Home Improvement: Bleach Doesn’t Kill Mold

by Becky BlantonMay 26, 2016

Every homeowner knows “unwanted water or moisture causes water damage and mold,” but do they know why, and more importantly, do they know how to kill the mold that often results.

Image of damage caused by damp on a wall in modern house

Where does water damage start?

Most water damage in a home comes from one of three scenarios:

Leaks are the unwanted, unintended and inevitable consequence of owning a home. Leaks can occur from poor drainage outside the home, such as improper gutter placement, grading of the property, run-off from outside your property, such as construction nearby, clogged street drains, flooding, ice dams in your gutter, bad roofing, etc. In other words, something outside or inside the home that is not supposed to leak is leaking. Leaks occur with age, improper repairs, earthquakes or natural settling of a home. They happen, and at some time in the life of your home, you will have a leak. It may come from a dishwasher, washing machine, hot water heater or toilet, burst pipes, but it will happen. Learn where leaks occur, how to spot them, how to fix them and how to make sure mold doesn’t become a secondary issue.

Flooding occurs when water arrives in overwhelming and sudden amounts in your home, yard or on your property. Flooding typically comes from nature, either in a thunderstorm, tornado, hurricane, or simply hours or days of intense rain that create flooding in what experts call a “fire hose” of moisture.

New homeowners don’t often realize it, but the humidity of a home can cause water damage too.

Water Damage

Water damage can mean anything from ruined drywall, delaminated plywood or chipboard, rusting metal, rotting wood or mold growth. Of all the damage water can do, mold is what scares most homeowners.

Mold will actually start growing immediately after spores are attached to an item, usually within the same day or hour depending on how and where water hits a home. Mold can easily grow within 24 to 48 hours, and will begin to colonize in 1 to 12 days. Unless you are recovering from a flood or major water event where you know mold could be an issue, mold is usually already a problem before it is discovered.

Image of damaged moldy wall

What Can Water Damage Affect?

No part of a home is safe from water, and the hard thing for homebuyers is that unless an expert is hired to evaluate a home, including the air quality, it’s easy to miss even major areas of mold damage, including basements, walls, attics, insulation and even roofing tile!

“When someone cleans up mold using bleach, they eliminate the mold stains,” Hoffman said. “Bleach is very, very good at getting rid of stains.” By the time conditions are right for the mold to return (high humidity etc.), the new homeowners may already be in the home, and my not even realize the mold has returned. The leak may have been fixed, but the mold may not have been.

“The belief that bleach kills mold is pervasive,” Hoffman said. “People honestly believe they’ve killed the mold by bleaching it, and don’t realize they have only eliminated the stain, not the spores, and not the mold.”

Mold is the Primary Damage from Water and Moisture

Even though FEMA hands out cases of bleach after a disaster, and tells residents to use it to disinfect their homes and property, the fact is, bleach does not kill mold.

“It’s great at getting rid of stains, which makes people think they’ve killed the mold,” said mold expert, Doug Hoffman. Hoffman, who lives in Louisiana, was among the consultants on mold cleanup after Hurricane Katrina. Doug is also the Executive Director of the National Organization of Remediators and Mold Inspectors (NORMI).

Image of person cleaning fungus on the corner of the wall
“Bleach doesn’t kill mold. As strong as it is, it just can’t penetrate what I call ‘the bio slime’ of mold. You need an enzyme cleaner to do that.”

“The active ingredient in bleach is sodium hypochlorite. If you’re a label reader you’ll see that this is the active ingredient in almost every cleaner on the market. It’s very effective in removing the discoloration caused by mold, but it leaves the micro flora that will enable the mold to return in exactly the same spot when conditions, like humidity and moisture, are right,” Hoffman said.

“You can use hydrogen peroxide to kill small areas of mold, but there are better and stronger safe organic methods. We prefer green products that are non-toxic, good for the environment and safe for the homeowner, and very effective as well. When you use the right kind of anti-microbial, the mold will be destroyed and the underlying bio-slime will be annihilated. We use a product called EnyzMagic201. It’s USDA labeled GRAS (Generally Regarded as Safe), is 100 percent biodegradable and harmless to humans, animals, and marine and plant life. It’s also non-flammable and can be used safely in low ventilation areas.

Hoffman isn’t alone in his findings about bleach. The Journal of Forest Products commissioned a study by Oregon State University to study the effect of bleach on mold as well.

NORMI offers a free mold remediation guide for anyone with mold problems. The guide describes how to remove mold from a variety of surfaces, including books, clothing, drapes, walls, carpet, wood and cinderblocks.

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About The Author
Becky Blanton
Becky Blanton is a full-time ghostwriter and writing coach for Fortune 500 companies, CEOs, and business speakers. In 2009 she spoke at TED Global at Oxford University, her first ever public speaking gig. When she's not writing, she's kayaking in the Chesapeake Bay. Her dream home is to live aboard a sailing or houseboat.