Water purification techniques are the methods used to make water safe for drinking, cooking and other uses. There are several types of water purification techniques that can be used in homes, restaurants and public places.
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The most common water purification techniques include:
Boiling – Boiling water is one of the simplest and most effective ways of purifying water. Boiling kills all bacteria present in water, making it safe for drinking. However, boiling doesn’t remove heavy metals such as lead or copper from the water.
Distillation – Distillation involves boiling water and then collecting the steam which carries away harmful chemicals like chlorine and iodine. This steam is then condensed back into clean drinking water. This process can remove almost all impurities from water but it’s not very efficient when it comes to removing viruses or parasites like Giardia lamblia or Cryptosporidium parvum from water
Ultraviolet light – Ultraviolet light kills bacteria by destroying their DNA through oxidation reactions. This process also works on viruses and parasites like giardia lamblia or cryptosporidium parvum
What is TDS?
The total dissolved solids (TDS) refers to the quantity of dissolved substances in water. It is measured in terms of parts per million (ppm). Groundwater has a high TDS since it is a major source for drinking water supply.
TDS is the sum of all ions and molecules present in the water. The main constituents are:
– Potassium : 3.0 mg/L
– Magnesium : 1.5 mg/L
– Sodium : 0.2 mg/L
– Calcium : 0.1 mg/L
– Magnesium : 1.5 mg/L
– Sulphate : 30 mg/L
National Green Tribunal’s (NGT) Take on RO Purifiers
The National Green Tribunal has directed the Ministry of Environment and Forests (MoEF) to issue a notification banning best RO purifier where total dissolved solids (TDS) in water are below 500 milligrams per litre.
The matter is currently sub judice and no final legislation has yet been passed to this effect.
The petition filed by an NGO called “FRIENDS” in Delhi, stated that in light of wastage of water by RO technology and adverse health effects of drinking water with a low TDS devoid of certain essential minerals, RO water purifiers be banned in areas where the TDS of water is below 500 mg/litre.
In response to this petition, the NGT has ruled that in light of wastage of water by RO technology and adverse health effects of drinking water with a low TDS devoid of certain essential minerals, RO water purifiers be banned in areas where the TDS of water is below 500 mg/litre.
How to Select the Best Water Purifier for Home Use?
Water quality varies from place to place, and there are many factors that influence it. The most important factor is whether your water is surface water (from rivers and lakes), groundwater (from borewells) or a mixture of both.
Different types of water purifiers – which one is suitable for your water?
Is your water surface water (from rivers and lakes) which has been supplied by the municipality or is it groundwater (from borewells, supplied by tankers) or a mixture of both?
If it is surface water, supplied by the municipal corporation, chances are that the TDS (dissolved impurities) are low and you need to only protect yourself from microbiological impurities like bacteria and viruses. However, if your water is groundwater supplied by tankers, there may be a higher level of dissolved impurities, altering the taste of the water, and at higher levels may affect your long term health.
The minimum TDS for drinking water is 500 ppm (parts per million). As a thumb rule, if you get groundwater, check the TDS with a simple TDS meter. If your TDS is above 500 ppm, then choosing an RO water purifier may be beneficial. If the TDS is lower than 500 ppm, then a well-designed UV purifier will be effective in purifying the water. If you get a mixture of both – ground and surface water then an “intelligent” purifier with a sensing purification technology will be effective.