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Buying Guide for Water Purifiers in India

Common chemical contaminants in water

On this page we discuss about dissolved chemicals in water and what the chemicals in water health effects are. Chemicals that are dissolved in water which cannot be removed by simple filtration. Some salts dissolved in water are not toxic in small quantities, but there is a limit which can be tolerated by our bodies. For example, Sodium Chloride or the common salt, is being used by us daily to flavour food, but that does not mean that we can drink sea water which contain a high percentage of sodium chloride or salt. So the individual salts, dissolved in the water, may not be toxic in small quantities, but there is an upper limit or Maximum Contaminant Levels (MCL) to these dissolved solids in our drinking water.

We give below the most common chemical contaminants found in water. Some of these also appear as harmful chemicals in tap water in India. Each of these chemical contaminants is described in detail including how the chemical pollution in drinking water effects our health and the quality of water.

Physical measurement of water quality parameters

The most important water quality parameters are TDS and pH. TDS measures the total quantity of dissolved solids or chemicals in water. pH is a measure of how Acidic or Alkaline water is. Both these important water quality parameters depend on the amount and type of Chemicals dissolved in the water. More on TDS and pH explained in detail in our dedicated page

Dangerous heavy metals in drinking water

Salts of Arsenic, Barium, Cadmium, Chromium-6, Lead, Mercury, Selenium, and Silver are regulated by the EPA and almost all drinking water standards of the world including the Indian Water Quality Standards for drinking water. These water standards assign a maximum contaminant level MCL, usually expressed in parts per billion, which is an extremely minute amount beyond the measuring capabilities of most water testing labs.

Iron in drinking water

Iron causes a rusty or metallic taste in water and it can also stain clothes. Iron in water is not harmful to human health, but water containing iron salts can have a bad taste and may be discoloured. Iron and manganese occur naturally and most ground water has some amount of dissolved iron and manganese. Aeration (the addition of air to the water), Green Sand filtration, chlorination, and dosing hydrogen peroxide or Potassium permanganate are some of the ways to get rid of Iron. RO will remove dissolved Iron and Manganese.

Fluorides in drinking water

Fluorides are chemicals that contain the element fluorine. Fluorides occur in many water sources naturally. In some countries fluorides are added to drinking water as a health supplement for the protection of teeth and bones. Fluoride in water in very small quantities, about 1 to 1.5 mg per Liter or ppm - parts per million, is beneficial to health, but any excess is not good for health.

Many toothpaste manufacturers add it in the toothpaste to protect the teeth against cavities. The Indian Drinking Water Standards BIS-10500 has set the MCL (Maximum Contaminant Level) of Fluorides in water as 1.5 mg per Liter or ppm. Excess fluorides in water can have harmful effects ranging from discoloration or pitting of teeth to bone and skeletal damage. RO water filter purifier for removing Fluorides in water is the most effective treatment.

Nitrates in drinking water

The most common way Nitrates, Nitrites and Ammonia gets into our water sources, is due to the leakage or seepage of fertilizers or farm and animal wastes into the ground water sources. Nitrates in water are especially dangerous to infants under 6 months, causing 'methemoglobinemia' or the ‘blue baby syndrome’ due to the infant’s blood not being able to carry enough Oxygen from their lungs to their body. Adults may also be affected by nitrates and nitrites in water due to the formation of chemicals called nitrosamine in the digestive tract. The Indian Drinking Water Standards BIS-10500 has set a maximum limit for Nitrates in water as 45 mg per Liter or ppm measured as NO3 or Nitrate. RO water filter purifier for removing Nitrates in water is the most effective treatment.

Aluminium in drinking water

Aluminum in water is not regulated but recent research has revealed a link between aluminum intake and possible adverse effects on human health and its possible role as a cause of Alzheimer's disease and Parkinson's disease. With these doubts being raised it will be a wise decision not use Aluminum cooking vessels. In this respect we must also point out that almost universally, in all municipal size plants, Aluminium Sulphate or Alum is used as a coagulating agent for the sedimentation of suspended solids. For sure some of this aluminum will be present in the municipal supplied waters. So an RO water purifier, which can remove Aluminium salts, is the safest bet against all water problems. Aluminium is not in the regulated lists of WHO, EPA, BIS 10500, etc., but in our opinion, it should be.

RADON or Radioactive drinking water

Certain minerals are radioactive and people who drink water containing it over many years may have an increased risk of getting cancer. Radon is naturally occurring and ground waters in some areas of India may be contaminated with it. The only way to be certain is to get the ground or well water tested. Activated Carbon filters, which are included in almost all home RO water purifiers, are very good for the removal of Radon from water supplies and it is the most common way to reduce Radon in the water. RO water filter purifier for removing Radons or radio active materials in water is the most effective treatment.

Organic Chemicals in drinking water

Organic compounds in water adversely affects the quality of water. It can cause bad taste and smell in drinking water. Some of the Organic Chemicals in water can cause cancer (Carcinogenic) and are very harmful to human beings. The usual organic contaminants of water are Pesticides, fertilisers, reaction compounds of Chlorine with organic compounds, etc.

Chlorine which is used to keep water free of bacteria, causes another problem by reacting with some organic material in the water to form harmful chemicals like Chloroform, Trimethohalanes (TMHs), Haloacetic Acids (HAA), Trihalomethanes (THMs) and other "Disinfection by-products" (DBPs) or "Chlorination Disinfection by-products" (CBPs), which are all environmental pollutants and many considered 'carcinogenic', or suspected of causing Cancer. Activated Carbon filters, which are present in domestic RO water purifiers, are very effective in getting rid of such impurities in water which normally occurs in minute quantities.

