What is the indicator of life on any planet?
When we say, we are exploring possibilities of life on Mars, what is it that astronomers and scientists are searching for? The answer to both the questions is ‘Water’.
Yes, water is as essential to life as air. One cannot imagine any life form without water. Fortunately, our Earth is blessed with sufficient water to take care of life in the present as well as the future generations.
Having said that, are we ensuring that the future generation has access to clean and pure water to drink?
The answer to this question is a NO as well as a YES. NO, because the release of human and industrial waste is the primary cause of water pollution in the world.
YES, because we have invented some of the best water purifying machines to eliminate the impurities that ironically we are responsible for introducing in the first place.
Table of Contents
- Different sources of water
- Sources of water pollution
- Types of impurities in drinking water
- The acceptable TDS levels
- Types of water purifiers available in the market
- Water purification technology explained in brief
- Electro Adsorption Technology
- Reverse Osmosis
- Which filter to buy?
- Factors to consider while buying water purifiers
- Understand the drawbacks of the RO water purifiers
- Final Words – Wrapping it up
Different sources of water
Sources of water pollution
The rivers are pristine when they descend from the melting snow caps. As they find their way to the plains, these rivers gather salts and minerals from the rocks and sand.
All these impurities find their way into the human settlements thereby causing water-borne diseases like cholera, dysentery, etc. Therefore, there is an urgent need to purify the water resources before consuming them.
This is the concept behind the functioning of the various water purifiers. You have different methods of purification based on the level of impurities and TDS in water. We shall discuss each type of filter for the benefit of all.
Types of impurities in drinking water
As discussed earlier, you have various kinds of natural salts finding their way into your kitchen through the water resources. Similarly, groundwater also contains a lot of minerals and salts in its natural form.
Eliminating these wastes requires the use of modern technology like Reverse Osmosis (RO), Ultraviolet purification (UV), and Ultra-filtration methods (UF). The modern water purifiers employ any or all of these methods of purification.
The acceptable TDS levels
We have seen the concept of TDS in water. We know how it manages to find its way into the water resources. In a way, our body needs some of these minerals and salts for its healthy growth.
Hence, one should ensure not to eliminate them completely from the drinking water. Now, the question arises as to what the acceptable TDS levels are.
Note that these levels are purely indicative. In the normal course, you will find ground level as well as other water sources having TDS levels below 900.
As per the above table, it should be fair for consumption directly. Is it true? Unfortunately, the answer is NO. The level of concentration of individual elements of TDS is more important than the general TDS value.
It can happen that you might have water with TDS levels in the range of 300. But, the water can have a high concentration of arsenic or mercury and a lower concentration of other salts.
Under such circumstances, is the water safe? You have the answer at the tip of your tongue. This water is certainly not palatable. Hence, you need water purifiers to eliminate these impurities completely.
Types of water purifiers available in the market
We shall start with the simplest kind of water purifier and move on to the ones that use modern technology.
These are the simplest form of filters available in the market. In the olden days, people did not have access to much technology. They used simple white pieces of cloth to trap the dirt and suspended particles and obtain clear water.
This is the inspiration behind these simple membrane filters. You have these small contraptions that you attach to the tap and have access to filtered water straightaway. These contraptions contain a tiny wire mesh that is capable of trapping the sediments and other insoluble particles.
These filters are used in areas where you expect the least water pollution such as the hilly areas near the sources of rivers. You get pure water directly from the rivers that flow past the areas, but there are chances of suspended organic and inorganic impurities. These wire meshes can help in eliminating such impurities.
The faucet mounted water purifiers are one of the most convenient water purifiers available in the market today. They usually comprise of a sediment and activated carbon filter that can cater to the purification of water with lower levels of TDS.
The gravity-based water purifier is an advanced version of the faucet mounted water purifier. The advantage of having such a water filter is that it has a storage tank capable of storing enough water for the entire family.
The gravity-based water purifiers available in the market today comprise of two separate tanks, one for the input water and the other for the output water/storage. These filters work best in areas where there is a low level of bacterial contamination. Similarly, these filters are not suitable for areas having water with high level of TDS.
Reverse Osmosis is one of the best water purification techniques today. This technique can eliminate TDS up to 90%. These filters are capable of removing pesticide residue and heavy metal impurities like arsenic, iron, mercury, and lead.
They are also capable of destroying bacteria and viruses. These RO filters usually are complemented by UV compartments and UF membranes. They assist in eliminating these bacteria and other microorganisms completely. We shall discuss the various aspects of the RO water purification process separately.
The Electro Adsorption Technology (EAT) is another popular water purification technology. This is equivalent to the RO process as far as quality of the output water is concerned. However, this technology has an advantage over the RO process in the sense that it does not waste water.
But, there is a drawback as well. This process works best only when the input water source has TDS content less than 500. RO water purifiers can handle water with TDS levels as high as 2000.
Water purification technology explained in brief
We have seen four different types of water purifiers. Each of these water purifiers works on a specific technology. There is not much to explain the working of the membrane filters, faucet mounted and gravity based water filters. Let us concentrate on EAT filters and RO + UV + UF filtration processes.
Electro Adsorption Technology
This technology involves a five-stage purification process. They are as follows.
This is a universally popular method.
You are also able to eliminate TDS up to 90% using this process. The RO water filters work on a 5 or 6-stage purification depending on the configuration of the water purifier.
The sediment filter
This is an optional arrangement. Usually, you have this filter fitted outside the machine. This filter takes care of the visible suspended particles and larger impurities. This filter enhances the life of the RO membrane as it eliminates the larger particles and does not allow them to enter the machine.
