What is TDS Controller/MTDS and Mineralizer? Which One to Choose?
If you are planning to buy a new RO water purifier and have done some research online or offline then you must have come across some RO purifiers that come with an extra feature called ‘TDS Controller’ or MTDS.
It is also interesting to note that this same feature is sometimes marketed as a ‘TDS Modulator’ by some water purifier brands.
However, the TDS Controller, MTDS, and TDS Modulator are the same thing and there is no functional difference between each of them.
Different manufacturers use different terms for the same feature or functionality.
While Kent uses the term ‘TDS Controller”, Aquaguard or Eureka Forbes uses the term MTDS (Manual Total Dissolved Solids Controller).
But they all perform the same function.
What the heck is this TDS Controller/MTDS?
The following text will answer all your questions about the TDS controller in an easy and user-friendly manner.
Let’s begin then.
What is a TDS Controller or MTDS in a Water Purifier?
In simple terms, a TDS Controller or MTDS is a device that controls the TDS (Total Dissolved Solids) of water. Unlike the filters, cartridges, and membrane(s), the TDS Controller does not filter or purify the water in any way.
The image above shows a typical TDS controller, as you can see this is a small device. This is quite inexpensive and costs roughly around Rs. 50 only.
How Does TDS Controller Work?
TDS Controller or MTDS is a manual device that consists of two water inputs, one water output, and a TDS Control screw.
Water Input 1: Purified water output from the RO membrane
Water Input 2:
a) Purified Water from Activated Carbon Filter in case of RO+UV+TDS Controller Water Purifiers
OR
b) Purified Water from UF Membrane in case of RO+UF+UV+TDS Controller or RO+UF+TDS Controller Water Purifiers
Water Output: Mix of two water inputs in the required ratio.
TDS Control Screw: TDS Control screw controls the TDS value in output water by manually adjusting the flow of water from the two water inputs.
I) If TDS needs to be reduced then the flow of input water from the RO membrane is increased and the flow of input water from the Activated Carbon Filter or UF membrane is reduced.
II) If TDS needs to be increased then the flow of input water from the RO membrane is reduced and the flow of input water from the Activated Carbon Filter or UF membrane is increased.
Simply, Turn the screw clockwise to reduce the TDS level or anti-clockwise to increase the TDS level.
However, if you are not comfortable doing this, we recommend getting this done by a trained professional.
Recommended TDS Level in Drinking Water?
You should adjust the TDS controller such that the TDS level of purified water is between 80 to 150 ppm.
Need and Benefits of TDS Controller?
Natural water contains several essential minerals like Calcium, and Magnesium and may also contain harmful impurities like heavy metals, fluorides, and arsenic.
These minerals and heavy metals constitute ‘Dissolved Solids’ in water. The level or the presence of these Dissolved Solids in water is commonly referred to as the TDS (Total Dissolved Solids) level of water.
The presence of minerals like calcium and magnesium in small quantities is what makes the drinking water healthy and the drinking water must contain these minerals.
RO Membranes usually remove around 90% of dissolved solids from the input water, and that includes essential minerals.
What this essentially means is, if the input water does not have high TDS then chances are the RO Membranes will reduce the level of essential minerals to a significantly low level making the water unhealthy and not fit for drinking.
This is where the role of the TDS Controller comes into effect. As detailed above, in such a scenario when the TDS level of the input water is not so high, a TDS Controller can be used to increase the TDS of purified water to a healthy level.
The TDS Controller is used to increase the level of essential minerals in the purified water.
TDS Controller: Can it be Harmful?
In our opinion, the TDS Controller or MTDS is not an ideal way to add essential minerals to purified water. In RO purifiers with a TDS controller, 100% of the input water does not pass through the RO membrane.
Mixing RO-purified water with non-RO-purified water may result in the presence of several harmful heavy metals like lead and arsenic in the purified water, as these impurities can only be removed by an RO membrane.
Should you Buy an RO with a TDS Controller or MTDS?
Keeping all the above discussion in mind, you should only consider buying an RO purifier with a TDS Controller or MTDS if:
• The TDS Level of input/raw water is low (lower than 900 ppm).
• Water does not contain heavy metals like lead and arsenic.
If the TDS level of the raw/input water is high (higher than 900 ppm) or if the water contains harmful heavy metals then you should not choose an RO purifier with a TDS Controller.
Be sure to check the specifications of the RO membrane before deciding to buy an RO purifier with a TDS Controller or without a TDS Controller.
Which Water Purifier with TDS Controller to Choose?
Now, if you have zeroed in on buying an RO purifier with a TDS Controller then the following table will help you in finding the perfect match for your home.
| TDS LEVEL | IS WATER MUDDY? | PRESENCE OF BIOLOGICAL IMPURITIES? | IDEAL CHOICE |
|---|---|---|---|
| 500 – 900 ppm | No | No | RO+TDS Controller/Mineralizer |
| 500 – 900 ppm | No | Yes | RO+UV+TDS Controller/Mineralizer |
| 500 – 900 ppm | Yes | No | RO+UF+TDS Controller/Mineralizer or RO+UV+UF+TDS Controller/Mineralizer |
| 500 – 900 ppm | Yes | Yes | RO+UV+UF+TDS Controller/Mineralizer |
| Over 900 ppm | No | No | RO |
| Over 900 ppm | No | Yes | RO+UV |
| Over 900 ppm | Yes | No | RO+UF or RO+UV+UF |
| Over 900 ppm | Yes | Yes | RO+UV+UF |
Is there any Better Alternative to the TDS Controller?
There are now better technologies available to add back the essential minerals removed by RO purification.
