Bleach kills mildew, but some surfaces can't be bleached and many people prefer not to use caustic chemicals, but fortunately there are other options that will kill and clean mildew without bleach.
Remove Mildew From Fabric
To remove mildew from clothing mix two quarts of water with two cups of borax. Soak in the solution for one hour or until mildew stains are gone. Wash as usual.
For upholstery and other fabrics, mix 1/2 cup of borax with two cups of water. Use a sponge to scrub the mildewed area with the solution. Allow it to saturate the fabric for several hours or until the stain is gone, then rinse.
Remove Mildew From Hard Surfaces
Scrub the mildewed area with hot soapy water and an abrasive sponge and rinse well. Apply a solution of half water and half rubbing alcohol to the area and let it air dry.
For tough stains, saturate the mildew with undiluted white vinegar and let it sit for five minutes. Apply a generous amount of baking soda to an abrasive sponge and scrub until stains disappear.
You can kill and clean mildew without bleach by using these non-caustic substitutes.