Type
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Jug. Filter in the form of a jug, divided into two halves. Water is poured into the upper half, which looks like a funnel, which under its own weight passes through the filter cartridge to the lower part. Such devices are simple in design and use, as well as low cost. On the other hand, their productivity is low, the capacity usually does not exceed 2 – 3 L, and each time such a filter needs to be filled manually. For an ordinary kitchen for a family of 3–4 people, these shortcomings are not critical, but for large volumes of cooking with intensive water consumption, the filter jug is poorly suited.
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Nozzle on the tap. As the name implies, filters of this type are designed to be installed directly on the spout of a water tap, from the outside. They are easy to connect and use, and in a certain sense more convenient than jugs, because they do not require filling — filtration begins immediately when the tap is opened. Their resource and productivity are also usually higher; in addition, it is worth highlighting the low cost and small size that allowing you to carry the filter with you. Thanks to the latter, among such models there are options that can be installed on a bottle and used as travel filters (see below). The main disadvantages of nozzles are low productivity, as well as the need for regular connection and disconnection, which leads to rapid wear of the attachment.
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...href="/list/219/pr-10338/">Tabletop. Filters of this variety are separate devices that are installed on the kitchen table (or other suitable surface). They are usually connected to a tap (see "Connection") using a flexible pipe. Such filters are less transportable than the nozzles described above, and are designed for permanent installation in one place. On the other hand, their productivity and resource are usually much higher. An obligatory element in the design of table filters is their own tap (see "Tap").
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Under the sink. Filters designed to be placed under the sink. When installed, they are connected to the water supply (see "Connection"), and a separate tap is brought out to supply filtered water (usually next to the main kitchen tap, but in fact it can be installed anywhere). Such filters usually have a fairly high performance and a good degree of filtration, they are useful for constantly providing the kitchen with filtered water, including for drinking. Of the shortcomings, it is worth noting the difficulty in installation — it requires the participation of a specialist.
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Main (mesh). Main filters are called filters designed to be inserted directly into the water supply system — for example, at the entrance to an apartment. Accordingly, one of the characteristic features of such models is high performance. Mesh — the simplest kind of main filters, equipped with filter elements in the form of a fine mesh, as the name implies. They purify water only from mechanical impurities and are used mainly as a preliminary stage of purification. From models with a cartridge (see below), which can also be used for purely mechanical filtration, models with a mesh are reusable: usually the design provides for the possibility of washing the mesh, restoring its original state.
— Main (with a cartridge). Main filters (see above), which provide the use of replaceable cartridges and are equipped with the appropriate cartridges. Such a design provides more opportunities than mesh models, main filters with a cartridge are capable of providing different types of filtration, including multi-stage cleaning. And the presence of a cartridge in the kit allows you to use the filter right out of the box, without buying additional accessories. At the same time, "native" filter elements are not always optimal, and sometimes a model without a cartridge is more preferable (see below).
— Main (without cartridge). Main filters (see above), which provide the use of replaceable cartridges, but are not equipped with such cartridges. This configuration has its advantages: although the purchase of filter elements requires additional time and money, but you can choose cartridges at your discretion, without relying on the choice of the manufacturer. Sometimes it is easier to collect a filter from a housing and individual filter elements than to buy a ready-made solution.
— Pre-filter. This category includes pre-filters, which are installed not at the entrance to the apartment (as main ones, see above), but in front of a separate household unit, usually a washing machine or dishwasher. Such devices have good performance and are often equipped with water softening systems to prevent limescale formation. The degree of purification in them is relatively low, but this is usually quite enough — since the water in this case is used not for food, but for technical purposes.
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Tourist. Filters designed for use in tourist trips. A common feature of all such models is their small size, which allows you to easily carry the device with you in a backpack or even a pocket. But the design of such a filter may be different. So, some models are containers with filter lids, others are nozzles put on a plastic bottle or other similar container; there are tourist models in the form of a pump capable of pumping water from a stream, lake or other natural reservoir, etc. It makes little sense to buy such a filter for home use, but for “being far from civilization” it may turn out to be simply irreplaceable.
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Cleaning and softening system. Devices designed not only for cleaning, but also for softening water — removing hardness salts and/or dissolved ferrous from it. "Hard" water is undesirable for home use: in particular, it reduces the effectiveness of detergents and leads to the formation of scale in kettles, on heating elements of washing machines, etc. Cleaning and softening systems are divided into two types: actually softeners and iron removers. The first variety uses a special ion exchange resin that traps hardness salt ions (calcium and magnesium) and replaces them with "soft" sodium ions. Such resin must be periodically restored. In iron removers, in turn, a special catalyst is used that oxidizes soluble ferrous to insoluble ferrous — and it is already filtered out mechanically. To which particular variety this or that system belongs — it is worth specifying separately.
