How to remove toxic mold and smell in drain pipes

by | Apr 2, 2017 | Mold Removal Tips

Anywhere there is moisture that sits for a prolonged time period and a food source, you are most likely going to find mold. That is why a favorite hiding and breeding place for molds (fungi) is in and on the drains (pipe sweating) of your property.

Your drains serve as the delivery mechanism of all the dirty water and food wastes that your property produces and delivers it to the city sewer pipes. Over time, these wastes such as human hair, dead skin, and old food deposits start to build up.

This build up is the perfect food for various molds and bacteria that will start to grow on the inside of the pipes if you do not clean and maintain them properly.

As these microorganisms start to thrive, they reproduce more offspring as millions die to then become food for the new generation of microbes. Before you know it, your drains will be covered in a thick pathogenic and toxic bio slime that will create a foul smell. Worse yet, this thick mold sludge may also lead to clogged pipes and extensive water damage. That is the last thing you want to happen!

Is there an odd or foul smell coming from your drains?

Think of the odor as a warning sign that something in wrong with your drains.

If so, you most likely have a mold problem or the sewer gasses are leaking into your home from the drains. This may also be a sign that your drain is not properly installed and or the lead seal around the drain has failed or become rotten. Sometimes when the lead seal fails, people will attempt a cheap fix by trying to caulk it with silicone which rarely lasts.

In order to locate the problem, you will need to do is take off the drain cover and perform a visual inspection of the drain pipe and seal. What you are looking for is mold growth and any gaps around the drain pipe and shower pan.

If there is a gap around the pipe, then you most likely have a serious water damage and mold issue hiding within your floors where the pipe is located. If it located on an upper story of a multi-story property, you most likely now have water damage and mold running down to the bottom floors.

For example, here is an image with a shower drain pipe that is not only installed incorrectly, it also has black mold in and around the pipe.

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If you find mold in your drain pipes, and or a defective seal or a gap around the pipe allowing water to leak, your safest bet to get immediate relief is to place a temporary vapor seal over the infected drains because you and your family could be breathing in the toxic off-gasses and mycotoxins from molds (fungi) and bacteria.

Next, you need to determine if it can be cleaned and or fixed properly. If it is just mold, you are in luck and can most likely clean it pretty easily. If you have a defective seal and or gap around the pipe, you may now have extensive water damage and mold hiding in your floors and within your walls.

To handle this type of problem properly, you would need to have your property professionally remediated and the plumbing repaired. This can get expensive and there is no quick or cheap fix. The good news is that your homeowner’s insurance may take care of the problem if it is an active water leak.

If you need help with a referral to professional mold inspection and mold remediator or need assistance dealing with your insurance or you would like a professional consultation, please call us at 760-818-6830.

How do you clean the drain pipes?

I recommend that you inspect your drains often for any signs of leaks, microbial growth, and foul smells. If any leaks and or smells are found, fix or clean them immediately.

Contrary to popular belief, you do not want to pour bleach down your drains. Bleach is made with highly toxic chlorine that can produce gasses that you are your family breathe in and it also contaminates our environment and our oceans. People who use bleach in their homes and poisoning themselves, their families and the world so don’t let that be you!

A quick, safe and easy fungicide you can make that will kill the mold and get rid of the smell is a combination of baking soda, white vinegar or hydrogen peroxide, and hot water.

Here are 3 quick steps to cleaning your drains:

Step 1: Get a half a cup some baking soda and slowly pour down the offending drain and let it sit overnight. This will start to kill the mold and dry up the slime.

Step 2: The next day, get 2 cups of white cleaning vinegar or hydrogen peroxide and pour it down the same drain. It should start to foam. This will also kill the mold and start to loosen the mold colony’s hold on the inside of the pipes.

Step 3: Next, get about 5-6 cups of very hot water (not boiling) and then pour it down the drain to wash away the dead mold, baking soda, and vinegar or hydrogen peroxide. You do not want to use boiling water because it can damage your pipes and connections. Especially if they are made of PVC.

Rinse and repeat the above steps as necessary. You can also do this once a week or month to stop mold from growing and to maintain clean pipes.

If you need a mold inspection, mold remediation, or would like a professional consultation, please or text call us at 760-818-6830.


  1. John Jenkins

    Hi Moe,
    Thanks for the article on moldy drains. We are currently having a terrible problem with smells coming from our drains, especially the 2 bowl sink garbage disposal side. We were bad and have used bleach and other methods including baking soda and vinegar all to no avail. At this time, we are trying your overnight method listed above. It has really been bad and our local desert plumbers never seem to figure it out. Oh, all drains appear to work properly and maintain water in the trap which are topped off if not one the drains that is used regularly.
    Any other advice is always appreciated!
    Thanks again,
    John J.
    Ft. Mohave, AZ

    • Angela Stevenson

      Get another plumber. We were told we had no leaks by the plumber that our housing association sent over. After hiring a professional. The toilet was bubbling up water through the laminate. The back of the shower was leaking and also the bath trap. My floors under the laminate are made of hdf so it was easy to see where the water had spread. The bathroom. ,2 hall cupboards and a bedroom floor were flooded. A TV blew up.



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