Due to poor supply of drinking water in many cities, we are more concerned about to purity of water we drink or consume every day. The highest purity of water is obtained from the Reverse Osmosis or RO system. The RO System considerably reduces the TDS level of drinking water. The normal tds of water is very high (450-600 ppm) at some places. However the drinking water tds level as advised my many experts, should be around 50-100 ppm. Talking about packaged drinking water, TDS level has a varying range. For instance, according to a study, the TDS level in bisleri water is around 160ppm, whereas it is 12ppm for kinley water.
How water TDS is checked
Total dissolved solids (TDS) refers to the inorganic contents likes calcium, sodium, bicarbonates, etc. and some organic components which get dissolved in water. TDS is considered for freshwater and is normally used as a measure of purity for drinking water.
TDS is usually checked, by relating it to the conductivity of the water. Conductivity of a liquid depends on the behavior of the ions dissolved. There is another method called gravimetric analysis, which requires evaporating the liquid and measuring the left content, but this method is not feasible in measuring drinking water TDS level.
A TDS meter is used to measure the TDS of drinking water. TDS is measured in PPM i.e parts per million. TDS value of 1 ppm means 1 milligram dissolves solids in 1 kilogram of water. TDS meter is basically a EC meter, it measures the electrical conductivity (EC) of the water and converts it to show the TDS level of water. The electrical conductivity of water changes due to dissolves contents in it. The readings of TDS meter may involve some errors as the EC of water may increase or decrease depending upon dissolve contents.
How TDS is Controlled in Water Purifiers
Water purifiers have TDS controller installed in them which check the TDS level of the water. There are various kinds of water purifiers available nowadays and each has different methods of purifying the water. The purifiers remove microbes and thus decrease the TDS level of the water. At times, the TDS level may decrease to a very low value. This is when the water tastes bitter. Drinking water with very low TDS value is also harmful.
Thus, a TDS controller is required which measures the purified water and check if the water is in drinkable range. If the TDS of the water is low, It increases the TDS level and if high, decreases it.