You need not use this sediment filter when the input source of water is clear, especially the water treated by the municipalities before distribution to the households.
Pre-activated carbon filters
The pre-activated carbon filter removes organic and the other volatile compounds from the water that usually give the water its bad odour.
Reverse Osmosis mechanism
The next stage of filtration is the RO filtration. In the normal course, the water does not have a tendency to move from a higher concentration to lower concentration when passing through a semipermeable membrane.
Hence, you need to use a pump to push the water through the RO membrane. This is the principle of reverse osmosis. The RO membrane removes all kinds of impurities in the water such as TDS, pesticide residue, heavy metal impurities like mercury, lead, arsenic, and biological impurities like bacteria, viruses, and microorganisms.
This water is separated into two parts, the impure part that goes down the drain and the pure and filtered water that passes through the UV chamber for the next stage of filtration.
The pure water obtained through RO filtration contains traces of bacteria and viruses. This is because the RO membrane cannot filter out impurities with molecular weight less than 20. It cannot eliminate monovalent ions like sodium, etc. Hence, this water now passes through the UV chamber where the ultraviolet radiation kills all microorganisms and bacteria thereby making the water 100% safe to drink.
The resultant water now passes through an Ultrafiltration membrane to remove traces of residual impurities. This filtration membrane contains minute pores that trap any impurities that might have escaped elimination in the RO process.
The Post-activated Carbon filter
This filter is responsible for removing the volatile organic compounds that cause the bad odour of the pure water flowing out of the RO water purifier. This improves the taste of water.
The TDS Controller
The water that comes out of the RO water purifier is pure and healthy. But, the RO mechanism eliminates almost all the TDS from the water. In fact, it removes more than 90% of TDS from the input source. This includes the good and healthy salts like calcium and magnesium, etc. These salts and minerals are necessary for the overall growth of the body.
The TDS controller solves this issue by separating the input water into two parts, A and B. Part A goes through the RO membrane whereas Part B passes through the UV / UF membrane that does not remove the TDS but kills the microorganisms.
The TDS controller then selectively mixes this water with the RO purified water thereby increasing the TDS levels and increasing the pH value of the water.
The disadvantage of the TDS controller is that it releases a part of the input water into the RO purified water thereby providing an opportunity for contaminating the RO purified water. The mineralizer releases the appropriate minerals lost during the RO purification process alone. This replenishes the mineral content of the water and thus improves the quality of output water.
Which filter to buy?
You have seen the functions of different types of water filters, but the principal question remains unanswered. Which type of filter is best suited for your home? This depends on the quality of water you have as the water source.
Let us now look at the various sources of water and see the normal kinds of impurities associated with the particular source. This will enable you to decide which water purifier to choose.
|TDS Level of Input water source||Is the water muddy||Is there a presence of biological impurities||An ideal choice of water purifier|
|Below 300 ppm||No||No||Gravity-based purifiers and faucet mounted water filters are the best suited for such water|
|Below 300 ppm||No||Yes||The Ultraviolet filtration is the best solution under such circumstances as it can eliminate the bacteria and other microorganisms|
|Below 300 ppm||Yes||No||In the absence of TDS and biological impurities, you can opt for a UF filter to take care of the minute soil impurities|
|Below 300 ppm||Yes||Yes||The best machines are the UV + UF or the EAT machines|
|Over 300 ppm||No||No||As the TDS levels are above 300 ppm, you should be using the RO water purifiers|
|Over 300 ppm||No||Yes||The ideal machines are the combination of RO and UV|
|Over 300 ppm||Yes||No||The RO + UF combination should work fine because of the absence of biological impurities. To be safe, you can also opt for the RO + UV + UF water filters|
|Over 300 ppm||Yes||Yes||Invariably, you should for RO + UV + UF water purifiers.|
Factors to consider while buying water purifiers
Now, you have a clear idea about the nature of impurities in the water. You have an as to which water purifier to choose to tackle the kind of impurities. You should always conduct the test of the water source at your house before deciding the type of water purifier to opt for.
Understand the drawbacks of the RO water purifiers
The RO water purifiers employ the best water purification techniques. However, they have a major drawback in the sense that they waste a lot of water. In fact, they waste more than 50% of the input water. In this era of water shortage, this is a criminal wastage.
The best alternatives are the EAT filters. However, you will not be able to use the EAT filters when the TDS value of the input water is less than 500 ppm.
You have uses for the RO wastewater. However, the water that comes out as the wastewater contains a high proportion of TDS. Therefore, there is a need to dilute the water before using it to water your plants, cleaning the floors, etc. Also, Have a look at 12 simple ways you can save water in everyday life.
Final Words – Wrapping it up
This buying guide should make your job of purchasing your favourite water purifier easy. We have touched upon all the aspects of water pollution and the nature of water filtration technologies available in the market today.
The quality of source water plays an important part in the choice of your water purifier. Choose the right one and make the lives of your family better. You have a lot of good brands available in the market. The most common and popular brands of water purifiers available in India are Kent RO, Pureit, Bluestar, LivPure, LG and Aquaguard.
Compare these water purifiers and choose the one best suited for your family. The availability of service centres is a very important aspect. The manufacturers usually give a one-year manufacturer warranty. Subsequently, you need to enter into an Annual Maintenance Contract with the authorised service centre of the company.
Replace the filters on time. Use genuine spare parts as spurious parts can damage your purifier. Thus, we end our discussion on the Water purifier buying guide. We trust this guide will be useful to you.