Mildew thrives in warm, damp areas. This makes your bathroom, and any other area of the home with similar conditions, a virtual breeding ground for this hazardous growth. The best mildew stain remover will depend on the item you are cleaning, the extent of the growth, and your own personal preferences.
The first factor to consider when attacking a mildew stain is the extent of the problem. In some cases, cleaning the item in question may not be a viable solution. If the mildew has attacked a significant area of wallpaper or wood, or a mildew stain on fabric covers a large area of the piece, you may be better off discarding and replacing the item. This is especially true if the mildew growth is taking place on a difficult-to-reach place, such as the underside of peeling wallpaper.
If you decide that the stain is manageable and you want to attack it, you have two simple cleaning solutions available to you that may already be stashed away in your home. The first, and easiest, mildew stain remover is a solution of bleach diluted in water. Mix about one part bleach to three parts of water. Test this on an inconspicuous area of the item first, then scrub or soak the affected area.
A comparable alternative to bleach is to make a similar solution with rubbing alcohol. Mix one part rubbing alcohol and one part water. Test a small area of the item for colorfastness, then soak or scrub with the solution. For small, fabric items, launder the entire piece after the stain has been removed. Upholstery should be dried as quickly as possible in the sun or with a fan or hair drier.
If you have neither of these items readily available in your home, or are interested in a more environmentally friendly approach, you can use a commercial mildew stain remover. H2Orange2® has a lower toxicity than bleach and is a greener alternative. Mix with water according to the package directions before application.
The variety of mildew stain remover options should provide a satisfactory solution for nearly any treatable mildew stain. Clean the damaged items as soon as possible after discovering the mildew. After the stain has been treated, try to discern the cause of the mildew growth and the source of any excessive dampness within the house.
Once the mildew problem has been cleaned up, you should follow up by taking actions to prevent further growth in the future. Use a dehumidifier in problem areas to keep your home dry. Mildew-resistant paint can be used throughout the house, and is especially prudent in bathrooms and kitchens where mildew can thrive. Silica gel stored in closets and drawers can keep the contents dry.