How to choose a water filter

Do we often think about the question, what kind of water do we use at home for drinking or cooking? Alas, we have to admit that not everyone has yet fully understood the need for its cleaning and filtration. But this is by no means an idle question: the quality of water from autonomous sources or from a city network very often lies outside the limits of permissible sanitary norms. Simple boiling or defending can only help in part, and is unable to cope with the overwhelming number of pollution factors or even contamination.

It is gratifying that the number of supporters of a reasonable attitude towards health, one's own and the nearest environment, is constantly growing. Direct evidence of this is the growing popularity and demand for household appliances for water purification. Manufacturers of filters are constantly working on improving their products, expanding the range of products. But the variety presented in the sale can easily put in the "stupor" of the buyer, who purchases such products for the first time, and is not too well-informed on the issue of how to choose a water filter.

Where does the choice begin?

This publication will not give a detailed account of water-polluting factors, otechnologies of its purification from those or other substances, the principles of the operation of various filtering devices.

How are coarse and fine filters worked and how do they work?

It's very important to know this, but it's not worth repeating. The separate large article of our portal is devoted to the device and operation of various filters for fine and coarse water purification .

Therefore, today the focus will be mainly on consumer problems - what to choose a person to provide clean water with their housing. We will derive "beyond the brackets" and complex powerful water treatment stations, assembled from several column filters - their selection, assembly and installation should be handled only by specialists. Consider the problem in the context of purchasing a ready-made filter or filtration complex in a specialized store designed for the needs of one average family.

Any task should always begin with a clear understanding of what you want to get as a result. Buying any, in fact, things or products, a person usually already represents what features or qualities he hopes to get for his money spent. The filter for water purification is not an exception in this matter either. It is required to represent with confidence what properties it should possess.

A simplified approach such as "simply clearing water" is, of course, a complete amateurishness. Along with obvious signs of pollution( which must also be dealt with skillfully), water can contain completely invisible visually, to the smell or taste of a substance or microorganisms that pose a threat to human health.

. One should not trust either one's superficial sensations, or, especially, the advice of neighbors. Subjective opinions can lie in a wide range - from "we all drink this water all our life" to some far-fetched "horrors", which are more likely to be classified as "urban legends."And, in addition, the quality of water from neighboring nearby sources, or even in neighboring houses of urban development can vary significantly.

As a result, you can fall into one of two extremes:

• The purchase of a filter that does not have the required cleaning functions will simply be thrown into the wind by money.
• Using the obvious ignorance of the consumer, sellers in the store will try to impose an expensive filtering system, in which there is absolutely no need. In the end, it's also lost money.

The optimal solution is to pass a water sample from a source or a water pipe to a laboratory analysis. This, of course, also costs money, but such spending will be justified.

. The analysis solves many problems at once:

• You can immediately evaluate the principle suitability of an autonomous source for use in food needs.
• The results of the analysis will help to select the correct filtering system. Repeated analysis, after installing the filter, will give a clear picture of the effectiveness of its operation.
• Regular testing will help to track the dynamics of changes in the biochemical composition of water - an extremely important exercise for autonomous, especially recently equipped sources.
• The presence on the hands of the protocol of laboratory research can become a document on the basis of which there will be an opportunity to make claims to the municipal utilities.

By the way, many thoughtful people, acquiring new housing, must immediately demand the presentation of a document on the quality of drinking water.

To conduct the analysis, you need to determine the laboratory. It is not necessary to resort to the services of laboratories working with water supply organizations( they can easily go to underestimate pollution indicators), and for companies that install filtering and treatment systems( there, clearly, there can be another extreme).It is best to choose an independent organization that has the appropriate state certification.

Laboratory analyzes are divided into two types - chemical and microbiological. For autonomous, especially - surface sources, both are mandatory. For tap water, which, in theory, should already pass the decontamination stage, are often limited only to chemical breakdown, although the study on microbiology will never become superfluous.

It is more reasonable to agree in advance with the laboratory staff about the time of delivery of the collected water samples, as there are certain limitations on the shelf life( 2 ÷ 3 hours).

Water intake also requires compliance with certain rules:

For chemical analysis, it is necessary to take 1.5 liters.

• Optimal solution - a clean plastic bottle, but only from drinking still water. Use containers from under sweet drinks or beer - it is forbidden.
• The faucet opens and water is given for at least 15 minutes for a free exit.(If the source has not been used for a long time, it will take even 2 hours).
• The bottle and lid are thoroughly rinsed with the same water that will be analyzed. No detergent is used.
• Then the pressure is made minimal, so that when typing in the bottle did not create aeration - - the appearance of bubbles. Excess oxygen can greatly distort the overall picture.
• The container is filled in completely, with overflow, so that there is no air under the tightly twisted stopper.

For the biological analysis, the requirements are completely different.