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Magnetic. A special kind of main filter installed to the pipeline. However, due to its small throughput, it is not intended for full-fledged water supply, but for connection to household devices, whether it is a boiler, a washing machine or a dishwasher. The main function of these filters is water softeners, which prevents plaque and buildups, it is accordingly prolongs the life of the equipment.
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For shower. Models of filters for installation together with a shower head or in front of a hose. Made in a compact size and have a connecting thread for the hose. This solution will help purify the water (only for one connection point) and get rid of clogged openings in the shower head, because the plaque from contaminated water will be much less.
Purpose
In this case is implied the temperature of the water for which the filter is designed. This parameter is directly related to the maximum operating temperature (see below). In general, modern filters fall into two main categories:
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For cold water. Exactly this purpose that most models today have, regardless of type. This is due to two points: firstly, cold water has to be filtered more often than hot water, and secondly, filter elements for such a temperature are simpler and cheaper. The temperature limit of cold water is usually held at around 40 °C.
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For hot water. Filters designed for connection to hot water systems.
When choosing a filter for its intended purpose, note that the use of “cold” filters with hot water should never be allowed. On the one hand, hot water usually has more impurities than cold water, which reduces cartridge life and cleaning efficiency. On the other hand, high temperature itself is an abnormal mode for filter materials, and instead of water purification, the opposite effect may even occur — the release of harmful substances from the cartridge. Therefore, for such cases, only filters designed for the corresponding temperatures should be selected.
On the other hand, the use of "hot" filters with cold water is quite acceptable — most of these models provide this possibility in case the hot water supply is turned off. However, for cons
...tant work with cold water, it does not make sense to purchase such a filter, if only because it will cost more than the “usual” one.Number of flasks
The number of flasks in the filter makes it clear how many
water cartridges can be installed in it. For a filter for sink, in most cases there are
three flasks. If we are talking about reverse osmosis, then flasks do not mean a membrane, post-filter, etc. since their installation does not provide a separate container. But these types of processing are taken into account in the stages of cleaning. The most obvious difference in the number of flasks is observed in the main filters, where the predominant weight per
1 flask, but there are also
models for 2 flasks or even more.
Stages of purification
The number of purification stages provided for in the filter design. At each stage, water passes through its own filter element, clearing itself of certain contaminants; in this case, the steps are arranged in order from coarser cleaning to finer. For example,
a three-stage system may look like this: the first stage is mechanical removal of impurities, the second stage is the removal of ferrous, and the third is filtration through a carbon cartridge.
The more stages of purification — the more advanced the filter is considered, the cleaner water it usually provides at the outlet. Accordingly, this moment largely depends on the purpose (see “Type”): for example, multi-stage filtration is quite rare in main models, it is practically not used at all in pre-filters, but the number of stages can reach 9 in models for sink.
Pollution clipping
The smallest size of foreign particles (in microns) that the filter can hold in total. Accordingly, the smaller this size, the higher the filtration efficiency, the less undissolved impurities remain in the filtered water. On the other hand, finer cleaning usually takes more time, which affects the speed (throughput) of the filter. It should be noted that in the case of using reverse osmosis filters, the filtration is very fine, up to 0.01 microns.
Filtration speed
The amount of water that the filter is able to pass through itself per unit of time (of course, effectively purified in the process); usually stated in liters per minute. This parameter is largely related to the type (see above): for example, in jugs, the filtration rate usually does not exceed 0.5 L per minute, while for main devices that supply entire apartments, a throughput of tens or even hundreds of liters is required.
Note that it does not always make sense to pursue a high filtration rate. After all, other things being equal, finer cleaning takes more time; accordingly, the faster the filter works, the higher the chance that the quality of such cleaning will be relatively low. And devices that purify water efficiently and quickly usually have an appropriate price. Therefore, it is worth considering the purpose of the filter and, on the basis of this, determine the balance between the filtration speed and its quality when choosing. It is also worth keeping in mind the conditions of use: for example, if you need to filter low-quality tap water for drinking, it is better to sacrifice speed in favor of efficiency.
Max. operating pressure
The highest inlet water pressure at which a filter connected to a tap or water supply can operate indefinitely (at least until the resource is exhausted, see above) without breakdowns, failures, etc. In other words, this is the ultimate strength of the filter. Therefore, this parameter has a great importance, and when choosing a filter, you must make sure that it meets the characteristics of the connection point. In this case, it is best to choose a model with a margin: although the device will not break from short-term pressure surges in excess of the working device, but this will create off-design loads and can lead to early failure.
