Water filters are devices that help remove impurities from tap water by using a fine physical barrier, a chemical process, or a biological process to filter water and lower the presence contaminating elements. While tap water is relatively clean, thanks to processes that take place inside water treatment plants, it often only meets the minimal water quality standards from the EPA, which many experts deem too lenient. As a result, at-home water filtration systems offer a last line of protection from viruses, bacteria, chemicals, and harmful metals like lead. If you use tap water for drinking or cooking, it's always a good idea to invest in a water filter to ensure that you're getting quality, clean water.
Most water filters work through a mixture of physical and chemical filtration to remove particles and microscopic contaminants from our water. Physical filtration provides a physical barrier - kind of like a sieve - that removes larger particles from your water by straining them out. Also known as mechanical filters, this process uses anything from a basic mesh that filters out large debris to a ceramic filter which has an extremely complex pore structure for ultra-fine filtration of pathogenic organisms. Physical filtration systems usually have a micron rating which indicates how effective the filters are in terms of the size of the particles it is capable of removing. The smaller the micron rating, the finer the sieve, and the more contaminants the process removes.
Chemical filtration uses simple chemical reactions on water passing through an activated material (like carbon) to remove smaller impurities that physical filters can’t catch. The process can take place via any one of the following ways:
Reverse Osmosis: This method requires the use of filters to remove contaminants by using water pressure to force tap water through a semipermeable membrane. As the water passes through, contaminants like Lead, Mercury and Iron are left behind and flushed away. However, reverse osmosis will not remove some pesticides, solvents and metals such as Chlorine and Radon. Ion Exchange: These filters are popular in areas with hard water. They initate a chemical process that essentially releases ions like sodium and exchanges them for unwanted ions (like heavy metals) in your water. The result is softer water with a more pleasant taste, however Ion exchange is not a great choice for people with low sodium diets since it raises the sodium content of your water. Steam Distillation: This method mimics a natural process that involves heating water and cooling steam to remove contaminates. Most contaminants have a boiling point higher than water, so they’re left behind after the water turns to steam. The steam is then collected and condensed back into water. One drawback to distillation is that it also removes beneficial natural minerals from water in the process. Activated carbon: One of the most popular methods of filtration, activated carbon filters are widely used in most household water filters. Also known as absorption filters, these devices use charcoal, a very porous form of carbon, with large internal surface area that traps contaminants. Larger particles are stuck on the outside surface, removing sediment from the water. Carbon also acts like a magnet for compounds like lead and VOCs, trapping contaminants internally as the water passes through the filter. Finally, chemicals like Chlorine are reduced through a chemical reaction when water first contacts Carbon.
These methods do not work in isolation. Rather, residential filtration devices take into account the limitations of each method and use a combination of them to achieve the required level of water purity. Household water jug filters generally use mechanical, absorption and ion-exchange; inline filters use mechanical and absorption with the possible inclusion of sequestration if the filter is designed to inhibit scale; and reverse osmosis systems can utilise mechanical, absorption and reverse osmosis.
Filters can be installed at numerous points in your water delivery system. Inline filters are one of the more common applications. These directly on the water line or appliance - usually under your sink - and ensure that water passes through the filter before reaching the tap or appliance, stripping it of chlorine, odour, and bacteria. If you have a storage tank, filters can also be place on its tank's inlet and outlet to filter the water coming into your tank or leaving it. These usually take the form of drop-in filters, which sit inside specialised housings and can be frequently changed out when clogged. Gadget-specific filters ensure that appliances like coffee machines, fridges, and washing machines get municipal water at appropriate purity levels. Jugs and bottles can also come equipped with in-built water filters, as is the case with Brita. In this case, the jug is affixed with a disposable and interchangeable carbon filter that attracts and holds chlorine, and removes heavy metals like lead and copper by an ion-exchange system that attracts positively charged metals.
If you're interested in upping your at-home water game and investing in a water filter for your family, get a jump on it with a quick call to one of our local experts in Doha, Qatar, listed below.