How to Reduce TDS of Water Coming Out of Your RO System
Written by: Gene Fitzgerald // Last Updated: Jul 28, 2023
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If you’ve recently measured the TDS level of your reverse osmosis water and have noticed an unusually high reading, you might have to take some steps to remedy the situation.
While it’s possible that this is only a temporary issue that won’t develop into anything more serious, the opposite could also be true…
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Key Takeaways
You can further reduce RO water TDS by:
- Removing the remineralization filter (if there is one)
- Replacing an old RO membrane
- Using 2 membranes in sequence
- Increasing feed water pressure
- Lowering feed water temperature
- Adding deionization and/or nanofiltration to your setup
How to Reduce TDS of Water Coming Out of Your RO System
So, how can you reduce the TDS of water coming out of your reverse osmosis system?
Reducing the TDS level of your reverse osmosis water starts with identifying the root cause for the problem. There are several common reasons for a reverse osmosis system to produce water with a high TDS level, and most of those are easy to address without any professional assistance.
Remove Remineralization Filter
If you have a remineralization filter, you should keep in mind that it contributes a lot to the overall TDS level of your output water. You should remove the filter and see if the situation improves. If it doesn’t, then the problem likely lies elsewhere.
By the way, this is the most common reason for having high TDS levels in RO water.
Replace Old Reverse Osmosis Membrane
Perhaps it’s been a while since you last replaced your reverse osmosis membrane? The membrane needs to be swapped out regularly in order to maintain the optimal performance of the system. Usually, once every two to five years is enough, but in some cases you might have to do it more often than that. This depends mostly on how contaminated your water is in the first place, and how much you consume on a daily basis.
Use 2 RO Membranes in Sequence
It’s possible that a single reverse osmosis membrane is simply not enough for your situation. This is often the case when your input water has a very high TDS level. In this case, a second membrane can help remove additional contaminants from the water.
The great thing about this setup is that it scales very well.
Increase Feed Water Pressure
You may have insufficient pressure in your feed water for the reverse osmosis membrane to function correctly. If possible, try increasing the pressure gradually and run some tests in between.
Be careful not to bring up the pressure too much, as this could have negative consequences of its own.
Reduce Feed Water Temperature
High water temperature is another factor that negatively affects the operation of reverse osmosis membranes. Hot water causes the membrane to expand, which results in more contaminants being able to make their way through. Make sure to only feed cold water into your reverse osmosis system, whenever you have a choice.
Add Deionization/Nanofiltration
If nothing else helps, you might have to go a different route. A deionization or nanofiltration stage could effectively reduce the TDS levels of your water, but it’s usually a more expensive option, which is why most people tend to keep it as a last resort.
Further Reading:
How Can I Reduce RO Water TDS Naturally?
If you don’t want to use any advanced setups and want to lower the TDS level of your reverse osmosis through natural means, here are the options you should consider:
- Stop remineralizing your water
- Increase the pressure of your feed water
- Decrease the temperature of your feed water
What Is TDS in Water and How to Measure It?
TDS simply refers to “Total Dissolved Solids”. In other words, this is a measure of all solid materials dissolved in your water. Keep in mind that not all of these are necessarily harmful. Minerals also fall in this category, but they are beneficial in certain amounts. In general though, high TDS levels are indicative of poor water quality – at least when it comes to reverse osmosis.
Reverse osmosis aside, anything above 1,200 ppm is not acceptable for drinking.
Measuring the TDS level of water is simple and straightforward with the help of a digital TDS meter. You simply insert it into a sample of your water and wait for the readings to appear. Keeping a TDS meter around can be handy if you want to stay on top of the performance of your reverse osmosis system.
What’s the Ideal TDS Level in Drinking Water?
Drinking water should be below 300 ppm to be considered excellent in quality. Going above that is still acceptable – up to 600, actually – but the quality of water does begin to noticeably decline around that point. Reverse osmosis can bring your water TDS down to as little as 10 – 50 ppm, which is a huge improvement even over baseline “excellent” water.
If you have any questions about how to decrease the TDS of RO water systems please don’t hesitate to leave a comment below!
About the Author Gene Fitzgerald
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