Measurement of Organic Chemicals in Water

Measurement of Organic Compounds in Water is expressed as Total Organic Carbon (TOC). TOC measures the difference between total carbon and inorganic carbon in a water sample. Volatile Organic Carbon (VOC), Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), Dissolved Oxygen, etc. are some of the other popular Water purity indicators or parameters. Most of these parameters like BOC, COD, etc. are used in waste water recycling plants and are beyond the scope of discussion on this website.

Problems caused by chemicals in water

Some of the parameters or indicators for the quality of water due to dissolved chemicals are listed below. Further down we give a brief introduction of what each of these terms of water parameters mean.

pH of Water meaning

pH value is a measure of how acidic or alkaline water is. The pH measures the acidity or alkalinity of water from a scale of 1 to 14. The mid point pH value of 7 is a neutral pH, meaning water is neither acidic nor alkaline. pH Value lower than 7 is acidic water, the lesser the number the more acidic the water is. Similarly pH value of more than 7 indicates alkaline water and the higher the figure the more alkaline the water is. The pH scale is not a linear scale but a logarithmic scale, which means that it is indicating a power to 10, which basically means that an increase or decrease in value of 1 indicates a 10 times stronger or dilute acid or alkali. Meaning of pH is explained in more detail in our page about pH

Total Alkalinity

Alkalinity is a property of water defined as the capacity of water to neutralize acid. Total alkalinity is a measure of the amount of acid required to neutralize the water pH to 7 or to reach a specific pH usually between 4.3 to 4.8 and this pH has to be mentioned when a measure of the Total Alkalinity is mentioned.

Acidity of Water

Acidity of water can be defined as the amount of standard Sodium Hydroxide (NaOH) required to neutralise or to change the pH of the water from 4.3 to a pH of 8.3. Acidity of water is an important measure to know how corrosive or the corrosiveness of water on reinforcement steel in concrete for example.

Hardness in Water, is it bad for health

Hardness in water is caused by dissolved salts of Calcium and Magnesium. How Hard the water is depends on the concentration of Calcium and Magnesium ions (Ca2+ and Mg2+). Hard water is not harmful to health as long as the TDS is within the limits. Hard water can be ‘softened’ by replacing the Calcium and Magnesium with Sodium in an Ion Exchange Water Softener. For washing clothes, treating the hard water with Sodium Carbonate or washing soda, reduces many of its problems. Water Softener, Nanofiltration and RO make hard water soft.

Hardness of water affects the pH of water. Soft water is usually more acidic and will have low pH. Hard water water on the other hand has dissolved Alkaline chemicals of Calcium, Magnesium, etc. which makes the water alkaline and therefore raises its pH. A measure of Hardness is stated as an equivalent of so much CaCO3 in mg/L of CaCO3. Hardness can also be caused by other salts like salts of iron. Water is classified as Soft Water when mg/L of CaCO3 is between 0 to 60, slightly Hard Water is 61 to 120 mg/L of CaCO3, Hard Water is 121 to 180 mg/L of CaCO3 and it is very Hard Water when the mg/L of CaCO3 is over 181. We also have a dedicated More on Hardness of water from page on Hard Water.

Total Dissolved Solids - TDS

Total dissolved solids (TDS) measures the total dissolved salts in mg contained in a Liter of water. To Test TDS in a lab, a sample of water is filtered through very fine filters to remove all suspended solids. Then the quantity of water sample is accurately weighed and then evaporated to dryness leaving behind all dissolved salts. The solid matter obtained from the water sample after evaporation is weighed. The TDS is then calculated using the weight of the dry salts and initial weight of the sample water and the resultant TDS expressed as mg/L.

TDS hand held meters are available to easily find an approximate value of TDS. These meters measure the electrical conductivity of the water sample and then converts into TDS mg/L measurement using conversion factors. For More of TDS visit our page about Water TDS and Electrical Conductivity.

Maximum Contaminant Levels (MCL) from EPA website

A full list of all water contaminants, Treatment Techniques to remove them, their MCLs or Maximum Contaminant Levels, and how they harm your health is available from the EPA website

How to remove chemicals from water

Ordinary filtration cannot remove chemicals from water. Distillation of the water is one method to remove salts from water, but this requires a lot of electricity or fuel and is not practical for domestic use. The other most common way to get rid of dissolved solids is by a water purification process known as Reverse Osmosis or RO which is described in detail in a separate page on RO water purification in our site.

Best way to buy Water Purifiers in India

The best way to buy Water Purifiers in India is to first look at all models of Water Purifiers available online at the leading online Retailers in India. For example on the online webpage of All Water Purifiers available in India on Amazon.in, you will find the full range of Indian Water Purifiers complete with their best discounted price and full specifications. This is great information, and you can decide on which model of water purifier to buy. With the model of water purifier you want to buy finalised, you can go to local shops to try and find the model of water purifier you have chosen and see if you can get at similar price of that at Amazon.in. In most cases the price from Amazon will be cheaper, because they buy in bulk from the manufacturers direct and they sell huge volumes because they are the world's largest and most trusted online retailer. If you buy from Amazon, they will arrange to have the water purifier installed in your house, usually free of charge.

Warranty and other facilities offered through Amazon are usually better than what you can get from local agents of water purifiers.

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