experience metal corrosion with the use of 5,000 ppm available chorine.
A 1:100 (1 part bleach to 100 parts water, or approximately 1/4 cup of bleach in 1 gallon of water) dilution supplies 500 ppm available chlorine and can be used on smooth pre-cleaned surfaces (glass, plastic, metal, etc.) The object to be disinfected should be thoroughly moistened with the solution (spray or sponged) and left to air dry.
When bleach is used as a sanitizer, it must have at least 200 ppm of available chorine, this equates to a bleach and water mixture of 1 tablespoon of bleach to 1 gallon of water.
Shelf-life: Hypochlorite solutions in tapwater at a pH>8 stored at room temperature (23C) in closed, opaque plastic containers may lose up to 40-50% of their free available chlorine level over a period of one month. There is no decomposition of undiluted sodium hypochlorite solution after 30 days when stored in a closed brown bottle.
Reference: Rutala WA, Cole EC, Thomann CA, Weber DJ. Stability and bactericidalactivity of chlorine solutions. Infect. Control Hosp. Epidemiol. 1998;19:323-7. 57.