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TDS Explained – Drinking Water TDS Level Chart

Drinking Water TDS Level Chart

What is the primary source of water for this planet? Yes, you have guessed it right. It is rainfall and the rivers that flow down the mountain slopes into the sea. As the water flows through the rocks and the soil, it picks up the minerals and salts from the ground.

Usually, these minerals comprise sodium, calcium, magnesium, etc. This natural process improves the taste of the water by raising its pH level.

TDS is Totally Dissolved Solids.

pH scale of water

Low pH levels increase the acidity content of the water and make it unfit for drinking.

In addition to the natural minerals, this river water has to contend with other impurities like human and animal waste, industrial pollutants, etc. Industrial waste released into the rivers constitutes heavy metals like lead, arsenic, and even mercury.

These minerals and salts are present in the water in varying degrees of concentration. This makes the water dangerous for drinking in its present form.

Hence, you need best water purifiers to purify this water and eliminate the harmful chemicals. We shall talk about the various TDS levels later on in this article.

How to Measure TDS Level of Water?

But, for the moment we shall concentrate on measuring the TDS level in the water. How do you do that?

You must have noticed that the water purifier technician uses a small hand-held device similar to a thermometer to check out whether the water you get is pure or not. This hand-held device indicates the level of TDS in any solution like water.

These dissolved ionized solids increase the conductivity of the water. This TDS meter measures this conductivity and estimates the quantity of TDS present in the solution.

Using a TDS meter is very easy. We explain the procedure involved in brief.

  • Collect the sample water in a clean cup
  • Switch on your TDS meter and remove the cap.
  • You have two electrodes at the end of the meter. Insert the electrodes into the water. Never submerge the entire meter as you can risk damaging it.
  • Ensure that there are no bubbles attached to the ends of the electrodes. You can shake it off by stirring the water lightly with the meter.
  • Wait for about 5 seconds so that the reading stabilises. This is your TDS reading
  • Remove the meter from the water and shake off the excess liquid from the ends of the electrode. Place the cap over the meter and store it safely.

The result is just a number that flashes on the screen as soon as you place the instrument in contact with the water. This number indicates the quantity of dissolved solids in the water.Any value in the range of 300 mg/litre (ppm) to 500 mg/litre is good. TDS levels above 500 mg/litre indicate that the water is hard and hence requires purifying.

Any value below 70 mg/litre increases the acidity content in the water thereby making it unfit for consumption. Levels over 2000 mg/litre are not at all potable.

It is very important to note that the TDS meter indicates the amount of TDS in water. It does not give any indication of the nature of contaminants present in it. It can happen that the TDS levels of water could be 300 ppm.

What is TDS Controller/Modulator?

Normally, the RO process ensures the removal of 90% of TDS. Hence, if the TDS levels of input source water are around 1500 ppm, the TDS levels of pure water after RO purification comes to around 150 ppm.

Water with TDS levels of 150 ppm does not have a good taste because of the elimination of essential minerals like sodium, magnesium, and calcium. Therefore, the water has a lower pH level and hence tastes bitter.

You require a special mechanism known as the TDS controller/modulator to rectify this anomaly. There is a need to bring the TDS levels of water in the range of 300 ppm to 500 ppm. Let us see how the TDS controller works.

Kent RO Purification Stages
Kent RO Purification Stages

The basic system is such that the water that goes into the RO process is split into two parts. One part goes through the RO membrane and the output you have is pure RO water.

As discussed earlier, this water has a lower level of TDS. The other part of the water does not go through the RO membrane.

Instead, it passes through the UF membrane or a UV chamber depending on the configuration of the water purifier. This output will also be pure water but with the same levels of TDS as input source water.

Now, comes the interesting part. The system ensures the mixing of both these water outputs. There is a valve that controls the flow of water from the Part 2 assembly.

This effectively controls the TDS. If you notice the configuration of the water purifiers you will find that the TDS controller is always paired along with the UV chamber or the UF membrane.The resultant water contains optimum levels of TDS. This is very useful in case the source water has low levels of TDS.

Understand that water with low levels of TDS does not constitute that the water is pure. This is why you need to purify water with low TDS levels by passing it through the UF membrane or the UV chamber.

You can also refer to the TDS controller as a TDS modulator because it controls as well as modulates the amount of TDS in the water.

TDS Controller vs Mineralizer

You have seen what is the function of TDS Controller. Let us see how mineralizers differ in functionality.

The mineralizer works on the principles of ionization and electrolysis. This process involves the passing of variable low voltage Direct Current into the ionization chamber to enable the process of electrolysis.

There is a release of positively charged ions of copper and silver. Copper and silver ions have anti-toxic properties. Silver is a natural toxin for bacteria and copper to algae.

The release of these positively charged ions purifies the water completely without causing any side effects that you would usually observe when you use chlorine for purification. The resultant water has a refreshing smell and taste.

In addition to removing the toxicity, the mineralizer ensures the release of essential minerals lost during the RO purification process. This enables selective infusion of minerals.

This is not possible in the case of TDS controllers. When you use TDS controllers, you mix purified source water with normal TDS along with RO purified water with a minimum concentration of TDS.

The Mineralizer differs in the sense that it infuses the lost minerals alone and this certainly does not include the heavy metal impurities like arsenic, lead, or mercury.

This is not to say that the TDS controller is ineffective or anything of that sort. Both TDS controller and the Mineralizer have their importance in the water purification process.

Drinking Water TDS Level Chart

Ideally speaking extremely pure water has a pH level of 7. Anything below 7 and the water becomes acidic. A figure over 7 makes the water alkaline.

The ideal pH value for drinking water should be in the range of 7 to 8.5.

Drinking Water TDS Level Chart

Water with a pH level of 7 is pure but does not have a good taste. It is in fact, tasteless, colourless, and odourless. You need some amount of TDS and minerals in the water for the taste to improve.

Hence, the TDS Controllers and mineralizers have their importance.

Depending on the TDS levels of water, we can now state the following.

  • TDS levels below 300 – Excellent
  • TDS levels between 300 to 600 – Good
  • TDS levels in the range 600 to 900 – Fair
  • TDS between 900 and 1200 – Poor
  • TDS levels above 1200 – Unacceptable

Thus, we infer that drinking water is considered acceptable if it has TDS levels up to 600. Patients with kidney problems should go for water that has TDS levels in the range of 100 ppm.

Understand that water with a low concentration of TDS is also not acceptable for human consumption. This is because the water does not have the valuable minerals essential for the proper growth of our body.

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