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There are many varieties of water filters used at homes. However, all of them rely on few technologies to remove contaminants. The quality of water produced by a water filter is not dependent on the technology used. It is, therefore, advisable to choose one that units the needs and circumstances
1. Activated Carbon Filters
Also known as pre-filters or carbon filters, they remove large particles like silt and sediments from the water. Carbon filters work by chemically bonding with water contaminants and removing them. The effectiveness of carbon filters differ from one to the other based on the contaminants removed. Some of them remove chlorine and improve the odor and taste of water. Others clean water by removing the several contaminants such as mercury, asbestos, volatile organic compounds, and lead. The major limitation with activated carbon filters is that they cannot remove inorganic pollutants such as nitrate, chromium, arsenic, and percolates. Activated carbon filters come in two different forms, granulated activated carbon, and carbon block.
2. Granulate Activated Carbon
This is a form of activated carbon filters. It contains activated carbon occurring in the form of fine grains. Since they have a smaller surface area than carbon block, they are considered less effective. The effectiveness with which they filter water is also dependent on the speed at which water flows through.
3. Carbon Block
Another form of activated carbon filters, carbon block filters contain activated carbon in a pulverized form. The pulverized carbon is put under high pressure to form carbon blocks. They have more surface area than granulate activated carbon which makes them more effective.
4. Ceramic Filters
These filters are made of a material that has very small holes. These holes filter water by blocking solid contaminants such as sediments and cysts. However, they do not filter the chemicals dissolved in water.
5. Reverse Osmosis
With reverse osmosis, water is pushed through a semi-permeable membrane by use of high pressure. The semi-permeable membrane then blocks particles which are larger than the molecules of water. It is very effective in removing contaminants which are not removed by activated carbon such as inorganic pollutants such as nitrate, chromium, arsenic, and percolate. Contaminants that are not removed by reverse osmosis include volatile organic chemicals, chlorine, and trihalomethanes. However, most reverse osmosis systems come equipped with an activated carbon component for filtering out the other contaminants. Reverse osmosis systems are best suited for cooking and drinking water since they waste a lot of water. They can use up to 20 times the volume of water than they produce.
Deionization filters rely on an ion exchange process to facilitate the removal of electronically charged molecules and mineral salts. Nonionic contaminants such as trihalomethanes and microorganisms cannot be removed through this process.
7. Water softeners
These filters also rely on an ion exchange process which lowers the levels of magnesium, calcium, some forms of radium and barium. Build up of calcium and magnesium can create problems in plumbing fixtures. Treated water is known to contain high levels of sodium since the calcium and magnesium are replaced with sodium during the softening process. Softened water is not suitable for watering gardens and plants.
In this process, water is heated at high temperatures, vaporizes and the steam produced is later condensed into water. This process is effective in removing minerals, viruses, many bacteria and chemicals that have boiled at higher temperatures than water. Volatile organic chemicals, trihalomethanes and chlorine are not removed by distillation.
This is technology that uses ultraviolet radiation to kill microorganisms and bacteria. Ultraviolet water filters do not remove contaminants that are chemical in nature.
10. Mechanical filters
These are also designed like ceramic filters with small holes. These small holes filter out large contaminants such as sediments and cysts. They are not used in standalone but combined with other filters to make the filtration process more effective.
11. Ion exchange
In this type of filter, water is passed over a resin material. The undesirable ions in the water are replaced with those which are desirable and harmless. A common application of ion exchange filtration process is in water softening where sodium and magnesium are replaced with sodium. These filters are known to have high maintenance since the resins must be regularly replaced with ones that are ionized.
Water filters apply different technologies to achieve the filtration of water. The main difference among all of them is the type of contaminants removed. It is, therefore, advisable to choose the one that suits the needs.