Tap Water and Gut Health

Have you been hearing about possible connections between tap water and gut health but aren’t sure if you should be worried? Here Hannah, one of our resident nutrition experts, breaks down everything you need to know about how to keep your drinking water safe for your gut!

It seems nowadays that every new house build or kitchen remodel needs to include a water filter.  Whether installed at the sink or plumbed through the fridge, they are becoming a must-have on every kitchen wish list.

One of the reasons people are avoiding unfiltered tap water is the addition of chlorine.  In this article, I am going to take a look at what chlorine is and the effect it has on drinking water.

Do you really need to filter the chlorine out of your water?  Or is this just a marketing ploy by filter companies to have you splashing out on unnecessary kitchen accessories?  As I look towards building our family home in the new year, what I really want to know is: can I get my matt black sink or do I need to forgo it for a plumbed-in water filter fridge?

What is Chlorine?

Most people will have heard of chlorine as the chemical used in swimming pools.  But what is it really?

Chlorine is a naturally occurring element that is an essential nutrient for plants and animals.  It is made from the breakdown of sodium chloride, commonly known as salt. 

Chlorine is available as compressed elemental gas, sodium hypochlorite solution (NaOCl), solid calcium hypochlorite (Ca(OCl)2) solution, or in tablet form as sodium dichloroisocyanurate (NaDCC). 

It is used in a myriad of products such as paper, textiles, medicines, paints, and plastics, as well as being added to your drinking water.

Why is Chlorine Added to the Water Supply?

Why is chlorine added to water?

According to the Center for Disease Control (CDC): “Chlorination is the process of adding chlorine to drinking water to disinfect it and kill germs.  Different processes can be used to achieve safe levels of chlorine in drinking water.”

When you add chlorine to drinking water you get hypochlorous acid (HOCl).  This acidifies the water which has lots of benefits for making tap water safer to drink. 

Hypochlorous acid helps to:

  • control biological growth 
  • remove compounds that change the color, taste, and odor of water
  • remove  iron, manganese, and other dissolved inorganic contaminants such as arsenic 
  • disinfect water distribution systems, preventing outbreaks of waterborne diseases such as cholera, typhoid fever, dysentery, and hepatitis A 
  • inhibit biofilm growth on filters which could otherwise lead to pressure build-up in the water system

In fact, because of all of these benefits for tap water safety, researchers believe that chlorination is responsible for a 40% increase in life expectancy in the first half of the 20th century.

And not only is effective, it is also low cost, and easy to use, as well.  You only need a small amount of chlorine to treat large volumes of water. Chlorine will continue to work in the water until all its molecules are used up.  So, if contaminants get in further down the waterway, chlorine will still be hard at work getting rid of them.

Tap Water and Gut Health: Why is Chlorine a Concern for Your Gut Health?

Over the past decade, there has been an explosion in research looking at the human gut microbiome and its effect on health and wellbeing.

These research papers are teaching us some important things.  For example, we now know that the gut microbiome starts in infancy and closely resembles the adult microbiome by the 3rd year of life.  We also have learned that some bacteria are helpful, some are harmful, but, more than anything, it is the interaction of these bacteria and their diversity which impacts health. 

And we know that the microbiome helps regulate many aspects of your health, including:

  • immune function
  • cardiovascular function
  • brain health (including the development of depression, anxiety, and age-related memory loss)
  • cancer development
  • gene expression
  • hormone regulation
  • gut function (including the development of IBS, IBD, and Crohn’s)

Related Reading: Top 5 Best Digestive Enzyme Supplements to Fix Leaky Gut

Is There Any Evidence that Chlorinated Tap Water Kills Gut Flora?

Glasses of chlorinated water on a wooden table

Well, yes there is.  

At least, there is a theoretical risk to your gut flora from drinking chlorinated water and a small body of evidence suggesting that risk may, ultimately, prove to be significant.

See, when water is chlorinated, byproducts are produced.  These byproducts are called trihalomethanes (THMs) and include:

  • chloroform
  • bromodichloromethane
  • dibromochloromethane
  • bromoform

Evidence clearly shows is that THMs are easily absorbed through the skin, lungs, and gut.  And, in animal studies, absorbed THM levels have been associated with changes in stool microbial diversity.  (Though, it is important to know that these studies often used extremely high doses of chlorine and THMs — two or more times greater than recommended for drinking water by WHO.) 

Okay, but are there any studies showing effects of chlorination on human gut microbiome diversity?

Not many.  But one recent study does suggest there may be links.  Using metagenomic analysis, researchers examined fecal samples from 60 healthy twins between 0–8 months of life and they found that the types of bacteria in the children’s guts depended on the type of water they drank at home (filtered or unfiltered tap water). 

Importantly, the researchers found that children who drank unfiltered, unboiled tap water had unhealthier gut bacteria than those who drank water, suggesting chlorine or its byproducts may harm gut health.

All that being said, filtering your water will only protect your gut bacterial health if you are extremely careful about changing your filters. This is because home water filters are easily contaminated with infectious and sometimes downright dangerous bacteria leading to filtered water actually having more harmful bacteria in it than straight tap water.  

