What is a TDS Meter? – How do you check TDS level in water?



Before we go into the details about the instrument known as the TDS meter, it is important to know what TDS is.

The expanded form of TDS is Totally Dissolved Solids. 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.

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.

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.

Is it safe?

Logically speaking, it should be but do you know what the 300 ppm comprises of? It could be arsenic and mercury alone. Now, is the water safe?

This brings the importance of the water purifier into the equation. We shall look at the various aspects of water filtration and purification later on in this article.


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