If you have researched about water purifiers, one term that you would have heard for sure is TDS. All water purifier companies keep talking about it, but what exactly is it and how can one check this level in the water that they have access to.
What Is TDS?
TDS stands for Total Dissolved Solids and measures the electrical conductivity of water. Water has many inorganic salts dissolved in it and also some organic matter in small amounts. If an element gets dissolved in water and conducts electricity, it is called an electrolyte. This electricity is conducted due to the mobility of cations and anions, which are positive and negative ions respectively.
The elements normally found dissolved in water are sodium, calcium, potassium, and magnesium all of which are cations. The anions normally found in water are chloride, sulphate, carbonate, bicarbonate and nitrate.
TDS is measured in parts per million (ppm), which is the weight-to-weight ratio of any ion to that of water.
Permissible Range of TDS
Though different governments have approved different regulations for the TDS level of drinking water, let’s go with WHO prescribed limits. According to that, water with TDS less than 300 is excellent, while anything between 300 and 600 is considered good. If your drinking water has a TDS level between 600 and 900, then too it is fairly okay, but anything above that is a matter of concern.
If water has high TDS levels, it becomes excessively hard and unpalatable. Mineral deposition and corrosion happens.
How to Check the TDS Level?
When you research for water purifier online, a lot of results show up. To decide which one is ideal for you, you need to check the TDS level of water you are getting at home. There are various methods by which you can measure it. Let’s discuss the most common ones.
- Using Digital TDS Meter
This is the easiest method of all. You can buy a TDS meter for few hundred bucks. Just switch on the meter and immerse it to a max of 2 inches in the water for which you want to check the TDS. Stir the meter to dislodge air bubbles if any. Once the reading stabilizes on the meter, which takes few seconds, you would get to know the TDS level.
Using Filter Paper and a Scale
For measuring TDS by this conventional method, you need a sterilized beaker, evaporating dish, pipette, scale to measure, filter paper and the water sample to be tested.
First, take the weight of the empty evaporating dish in milligrams and let us call it A. Take the water to be tested in a beaker and stir it vigorously to agitate it. This is required to make the particulate matter present in it to distribute evenly. While stirring it, take 50ml water in a pipette. Pass this water through filter paper thrice. If any residue is seen on the filter paper, transfer it to the evaporating dish. Let it dry and then weigh the dish again and name it B. By subtracting B from A and substituting it in the formula [(A-B) *1000]/ml, you will get the TDS level. Use 50 in ml as we used 50ml water.
Using any of these methods, you can find the TDS present in the water in your house and decide accordingly whether you need a water purifier or not.