RO purifiers with Mineralizer cartridges are a much better option as compared to RO purifiers with TDS Controllers. Because in RO purifiers with a Mineralizer feature, 100% of the water passes through the RO membrane. This removes any possible chances of harmful dissolved solids and heavy metals accidentally entering your drinking water.
The next section talks about Mineralizer, the difference between TDS Controller and Mineralizer, and which one is better.
What is a Mineralizer or Mineral Cartridge?
RO Membrane does not differentiate between the good particles and the bad particles/impurities. This is one of the disadvantages of using an RO purifier.
RO also removes essential minerals like calcium and magnesium from the water, so we need some way to add back the minerals removed during RO purification.
One way of doing that is by using a TDS Controller/Modulator, we have already discussed this in detail above.
Another, slightly more effective, way to add essential minerals is a ‘Mineralizer or Mineral Cartridge’.
A mineralizer or Mineral Cartridge adds back essential minerals like Magnesium and Calcium in the proper concentration and helps in maintaining proper PH and Acid-alkaline balance in the water.
Below is an image of a typical mineral cartridge:
As you can see in the image above, the mineralizer (AKA Mineral Cartridge) consists of several types of particles. Water passes from one end to the other and several essential minerals are added, and the acidic nature of water is reduced by balancing the PH value.
Difference Between a TDS Controller and a Mineralizer?
| TDS CONTROLLER/MTDS | MINERALIZER/MINERAL CARTRIDGE |
|---|---|
| 100% of the input water is not passed through RO Membrane. | 100% of the input water is purified by RO Membrane. |
| Not ideal for water containing harmful heavy metals like lead and arsenic. | Since 100% water passes through RO purification, heavy metals like lead and arsenic are removed. |
| TDS Levels of purified water can be increased or decreased. | No option to control the TDS level of purified water. |
| Small and costs very little. | The size is the same as regular filters and cartridges used in RO purifiers, costing over Rs. 500. |
Mineralizer or TDS Controller, Which One is Better?
Both Mineralizer and TDS Controller features are quite useful and provide excellent benefits if used appropriately.
If the water supply contains industrial impurities like lead and arsenic then you should avoid buying an RO purifier with a TDS Controller. Apart from that, RO purifiers with TDS Controllers work well in most scenarios.
RO purifiers with the Mineralizer feature can be used for water infected with lead and arsenic but these purifiers have no option to adjust the TDS level as per your requirement.
So, the answer to the question ‘Whether to choose an RO purifier with TDS Controller or Mineralizer’ would depend on factors like the presence of industrial impurities and your choice.
However, we feel RO purifiers with the mineralizer feature have a little upper hand as compared to the RO purifiers with the TDS Controller feature.
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Very clear information. Thank you
Recently, I have purchased a new Mineral RO+UV+MF+MP water purifier(from Pureit). It’s giving 20 TDS after purification. I know, its low TDS level.
But, Installation Engineer from Pureit said its mineral Water after purification and good for drinking. Can you suggest on his comment?
Please answer I’m from a rural area and the water TDS is more than 700 then which ro is good ro+uv+tds Or ro+uv+mineraliser.
We recommend going for a RO+UV+Mineralizer water purifier because of the obvious reasons stated in this post.
Can we use municipal water for R0+UV+TDS water purifiers?
We have tds water 380 , which purifier to be used? It’s water from well
Any RO+UV water purifier should be fine.
That depends on the TDS value of the municipal water coming to your home. Generally, municipal water does not have a very high TDS. If the TDS level is below 500 mg/L then you can also consider any good UV+UF water purifier. But make sure the water purifies has an Activated Carbon Filter for removing impurities like Chlorine, as the municipal water generally contains Chlorine.
Can we use ro +uv +mineraliser for mixed water. Tds varies from 100 to 400 .what are your reviews about havells max sea green
Hi
I get the water which is a mix of both ground and muncipal water. TDS ranges from 370-450. Should I prefer RO water purifier? If yes which is good? If not, which water purifier can I go for?
Thanks
You should go for RO+UV or RO+UV+Mineralizer water purifier.
Hi, How to find if the water has arsenic and lead?
You can get the water tested in a water testing lab or you can use a lead and arsenic water test kit. You may also test the drinking water yourself with the help of a home water test kit.
Thanks for the helpful article
I would like to buy a purifier without the TDS, which one would you recommend?
Very informative article, many thanks for publishing this on daily essential intake of every being.
May I seek a few clarifications –
1. For less ppm, i believe a normal Water purifier is good enough and RO is an overkill . Is that true ?
2. Where can I get the TDS controller ? havent seen any available yet.
3. Our community has a centralised RO Unit and provides < 100 TDS for drinking and washing purposes. Is it good idea to use RO water for washing purposes ? One advantage I see is that less corrosion in plumbing lines.
Many thanks in advance for answering !
Please find point-wise replies to your queries.
1. If the input water has low TDS and if it doesn’t contain any harmful heavy metals like lead & arsenic then there is no need to use RO purifiers.
2. TDS Controller should only be used with RO purifiers with the provision for the same. If you have a water purifier with TDS controller, then like all parts, TDS controller can also be bought separately. You can view this TDS controller available on Amazon.in.
3. It is a well-known fact that RO purification results in a lot of wastewater. Looking at the shortage of drinking water in India and across the globe, we believe RO purified water should ideally be used for drinking purposes only and not for washing. If your community has a problem of hard water then the best solution would be to use a water softener.
Is Alkaline water RO like Bluebird using Mineralizer technology?
We have not yet reviewed any water purifiers from this brand so we can’t really comment on it.
How does TDS depend on rate of flow of water ? If we increase the rate of flow of water will TDS increase ?
Who said that?