How to Lower the pH of RO Water
Written by: Gene Fitzgerald // Last Updated: Jul 24, 2023
This page may contain affiliate links. If you buy a product or service through such a link we earn a commission at no extra cost to you. Learn more.
Even though reverse osmosis water is slightly acidic by default, you might occasionally want to lower its pH level even more, bringing the acidity further up.
If you’ve come to the conclusion that you need your reverse osmosis water to be more acidic than it already is, we’ve prepared this short guide with some ideas on how you can accomplish that.
Contents
show
Key Takeaways
Here is how to lower the pH of RO water:
- Remove the remineralization filter from your reverse osmosis system if you’re using one.
- Add lemon juice or other food-grade acid to the water.
- Treat the water with anion exchange resin (this might not have a noticeable effect).
- Use an acid injection system.
How to Lower the pH of RO Water? There Are Several Methods!
So, how to lower the pH of RO water?
You can use any of the below methods to lower the pH level of your reverse osmosis water. Those will technically work on any kind of water, and none of those processes require reverse osmosis water specifically.
Remove Remineralization Filter
The simplest thing you can do to lower the pH of reverse osmosis water is to remove the mineralization filter of your RO system, if you’re using one. Many reverse osmosis systems feature a remineralization stage which adds minerals to the water to compensate for the ones that get removed during the filtering process. Removing this filter should bring down the pH level of your reverse osmosis water by a good deal.
Lemon Juice
You can also add some lemon juice to your water. It’s as simple as adding it to the water directly. You need very little lemon juice for a noticeable effect. For example, as little as two drops of pure lemon juice can lower the pH level of a gallon of regular water by 0.5. This effect will be much stronger with RO water.
You should add roughly 1-2 ml of lemon juice per gallon of water if you want a more noticeable reduction.
Other Food-Grade Acids
In fact, any food-grade acid will work for lowering the pH level of your RO water, generally. It doesn’t have to be lemon juice specifically. As long as it’s safe for human consumption, and you can measure the quantities reliably, you can use any other kind of acid instead of lemon juice – think citric acid.
Anion Exchange Water Treatment
You might be able to use anion exchange water treatment to make your RO water more acidic. As the name implies, anion exchange removes anions from water which act as a buffer to neutralize acids.
That said, the effect may not be very noticeable when used with reverse osmosis water since most anions have already been removed from it.
Acid Injection System
An acid injection system, while technically a valid solution, is not really an option for most households. Since these systems usually work at the point of entry, water will run through the acid injection point before reaching your reverse osmosis system at your kitchen sink.
It is different if you’re using whole house reverse osmosis which you could install before the acid injection system. However, most RO water is slightly acidic already and has a high affinity to corrode plumbing systems. Lowering the pH level of that water even further and then sending it through your pipes and appliances of your home is a really bad idea.
What Is the pH of RO Water?
The pH of reverse osmosis water is almost always between 6 and 6.5. The process is pretty reliable and consistent, and as long as the reverse osmosis filtration system itself operates properly, the final result will not deviate much from those values.
Further Reading:
Why Most Reverse Osmosis Water Is Acidic
Pure water is slightly acidic by default. And that’s pretty much all reverse osmosis water is – water that’s been stripped of all impurities it naturally holds. Some of the main contributors to the normally higher pH level of water include various minerals like calcium and magnesium.
Once these have been removed, the pH of water is pretty much neutral. But, because RO water wants to dissolve impurities so badly, it reacts with CO2 in the air forming carbonic acid. And because RO water lacks minerals like those mentioned above it cannot neutralize any acids so the water becomes acidic.
How to Test RO Water pH
If you’re not sure about the pH level of your reverse osmosis water, don’t worry – there are various tools available on the market that can help you make sense of your situation. Here are some of the most commonly used ones.
pH Strips
A pH strip is very simple to use, and provides you with an almost immediate overview of your situation. You simply dip it in water, or add a few drops of water to the strip, and you’ll soon see the water’s pH range.
pH Meter
A pH meter is a more advanced version of the above, allowing you to re-check your water’s acidity level as much as you want. The main benefit of a pH meter is that it’s reusable, so investing in one only makes sense if you can anticipate having to test your RO water often.
Litmus Paper
Using litmus paper is a very simple way to check the acidity of water. However, it’s also a bit limited in terms of the information it provides you with – you basically only see if the water is acidic or basic, based on the paper’s color, but nothing else.
Red Cabbage
Have you heard of using red cabbage for testing water for acidity? Surprisingly, it works! All you need to do is take some water (not the water you’re planning to test), blend some red cabbage into it and mix it well, then strain the mixture until you only have the liquid part left. After that, add some of your testing water to that liquid and stir well. If it turns more red, this means that the water you’re testing is acidic.
If you have any questions about how to lower the pH in RO water please don’t hesitate to leave a comment below!
About the Author Gene Fitzgerald
Information provided on BOS is for educational purposes only. The products and services we review may not be right for your individual circumstances.
We adhere to strict editorial guidelines. Rest assured, the opinions expressed have not been provided, reviewed, or otherwise endorsed by our partners – they are unbiased, independent, and the author’s alone. Our licensed experts fact-check all content for accuracy. It is accurate as of the date posted and to the best of our knowledge.