And these bacteria can be way worse for your gut health, at least in the short-term, than the small effects from THMs in your tap water.

How Can You Minimize the Risk to Your Gut Bacteria from Tap Water?

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There are two main ways you can minimize the risk of THMs harming your gut bacteria:

  • buy a home water filter
  • get plenty of probiotics

Let’s check each of these out in more detail.

Buy a Home Water Filter

There are three types of home water filters you can consider using to get rid of the chlorine in your tap water.

1. A Water Filter Pitcher

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This is the cheapest and most straightforward option.  

Water filter pitchers are simple, refillable containers that filter your water as you add it.  They are extremely easy to use and portable. You could even take them with you to work if you want to guarantee the content of your water anywhere!

If you think you’d like to buy a water filter pitcher, ZeroWater ZP-010 is a great choice.  It is certified to remove all lead, chromium, and chlorine.  And it also removes over 99% of mercury, copper, and arsenic. 

2. Reverse Osmosis Filter

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Reverse osmosis filters are the most effective filtering systems on the market at the moment.  They remove nearly all of the chlorine plus many other pollutants. Most systems are installed under the kitchen sink, so you won’t even know it is there.

Some of the best reverse osmosis filters available are the iSpring RCC7  and APEC Top-Tier 5-stage Water Filter System

3. Whole House Filter System

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Remember how I mentioned you can absorb chlorine byproducts through your skin?  That means it’s not a bad idea to make sure all the water in your home — including the water in your bathroom sink and shower — is chlorine-free. 

Two front runners among whole-house filter systems are the Aquasana Chloramines (which filters 400,000 gallons of water and lasts for around 4 years) and the highly-acclaimed  WGB32B 3-Stage Whole House Water Filtration System.

While these types of systems are more expensive than pitcher or under-sink option, they guarantee a nearly chlorine-free home.

Just remember, whatever filter system you might choose, you keep up with the maintenance it needs!  Change your filters or have your system inspected regularly and according to the manufacturer’s instructions to keep bad bacteria from setting up shop!

Get Plenty of Probiotics Daily

Another way to make sure your gut is staying healthy — chlorine-free tap water in your home or not — is to consume the helpful bacteria which should live in your gut. 

You can do that in one of two ways: 

  • eating probiotic-rich food
  •  taking probiotic supplements

Probiotic Foods

Probiotic foods are fermented foods which contain live healthy gut bacteria.  Some common probiotic foods you could add to your daily diet include:

  • cultured, plain yogurt
  • kefir
  • sauerkraut
  • tempeh
  • kimchi
  • miso
  • kombucha
  • pickles (fermented in salt, not vinegar)
  • natto

Probiotic Supplements

Another easy way to increase the amount of probiotics you’re getting in your day is to take a probiotic supplement.  Here are three of my absolute top probiotic supplement picks for keeping a healthy gut.

3. BioCodex Florastor Maximum Strength Daily Probiotic

BioCodex Florastor Maximum Strength Daily Probiotic
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Florastor by BioCodex is a great probiotic supplement option because it contains a probiotic fungal strain — a type of probiotic microorganism that is often overlooked when people try to take care of their gut health.  (While most people pay attention to the bacteria in your gut, your microbiome also contains archaea, viruses, phages, yeast, and fungi!)

In scientific tests, Florastor helped combat changes in gut microbiota from taking antibiotics. Since chlorine kills bacteria much like antibiotics do, Florastor may be really helpful in preventing damage to your gut from chlorine. 

2. Culturelle Daily Probiotic Formula

Culturelle Daily Probiotic Formula
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Culturelle is a highly popular probiotic with high doses of probiotic bacteria and a potent dose of inulin, a well-researched prebiotic that provides food for your healthy gut bacteria. 

In essence,  Culturelle does everything to get live bacteria into your system and help them flourish once they get there.

1. TruNature Digestive Probiotic

TrueNature Digestive Probiotic
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A true “heavy hitter” on the probiotic market, TruNature claims to be able to survive the acidic environment of your gut to help repair damage caused by antibiotics and illness.  It has a remarkably high live bacteria count, three different strains of probiotics, and excellent customer reviews

Read Probiotics for Leaky Gut for a deeper dive into these probiotics and more.

Take Home Message

The jury is still out on whether chlorine significantly damages your gut microbiome.  Animal models typically use doses much higher than what you find in tap water and human studies are full of confounding variables.

However, since, as long as you take good care of it there is no harm in getting a water purifying system (other than to your bank balance) you may as well make the investment.  There are crazier things you can be spending money on, that is for sure! 

I’m thinking perhaps my black sink can wait, and a whole house purifying system should be installed instead.  At the very least I’ll have nice tasting and smelling water which doesn’t dry my skin out. And there is a good chance I’ll be protecting my family’s gut bacteria to boot!

Supplementing with butyrate may help your gut wall get stronger, healthier, and more able to do its job. Read Next: Top 5 Best Butyrate Supplements for Leaky Gut Cure


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