Mildew that is present on walls is the result of moisture that has gone untouched in your home. One of the most common places for mildew is in a basement. A basement that has a high moisture content will be susceptible to mildew if precautions are not taken.
Reducing the amount of moisture in your basement can done by using a dehumidifier. You can attach a hose to run water from the dehumidifier into a nearby drain. If this is not an option, the reservoir needs to be emptied when it gets full.
You can tell that moisture is in the air by the smell of the room. A sour smell is a good indicator of high levels of moisture. If you have not been into the basement of an empty house, you should put on a mask before going downstairs.
Examine the walls of the basement and look for the presence of mildew. This can appear as small black dots on the wall or large splotches. Removing mold from the walls can be done with a chemical mildew and mold remover. However, you can make your own mildew remover by using chlorine bleach.
Fill a 1-gallon milk jug nearly full with water and then add one-half cup of chlorine bleach. A one-third cup of laundry powder can also be added. Insert a small funnel into a spray bottle and the fill it up with your bleach solution.
Put on a face mask before spraying your bleach solution on your walls. Go to the basement and saturate the walls that have mildew with the bleach solution. Make sure you use enough solution to make all the walls wet but not too runny. Allow the solution to sit on the walls for a few hours and check for mildew remnants. If the wall is discolored, the bleach has removed all the mildew.