What is a TDS Controller in a Water Purifier? How does it work, its benefits, and More!

While searching for a water purifier for your home, you will have come across the term TDS controller, and after hearing it if you have been confused about what it means, what it does? Or have asked yourself the question – do I need a TDS controller? then worry not; we’ve got you covered!

With the article, you can understand what a TDS controller is, how it works and its benefits based on which you will be able to make an informed decision whether you need one or not!


What is TDS?

To understand what a TDS controller is, let’s first look at what exactly is TDS?

TDS or total dissolved solids is the term used to represent the organic and inorganic matter that can be found dissolved in water. TDS will constitute of calcium, sodium, magnesium, and potassium cations and carbonate, hydrogen carbonate, chloride, sulfate, and nitrate anions.

For your body to function, you require an optimum amount of TDS, but when the TDS is in high amounts or consists of harmful constituents, it might harm your health; hence before consuming any water, you need to check the TDS. We have described the optimum levels of TDS in the section below.


What is a TDS Controller?

What is TDS controller

As is suggested by its name, a TDS controller is a device that helps control the TDS level in the water. A TDS controller is fitted into your RO water purifiers and will help maintain the TDS of water. 

Though it does not require any manual intervention, you can set a desired level of TDS to maintain the optimum level. It is advised that the TDS of drinking water should be between 50-150 ppm to ensure that there is no harm to your health.


How does a TDS Controller work?

How Does a TDS Controller Work

A TDS controller is a valve-like device that maintains the TDS of water at the desired level by using salts from the source water. When the water flows down from the RO filter after checking the level of TDS –

1. If it is lower than the desired amount-

The flow of input water from the RO membrane is reduced, and the flow from the UF membrane or activated charcoal filter is increased. 


2. If it is higher than the desired amount-

Then the flow of water from the RO membrane is increased and the flow of water from the UF membrane and activated charcoal filter is decreased.

In this way, the TDS controller maintains the optimum level of TDS in your water.


What are the Benefits of a TDS controller? 

Now that we know what a TDS controller is, let’s look at its advantages-

  • As you must have noticed by how it works, a TDS controller will help you control the level of TDS in water and maintain it at safe levels to ensure the good health of you and your family.
  • The TDS controller is easy to operate and will let you control and set the desired amount of TDS, But before doing that, you are advised to look at the optimum levels as mentioned in the following section.
  • TDS controller will help add minerals to your water, making it taste more natural, and for some people, it may seem tastier.
  • TDS water uses the source water to make adjustments; hence it reduces water wastage making it eco-friendly.


What is the acceptable value of TDS?

Now that you know what a TDS controller is and its benefits, you should look into the optimum levels of TDS.

According to the Bureau of Indian Standards, the optimum TDS level for drinking water should be less than 500mg/litre above which the drinking water is not safe and can prove harmful to your health. 

Before drinking water, you can conduct a small test to gauge the levels of TDS and compare it with the table given below –

Level Of TDS (mg/litre) Comments 
<50 Very less amount of minerals 
50-300 Excellent 
300- 500 Good
500-900 Fair, Can be drunk after treatments
900-1200 Poor, Unfit for consumption
>1200 dangerous

You can use a TDS meter to measure the amount of TDS in your water and compare it with the table above. For levels above 300, it is advisable to use an RO water purifier with a TDS controller to maintain the optimum level of TDS. 

When deciding what  TDS level you should set your TDS controller on, it will be best to set it at the average amount, which is 150.


Should I buy a Water Purifier with a TDS controller?

Should I buy a Water purifier with a TDS controller

So you have checked the levels of TDS in your water, and after reading the above sections, know the workings and benefits of a TDS controller, But is it really required for your home? To decide upon this, answer the following two questions-

1. Is the level of TDS in your water lower than 900 ppm?

If your answer is Yes-

You should buy a RO water purifier with a TDS controller as the RO membrane will reduce the value of TDS by 90%, and you will require a TDS controller to bring it back to the optimum level.

If your answer is No-

You do not need a water purifier with a TDS controller.


2. Does the water that comes to your home contain heavy metals like Lead and Arsenic?

If your answer is Yes-

You should not buy a TDS controller and invest in a RO water purifier with a mineralizer cartridge.

If your answer is No-

You can buy a TDS controller, considering the TDS of water is below 900 PPM; otherwise, you don’t require it. 


Which Water purifier should I buy According to the level of TDS?

You can check the table below to understand what will best suit your needs-

What is the TDS level? (ppm) Is the water muddy? Are there biological impurities? Best Water Purifier 
500-900 No No RO+TDS Controller
500-900 No Yes RO+UV+TDS Controller
500-900 Yes No RO+UF+TDS Controller or RO+UV+UF+TDS Controller
500-900 Yes Yes RO+UV+UF+TDS Controller
>900 NO No RO
>900 No Yes RO+UV
>900 Yes No RO+UF or RO+UV+UF
>900 Yes Yes RO+UV+UF

In the table RO- Reverse osmosis water purifier, UV- Ultraviolet Water Purifier, UF- ultrafiltration water purifier.



1. Are there alternatives to the TDS controller?

Yes, TDS Controllers in recent times are being replaced by newer technology known as Mineralizer cartridges. A TDS controller, while trying to achieve the set level of TDS, will use the source water to increase the mineral content, But while doing this, sometimes it may end up adding harmful minerals from the source water; the Mineralizer cartridges eliminate this problem.

Mineralizer cartridges come equipped with essential minerals like calcium and magnesium, which are added according to the requirement without any involvement of the source water.


2. What methods can I use to check the TDS of water?

You can check the TDS of water by using a TDS meter, using a filter paper and scale, or by using an electrical conductivity meter.


Also Read:

Best Non-Electric Water Purifier in India

Best Gravity Based Water Purifier in India

Best Water Purifier under 15000 in India



What is a TDS Controller? How does it work? And what are its advantages? You can now answer all these questions having read about them in this article. Moreover, you also know the optimum level of TDS required in your water so as to maintain your health.

 Armed with this information you can now make an informed decision on which type of water purifier will best suit your requirements!

Tell us in the comments which point you found to be most useful!

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