How to Improve Water TDS in an RO System
Written by: Gene Fitzgerald // Last Updated: Jul 28, 2023
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When you’re using a reverse osmosis system, the TDS level of your water should be pretty good already. That’s part of the point of using a reverse osmosis system in the first place.
However, sometimes you might notice readings that are simply too high. Alternatively, you may want to push things upwards yourself and raise the TDS level of your reverse osmosis water – in order to improve taste or prevent corrosion.
Either way, find out how to improve the TDS levels of your RO system below!
Contents
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Key Takeaways
Here is how to improve water TDS in an RO system:
- Remineralization, TDS controllers, and pressure/temperature adjustments are some of the options available for increasing the TDS of RO water.
- Replacing the RO membrane or adding an extra one, increasing feed water pressure, reducing feed water temperature, or adding deionization/nanofiltration are possible solutions for high TDS levels.
How to Improve Water TDS in an RO System
So, how to improve water TDS in an RO system?
Let’s take a look at some options available for improving the water TDS in a reverse osmosis system. Note that not all of those will be valid for your situation, so make sure to understand your reverse osmosis setup well enough in the first place.
How to Increase TDS in an RO System
If you’re specifically looking to increase the TDS of your reverse osmosis water, here are some methods to consider. You can
- remineralize your water,
- increase the TDS or temperature of the feed water,
- or even reduce the pressure of the input line.
- Using a TDS controller is also an option.
However, most of these approaches come with some potential downsides that you need to keep in mind.
Remineralization
Remineralization is easy and not expensive to implement. The most straightforward option is to install a remineralization filter. It will add minerals to your water as it passes through. Obviously, this should always be done as a post-filtration stage. Alternatively, you can use mineral drops in your filtered water, or even pour it out of an alkaline pitcher.
Remineralization will increase RO water TDS considerably.
Further Reading:
Increasing Feed Water TDS/Temperature
Increasing the TDS of your feed water will increase the TDS of the filtered water as well – and the increase will be proportional. However, this is not an optimal approach, because it will increase the strain on your reverse osmosis system, and it’s more wasteful compared to increasing the TDS of your filtered water instead.
Increasing the temperature of your feed water is also an option, but once again, not a very optimal one. This will cause your reverse osmosis membrane to expand and allow some contaminants through, which can have various negative effects in the long run.
Reducing Feed Water Pressure
You could also decrease the pressure on the feed water side. This comes with some negative repercussions of its own, most notably the fact that it lowers the performance of your reverse osmosis system and produces more wastewater.
TDS Controller
A TDS controller works by mixing your filtered reverse osmosis water with the original input water. It aims to maintain a certain proportion between the two, which can give you more control over TDS levels.
Unfortunately, the process also reintroduces some contaminants into your water, so you have to be careful about the contents of the input water.
How to Reduce TDS in an RO System
More commonly, you’d be looking to reduce the TDS of your reverse osmosis system. This is usually done when you notice that the TDS levels of your filtered water are abnormally high, which could indicate problems with the performance of your system. Reducing the TDS of your filtered water is a bit trickier, but it’s certainly possible if you know what you’re doing.
Replace an Old RO Membrane
Perhaps it’s simply time to replace your reverse osmosis membrane?
You need to remember to replace it every couple of years – sometimes more often, depending on the kinds of contaminants you’re dealing with.
If it’s been a while since you last replaced your reverse osmosis membrane, this is the most likely culprit.
Using 2 or More RO Membranes in a Row
You can also consider installing an additional reverse osmosis stage to your filtration setup. This may be necessary if the TDS level of your input water is too high for your reverse osmosis system to effectively reduce it to reasonable levels.
A second membrane is more than enough in pretty much all of those cases, due to the way its performance scales in a chain.
Increasing Feed Water Pressure
If possible, try increasing the pressure in your feed water line. This isn’t always an option, and even when it is, it could have some unintended consequences that you should be prepared for. Be ready to bring the pressure back down if you start noticing certain side effects in the operation of your plumbing.
Reducing Feed Water Temperature
The same goes for the temperature of your feed water. If the water is too warm, it could negatively affect the operation of your reverse osmosis system by causing the membrane to expand.
Even worse, consistently high temperatures could cause long-term problems with your reverse osmosis system, requiring you to replace the membrane more often.
Deionization and Nanofiltration
Deionization and nanofiltration are also possible solutions when none of the above work. Keep in mind that those might cost a bit more than the average modification to your reverse osmosis system, so you should exhaust all your other options before reaching for this one.
What TDS Level in Drinking Water is Right?
You should ideally try to maintain your drinking water at a TDS level below 300. Going above that can still be acceptable, but it’s the point where water quality starts to noticeably decline.
If you’re using a reverse osmosis system, the bar is even lower than that. You should never see your water TDS exceeding 50 in that case. If it does, this likely indicates a problem with the reverse osmosis system itself.
If you have any questions about how to improve TDS in an RO system please don’t hesitate to leave a comment below!
About the Author Gene Fitzgerald
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