When buying a filter for ordinary domestic use, it can be assumed that the maximum pressure in the water supply, provided for by the housing and communal services standards of most post-Soviet countries, represents 6 atm, but its actual value is usually lower. Therefore, 6 atm filters are quite suitable for the definition of a “model with a margin” for apartments with medium and especially low water pressure.
Max operating temperature
The highest inlet water temperature at which the filter is able to operate normally. Modern filters are conditionally divided into models for cold and hot water: the operating temperature in the first case does not exceed 40 °C, and in the second it can reach 95 °C. For more information on the importance of matching water temperature and filter characteristics, see "Purpose".
Types of filtration
Substances from which the filter is able to purify water. Some models may also indicate a specific degree of purification in percent for each point; the higher this indicator, the more efficiently the filter is able to cope with its functions. This list will be especially useful if you know what exactly is the most polluted water in your area — it will allow you to choose the model that is most suitable for specific conditions. In addition, in the case of softening systems (see "Type"), this data helps to determine the specific type of device — softener or iron remover.
The most common contaminants today are:
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Mechanical impurities. Particles of small size, insoluble in water and in a state of suspension. An example of such impurities is fine sand.
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Organic impurities. Impurities of various substances of organic origin — benzene, chloroethanes, chlorethylenes, etc. Many of these substances are harmful to humans. Unlike the mechanical impurities described above, "organics" refers to chemical contaminants — such substances dissolve in water, and they have to be filtered at the molecular level. This requires the use of fairly advanced filters. It is also worth mentioning that some types of organic substances — in particular, phenol, pesticides and petroleum products — stand out in separate categories, the possibility of filtering them is specifically stipulated in the specs
...of the filters. This is due to their prevalence and popularity: the term "organic impurities" is not clear to everyone, but the danger of pesticides or petroleum products is well known. See below for details on individual types of organic contaminant.
— Active chlorine. Chlorination is still used in some plumbing systems as a disinfectant. As a result, water supplied to consumers often contains dissolved chlorine, which is harmful to health. Some filters with this function, in addition to chlorine, are also able to remove hydrogen sulfide and other gases dissolved in it, which affect water quality and give it an unpleasant odour. However, these possibilities should be specified separately.
— Iron. Iron is known to many as an important trace element necessary for the functioning of the body; however, a person needs very little of it, and iron impurities in drinking water only harm the body. Note that such impurities can be present in different forms; therefore, different types of filters are required to filter them. So, one of the most famous options is colloidal iron: very small undissolved particles that give the water a characteristic “rusty” colour, as well as a metallic taste and smell. This type of impurities is effectively filtered by osmotic membranes (see "Reverse osmosis"). Also, such membranes cope well with bacterial iron — it is also in the form of insoluble microscopic particles, accumulates a specific type of bacteria that lives in water pipes. But for soluble forms (ferrous hydroxide, chloride and ferrous sulfate), it is necessary to use specialized cleaning and softening systems — iron removers; see "Type" for details. Summing up, we can say that when choosing a device with this type of filtration, it is necessary to take into account the specific form of iron that you have to deal with. At the same time, water can contain several types of such impurities at the same time, which may require complex filtration.
— Ions of heavy metals. In this case, we can also talk about salts of heavy metals: ions are formed when any salts are dissolved in water. Most heavy metals — accordingly, their compounds — are toxic to humans.
— Pesticides. Various chemicals used to combat harmful microorganisms, fungi, weeds, various agricultural pests (insects, rodents), etc. Most pesticides are toxic chemicals and are toxic to humans.
— Nitrates. Salts of nitric acid, which are a common component of mineral fertilizers (saltpeter) in particular. Most of the nitrates are converted into safe compounds during use, but excess fertilizers can end up in drinking water.
— Cadmium. A metal used in particular in anti-corrosion coatings, batteries and inorganic dyes. Poisonous both by itself and in various compounds.
— Petroleum products. Oil and various substances obtained from it (gasoline, kerosene, diesel fuel, fuel oil, etc.). It is poisonous when taken orally.
— Hardness salts. Compounds that give water increased hardness are primarily calcium and magnesium salts. Water purification from such salts is carried out by purification and softening systems based on the principle of ion exchange. For more information about such devices, see "Type", here we note that if the specs of the cleaning and softening system indicate the filtration of hardness salts, then we have a classic softener, if not — an iron remover.
This list is not complete, modern filters can specialize in other types of pollution. For example, for many main models (see "Type"), filtration from sand and clay is separately claimed. In our catalog, such moments are described in the paragraph “Additional cleaning".