3 Ways To Test For Mold In Your Drinking Water

If you suspect you have mold in your drinking water, it’s normal to be worried because continuous mold exposure can cause various health issues. So how do you know for sure that your drinking water has mold and how can you test this to be absolutely certain?

The only way to test for mold in your drinking water is to use a mold detection kit or consult a specialist. You could also place some water in a sterile petri dish and check for signs of mold a few days later but this method isn’t accurate.

If your water smells earthy or musty or your faucets have mold around them, it could indicate mold and you should have your water treated or checked asap.

Using an accurate method for testing your drinking water for mold is important because it will allow you to take the appropriate action and understand the mold strain you’re dealing with.

This will then allow you to fix the source of the issue so you can have fresh drinking water again.

NOTE: If you suspect mold in your drinking water ideally you should stop drinking it. Mold in your drinking water can cause a variety of negative health symptoms and it should absolutely be avoided.

If you suspect mold in your drinking water find an alternative clean water source to get your drinking water from until you get the water tested and the issue resolved.

How To Test for Mold in Drinking Water

Below are the best ways to test for mold in your drinking water: 

Use a Mold Detection Kit

Using a mold detection kit involves ordering one from a reputable lab and following the instructions on the box. It’s a relatively quick and very reliable method of checking for mold in drinking water.

Unfortunately, there aren't really any reliable kits where you can test and get the results at home. It needs to be sent off to a lab for testing. But this can give you more accurate results as to whether or not you have mold plus what specific strain.

Your kit will probably come with a small sterile bottle you’ll need to fill with a sample of your drinking water. It will also come with a dropper lid to accurately place water drops on the included test strip. 

You’ll then need to send it to the lab for analysis (most labs include free shipping). 

Here’s what happens after you send your sample to the lab: 

  • The lab will analyze the water and email you the results within a few working days.
  • The analysis will include which mold or fungi strains are in your drinking water and the concentration
  • If you want a more in-depth analysis (including bacteria, cancer-causing agents, and more), you’ll need to pay more for a more extensive service

As long as you buy a mold detection kit from a reputable lab and follow the instructions closely, your results will be accurate as an expert analyzes them professionally using suitable equipment.  

Expect to pay a decent amount for this test ($100+), but the investment is worth it for your health.

You can purchase the ETR Laboratories Mold & Fungi Detection Kit, which is easy to use and gives clear results. You'll pay just under $100 and this included everything. 

Be careful before ordering because not all water test kits check for mold (the ones from Amazon only analyze the water quality and bacteria). 

Consult a Mold Detection Professional 

Instead of using a home test kit, you could consult a mold professional to test your drinking water. 

The mold expert will come to your home and take samples of your drinking water. This is a great option if you suspect you have mold elsewhere because they could also test your air quality and take samples from your walls and other surfaces. 

Depending on where you live, consulting a mold detection professional will cost between $250 to $600. 

Use the Petri Dish Method 

If you’re on a budget, you can test your drinking water for mold using the petri dish method. You can buy these inexpensively from Amazon in a pack of 10. 

10 Sterile Plastic Petri Dishes (70 x 15mm)
$6.89

Contains 10 sterile petri dishes with lids great for cultivation of fungi, bacteria and other microorgamisms.

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03/07/2024 05:37 pm GMT

Here’s how it works: 

1. Place a few drops of water in each petri dish. It’s a good idea to take a sample from each faucet in your home and place them in separate petri dishes so you can see if only one faucet is to blame. 

2. Have a control petri dish from a known clean water source (eg. distilled water or bottled water)

3. Cover the petri dishes with foil, secure with tape, and leave them for 5 days. 

4. If you notice dark black, green or grey spots (or a white fuzzy growth), you likely have mold in your water. 

This method is unfortunately not accurate because any mold could be due to the conditions in the petri dish – a dark and humid environment promotes mold growth. 

Still, it's a cheap way to do an initial test before consulting and paying a professional to do the tests for you. Just don't completely rely on the results this gives you.

Check for Signs of Mold

While it's not a definitive scientific test and can be inaccurate there are ways to check for mold in your drinking water. Certain signs can indicate that you have a mold problem.

When you suspect mold in your drinking water, it’s best to stop drinking it and use bottled water instead until you eradicate it. 

Depending on the strain, drinking moldy water can cause physical symptoms such as: 

  • Allergy symptoms (e.g. sneezing, coughing, runny nose, rash and wheezing)
  • Vomiting 
  • Diarrhea

Below are the most common signs of mold in drinking water: 

The Water’s Taste Has Recently Changed

If you notice a change in your drinking water’s taste, it could be due to mold. 

This is more likely if the new taste is musty, iron-like, or earthy but if you’re unsure, you should get your water tested.

Run the Faucet and Check for a Moldy Smell

Once mold starts growing and colonizing, it releases spores into the environment which can have an earthy, musty, rotten or ammonia-like smell. 

Run the faucet for a couple of minutes and place your face close by so you can smell the water. If other people also complain of a strange, moldy smell in your drinking water, there’s a good chance it has mold.

Check for Visible Mold Signs

It’s normal for mold to grow in warm, dark and moist environments, such as bathrooms. However, if you notice the mold is more severe than normal, the water itself may contain mold. 

Look for mold growth (dark spots, a white or black film or dark slime) in the following places: 

  • Around faucets
  • Inside an accessible water pipe (mold can enter water pipes if there’s a crack or break).
  • In your reusable water bottles and their lids, especially if you clean and deep clean them often. If you have an stainless steel bottle, shine a flashlight inside to check for mold. 
  • Tiny dark specs in the drinking water
  • Abnormally severe mold in the shower or bathtub.
  • Toilet bowl. Look for a black gritty substance, which can indicate mold. 
  • Water filters. Not changing filters regularly can lead to mold accumulation. This includes water bottle filters.
  • Water softener systems. If you don’t clean the tank regularly, it can cause mold in your drinking water. 

If your home has rising damp or is prone to mold growth, these are the ideal conditions for mold to enter the drinking water through a cracked pipe, water filter or water softener system. 

If you have a well and the cap is dislodged or worn out, mold could enter your drinking water in that way. 

How To Eradicate and Prevent Mold in Drinking Water

Now that you know how to test for mold in your drinking water, you’re probably keen to eradicate it and prevent it from happening again:

Have a Plumber Fix Any Cracked Water Pipes 

If you noticed mold in an accessible water pipe, you likely have a crack or break in the system but the mold issue should resolve after a plumber has repaired or replaced it. 

Replace Your Water Filter Regularly 

If you use a water filtration system for drinking water, be sure to replace the filter every 6 to 12 months to prevent mold and keep other contaminants out. 

Clean Out Your Water Softener System’s Tank 

A moldy water softener tank can be cleaned by scraping off the moldy build-up and giving it a good clean with hot water and dish soap. After that, fill it with water and soak it with half a cup of bleach to kill the mold spores. 

Deep Clean Your Reusable Water Bottles and Clean Them Daily 

You should deep clean reusable water bottles and their lids once a month. This involves dismantling the lid if it has a spout or straw, cleaning it and soaking it in white vinegar to sanitize it (my favorite method).

Cleaning your water bottle every day is also a great way to prevent mold from forming in the first place.