World Water Week –  we call this Blue planet our home, and we all know why Earth is referred to as a blue planet, it has more water (71%) than land. However, according to National Geographics, the Earth has a mere 3% freshwater available that comes from glaciers, groundwater, lakes, rivers, and swamps combined.

It is the same freshwater that we drink.

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The quality and purity of this 3% freshwater is not distinguishable everywhere in the world. Even the taste of freshwater varies from one place to another. What changes the quality and the taste of water is the amount of TDS (Total Dissolved Solids) level it contains.

A variety of dissolved solids contaminates water. Solid particles larger than 2 microns are classified as TDS. These dissolved organic and inorganic particles are impossible to see from bare eyes. But these can make the water taste saline or sweet depending on its TDS level. 

A collection of minerals and ions dissolves in water when it passes through the river bed, pipes, channels, and different surfaces. 

Although these are not the only sources of TDS and is not the only kind of TDS, harmful chemicals released from factories, fertilisers, Calcium, Magnesium, Sodium, and Potassium cations, as well as Carbonate, Hydrogen Carbonate, Chloride, Sulphate, and Nitrate anions usually consist in water as TDS

How is TDS measured? 

The level of TDS in water is measured by a TDS metre. Though the metre can not distinguish existing TDS components in water, it can tell the exact amount of TDS at a numerical level. 

TDS level is measured as a volume of water with the unit milligrams per litre (mg/L), also called parts per million (ppm). The water, which has a TDS level of more than 1000mg/L is unsuitable for utilisation. However, the US-based Environmental Protection Agency has set the suggested highest degree of 500 milligrams per litre (mg/L).

Higher than the recommended level of TDS in water can result in the following things

 If the TDS level is above the recommended level, it can leave an unpleasant odour in water or can make the water taste bitter or rusty. This could certainly not quench your thirst. 

Initially, consumption of the water high on TDS won’t do any harm, but with the passage of time, toxic particles such as chemicals, lead, or copper are bound to damage health.

If the water used for cooking contains TDS over the recommended level, it will alter the taste of foods. Water with Higher amount of TDS usually leaves spots and stains on the surfaces of utensils. 

This does not end here, it could cause scale and rust formation in pipes and appliances, shortening their lifespan.

So, is it possible to achieve a certain recommended TDS level in water? Apparently yes.

Usually, between 50 to 150 PPM  level in water is considered excellent for drinking. 150 to 250 PPM is good for consumption, 250 to 300 PPM is generally a standard for drinking water, but anything above 1000 PPM is harmful. 

High amounts of TDS in drinking water can lead to various medical conditions, especially in children and older people since they happen to be sensitive to pollutants because their immune systems won’t be as strong and developed. 

In any case, the presence of lethal particles like lead, nitrate, cadmium, and arsenic present in water can risk serious medical issues. Nonetheless, there are several ways to reduce the level of TDS in water. 

 Reverse osmosis 

Reverse osmosis is a process in which water is passed through a synthetic membrane under high pressure. The membrane has minute microscopic pores which trap the particles bigger than 0.0001 microns while letting the smaller ones, considered safe, to pass through it. The trap Molecules of dissolved metals and salts in water are large compared to the water molecules. 

Distillation

Boiling of water to a point produces vapour. This vapour ascends to a cool surface where it is consolidated once more into the liquid form. The densely dissolved salts can’t disintegrate and hence are left behind, and the outcome that emerges is purified water. 

De-ionisation

In this cycle, water is passed through a positive and a negative cathode. The ion selective membrane empowers the positive particles to isolate from the water and move towards the negatively charged electrode. The outcome is deionised water with high purity. In any case, the water is first gone through a reverse osmosis unit to eliminate the non-ionic organic pollutants.

RO, UF, UV, or even gravity-based water purifiers are capable of filtering out the excess amount of TDS, advancing above the recommended level in the water. 

All these water purifiers have their own pros and cons. Therefore, it is advisable to check the amount of TDS in your drinking water and the capacity of purifiers in eliminating TDS from water, before buying a water purifier.