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If you draw water from your own sources, filtering it is an essential step that allows you to safely consume and use the water in your household. But do you know what types of water filtration exist, how to choose a water filter, and how to maintain it?
Drinking water filters vary according to the technologies used, filter materials, and purpose. The most common are mechanical filters and activated carbon filters.
It is important to emphasize at the outset that filtration only refers to the removal of mechanical impurities from water. Mechanical filtration can be either sieve or membrane-based. Membrane filtration is generally more effective but is not suitable for drinking water, as the membrane also captures essential substances that the body needs. This method of filtration is therefore only suitable for technical purposes, whereas for domestic filtration of drinking water, only sieve filters are used.
Chemical filtration is not filtration in the true sense of the word but rather water treatment, where undesirable chemical or organic substances are removed from the water. For these purposes, granular activated carbon is most commonly used, which, thanks to its surface and sorption properties, can capture a wide range of harmful substances dissolved in water—from heavy metals to chlorine and other chemicals, as well as viruses and bacteria. The carbon absorbs or captures these substances and organisms on its surface. Additionally, it removes unpleasant odors from the water and improves its taste, but beware, it is not a full substitute for water disinfection. Besides carbon, a wide range of other synthetic granules are also used for water treatment.
Most people are well aware of the risks associated with microbial and chemical contamination of water, but the risks of solid particles are less known. Although small particles in water do not pose a serious health risk to humans, they can subtly damage pipes and appliances, which can then suddenly fail. Mechanical impurities disrupt the internal surfaces of pipes, increasing the risk of limescale and cracks. They also clog appliances such as washing machines and dishwashers.
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Mechanical water filtration extends the lifespan of pipes and appliances.
Water with mechanical impurities does not necessarily appear visibly cloudy, and often, an analysis of the water reveals an excessive content of impurities. Mechanical filtration of well water is therefore a fundamental component of all domestic waterworks. It should be used not only for drinking water but also for utility water and water in heating systems.
Besides households, mechanical water filtration is also used in agriculture (irrigation water) and industry (cooling and process water), where it ensures the reliability of technical equipment.
In the case of mechanical water filtration, a water filter with a fine sieve is installed on the pipe through which the water flows. The sieves are usually made from durable polymer fibers. The filter captures impurities, allowing only clean water without mechanical particles, known as filtrate, to flow through.
The basic parameter when choosing a mechanical filter is the fineness of the sieve. This is measured in micrometres or microns (symbol μm) and determines the size of impurities the filter can capture. One micron is one-thousandth of a millimetre, and for household filters, sieve fineness of 10-100 microns is usually used.
The fineness of the sieve should correspond to the actual size of unwanted impurities revealed by the water analysis. Many people believe that the denser the sieve, the more effective the water cleaning will be. However, this is a misconception. A sieve that is too dense causes lower water flow and more frequent cleaning needs. Moreover, if the sieve is clogged, it captures even smaller impurities and clogs more quickly.
Fibrous and elastic particles are problematic in this regard, as it is not entirely clear what sieve density is required, since their passage through the sieve is largely determined by water pressure and other parameters.
As we have already mentioned, the best results in a household are achieved by combining a sieve and carbon water filter, which can be connected into one system. In the case of very contaminated water, it is advisable to include a so-called pre-filter in the combined filter, i.e., a water filter with a lower sieve density. This captures the largest impurities, thereby making the filtration process more efficient, extending the lifespan of the entire filtration system, and reducing the need for cleaning and maintenance.
In the filtration system, the pre-filter (if installed) is always first, followed by a fine sieve filter. Further domestic water treatment units operating on chemical reactions, such as the mentioned carbon water filter or hard water filter, are then arranged. Correct sequencing is very important, as mechanical impurities could degrade the carbon granulate.
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SYR Ratio backwash filter.
To ensure that drinking water filters function properly and do not become clogged (thus blocking the water supply system), it is necessary to regularly clean the sieve by backwashing. Modern filters with automatic backwash function and control units are completely maintenance-free in this regard—they can assess the degree of sieve clogging, determine the need for backwashing, and then automatically perform the backwash without your intervention.
Manual backwashing is more complex, and you must monitor the condition of the sieve yourself. The entire filter needs to be dismantled, and the sieve gently rinsed under running water until it is completely clean. A semi-automatic solution is a water filter with a backwash function. In this case, you do not need to dismantle the filter; the backwash is initiated by opening the backwash valve, from which water and impurities from the sieve then flow out.
In filters with activated carbon, regular replacement of the filter cartridge is necessary, as it has a limited lifespan of about 6 months. After its lifespan has expired, the carbon loses its sorption properties and cannot effectively remove unwanted substances from the water.
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