Can Reverse Osmosis Water Cause Diarrhea?

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While reverse osmosis is frequently praised for its water purification capabilities, you might occasionally see people reporting unusual side effects from drinking RO water – like diarrhea.

As with anything similar, you should take these claims with a grain of salt because you never know the full context.

Still, could there be anything to worry about in the first place? Can reverse osmosis water really cause diarrhea or other digestive problems? Let’s find out!

Key Takeaways

  • Under normal circumstances, reverse osmosis water does not cause diarrhea.
  • The only scenario when RO water might cause diarrhea is if it’s been contaminated with pathogens or other contaminants due to filtration or storage being faulty.

Can Reverse Osmosis Water Cause Diarrhea?

So, can reverse osmosis water cause diarrhea?

No, reverse osmosis water by itself cannot cause diarrhea. It’s just pure water with close to all impurities removed – in that context, it would actually make more sense to expect the opposite. After all, diarrhea resulting from drinking water is generally caused by the presence of certain contaminants, so reverse osmosis technically reduces the likelihood of anything bad happening.

At least one study has shown that drinking alkaline-reduced water can have a positive impact on people suffering from chronic digestive problems, particularly those with diarrhea issues.

woman with stomach problems feeling unwell

How Could Reverse Osmosis Water Cause Diarrhea?

The only way you could get diarrhea from reverse osmosis water is if there are any contaminants present in it. That should generally not be the case when it comes to reverse osmosis water, as the main point of the RO process is to purify water as thoroughly as possible.

However, in some cases you might still end up with contaminated water without even realizing it. For example, you might have bacteria growing in your RO storage tank. Since water has already passed through the reverse osmosis membrane at that point and doesn’t get filtered again, there’s nothing stopping those bacteria from ending up in your drinking water.

How to Prevent RO Water from Causing Diarrhea

Preventing diarrhea from drinking reverse osmosis water is all about ensuring that you keep your RO system in check. Make sure to regularly replace all filters according to the manufacturer’s instructions, and keep the system sanitized. You should perform a deeper sanitization every 1-2 years to stay on the safe side, especially if you live in an area with more serious contamination problems. Some other things you can do:

  • Avoid storing filtered water for too long
  • Install a point-of-use system if possible – that way you’ll dispense water directly from the RO system without having it pass through your home’s plumbing
  • Check the condition of your pipes if your building is very old and hasn’t been renovated in a while

Can RO Water Cause Other Stomach Problems?

By itself, no. Reverse osmosis water should cause no problems in an otherwise healthy person, stomach-related or otherwise. As long as you ensure that you maintain a healthy diet and don’t suffer from any deficiencies – particularly in minerals – there should be no health risks associated with drinking reverse osmosis water on a regular basis.

What Pathogens Can Reverse Osmosis Remove from Water?

Reverse osmosis removes pretty much all microorganisms from water very effectively, leaving nothing but pure water in the end. This includes:

  • Protozoa
  • Algae
  • Fungi
  • Viruses
  • Parasites

Keep in mind that some of those might start growing directly in your reverse osmosis system. However, as long as that happens before the point of filtration, it shouldn’t be a problem – those pathogens will get filtered out in the process anyway. What’s more problematic is when pathogens develop at some point after the reverse osmosis system, for example in the storage tank. In that case, they could realistically make it into your drinking water.

bacteria in water

Does Reverse Osmosis Have Any Side Effects?

The reverse osmosis process itself does have a few minor side effects which should not be ignored. For most people, those factors will make no difference at all – but it’s still important to remember that they are present.

Loss of Essential Minerals

Reverse osmosis removes pretty much all impurities from water. This includes various dangerous elements, but also a few normally healthy ones. Most notably, minerals like calcium, magnesium, and potassium. Those are normally present in water in various amounts and having them in your diet is good to some extent. Reverse osmosis strips them away completely – so if you’re concerned about the mineral balance of your diet, you will need to take specific steps to remedy that. You have lots of options available – mineral drops, remineralization filters, or supplements.

Lower Water pH

The water produced by reverse osmosis is slightly acidic by default – it has a lower pH level than normal water. This is generally not a problem as the level is not low enough to cause health problems, but it does mean you should be careful about points like where you’re storing your water and what materials it passes through on its way to your drinking glass. Due to its acidity, reverse osmosis water can occasionally leach materials from storage containers and pipes.

If you have any thoughts about the question, can RO water cause diarrhea, please don’t hesitate to leave a comment below!

About the Author Alexandra Uta

Alex is a content writer with an affinity for research and a methodical attention to detail. Since 2020, she has fully immersed herself into the home water treatment industry only to become an expert herself. Alex has been using water filters and similar products for years which has gained her lots of hands-on experience.
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