Bleach

• Best known for working to remove laundry stains and for disinfecting germ-infested areas, bleach contains compounds called surfactants. These compounds allow bleach to easily slip inside the cells of organic material like germs, mold and mildew, Because bleach can get inside them, it kills them efficiently by doing damage inside and out.
  
  

Plumbing Issues

• If you bathroom sink or shower drain smells musty, you could have mildew growing inside the pipe. Bleach kills mildew and deodorizes the pipe. Pour a cup of bleach into the drain and let it sit for a half-hour. Douse a cleaning brush with bleach and scrub the interior of the drainpipe. Run water into the drain for about 30 seconds to remove the bleach and any lingering bits of mildew.
  
  

Alternatives

• Household bleach isn't strong enough to eat through the hair and other detritus that usually clogs pipes. If a stopped up pipe is the plumbing problem you're looking to clear, leave the bleach in the laundry room. Instead, fill the sink or shower just enough to cover the bottom of the plunger. Plunge the drain until the clog moves down the pipe and the water slides into the drain. If you smell a lingering sour odor from the clog, pour ½ cup bleach into the drain to deodorize it.
  
  

Considerations

• When working with bleach, wear gloves and keep the area well-ventilated. If you are pouring bleach into a drain or doing something else that could cause it to splash, consider using eye protection as well. If the smell of mildew in a drain is a recurring problem, install an exhaust fan in the problem room to reduce humidity levels. Use bleach to control fungus and its smell by pouring ½ cup bleach into the problem drain once a month.