• Required volume - about 0.5 liters. Tara should be absolutely sterile - if you are using, for example, a glass jar, then it and the lid to it are carefully steamed. Many laboratories practice sampling for microbiology exclusively in their sterile disposable packaging, which is issued to the customer.
• To take water, hands should be put on sterile medical gloves.

• Even before the opening of the crane, the cut of the spout is either burned, or carefully treated with medical alcohol - it is required to completely exclude the ingress of microorganisms from the side.
• The faucet opens and water is run at maximum pressure for at least 10 minutes.
• After that, sterilized container( cold) is filled to the top, and then it is tightly closed.

Usually the order execution time for qualitative laboratory water testing is about 5 ÷ 7 days. By the way, if you promise to do it literally in a day or two, this should alert you. It happens that not entirely conscientious offices conduct a superficial express test, which is then issued for in-depth research.

As a result, the customer must receive a certified protocol, which has the power of a legal document.

As a rule, this is a table in which the maximum permissible norms for water, established by SanPiN, and actually obtained indicators are indicated for clarity.

With such a document in hand and highlighting the positions that require correction, it will be possible to select filters of the corresponding direction of the action.

. Is it possible to limit yourself to carrying out independent express tests, kits for which can be purchased in stores?

The specialists on this issue have a common opinion - this analysis is not a full-fledged alternative to the laboratory one. Of course, it will show the existence of a problem, but it will not be possible to determine the exact quantitative and component pollution indices, that is, there will not be enough data for a qualitative selection of the filtering system.

And one more parameter with which to determine in advance is the required filter performance. If the article deals with devices for purifying drinking water and for cooking, it can be based on an average rate of 3 liters per day per person. Undoubtedly, the filter should not work at the limit of its capabilities, that is, it is desirable to increase this rate, say, twice.

Thus, if there are five people in the house( apartment), for example, it is not difficult to determine that it will take approximately 30 liters of purified water per day. Accordingly, the purchased device must cope with such a load.

Now we turn to the consideration of various models of household water filters.

The simplest version: the filter is the pitcher

The device of the filter-jug

For those who do not want to spend a considerable amount for the filter, do not need large amounts of purified water, or do not want to communicate with any installation or connection of the system to the water supply,advise to get a "light version" - a jug. Of course, such a solution is possible only if the quality of incoming water allows it.

jar filter. Though outwardly in shape and color, jar filters can seriously differ. The basic construction of is always the same, and does not differ much in complexity.

In fact, these are two tanks separated by a partition and communicating only through a filter cartridge.

The jar case( item 1) serves to collect purified water. It is always made of a transparent food polymer, on its walls is often placed a scale of volume - for ease of use. The capacity of the jug can vary - usually a number of models with a volume of filtered water within the limits of 1.3 ÷ 4 liters are on sale. The choice for this parameter depends on the family's need for drinking water.

The upper container( item 2) is the liner in the housing. It is also made from impact-resistant food plastic, but usually has a darker tone( the color may be different - depending on the design idea).This compartment is designed to receive water to be filtered, and its capacity, as a rule, is about half the useful volume of the jug.

In the lower part of the liner, where it forms a kind of funnel, there is a nest in which the filter cartridge is firmly inserted and fixed( key 3).The purpose, that is, the functionality of the cartridge, can be different - this is selected based on the existing "clinical picture" of the water state.

It is important to know that the lock or screw connection of a cartridge with an upper capacity can vary significantly from one manufacturer to another. Apparently, this is a method of stimulating to purchase only branded components.

In the upper part of the housing there is a spout - for the convenience of directional draining of filtered water( item 4).The design is such that even with a strong tilt of the jug near the water from the upper and lower compartments, it is not possible to randomly mix.

The water for filtration is set with the cover folded back( key 5), which can be equipped with a convenient lock( key 6), or through the hatch, which also necessarily has its cover to prevent accidental ingress of dust or debris inside.

The jar filter always has a comfortable handle( key 7).On the top or on the handle can be placed a "reminder" - a mechanical calendar that will tell the owner about the timing of changing the filter cartridge. There are expensive models, which have an electronic indication. Moreover, when selling some brand models, customers are registered, who will subsequently receive Internet or SMS messages about the need to replace.

The scheme of operation is obvious - water is poured into the upper tank independently, without any impact, only due to gravity, passes through the filling of the cartridge, receives the required cleaning and accumulates in the jar. As consumption of water for drinking or kitchen needs, new portions are poured into the receiving capacity.

Applied cartridges

The cartridge is the most important element of such a filter, so its focus should be on its selection.

The shape of the cartridge and its lock part can be different, and the interchangeability of speech is almost not, unless, of course, it is not specified by the manufacturer.

But the cartridges for one filter model can have a different purpose:

• Selling elements for water of standard quality are sold - they help to cope with possible unpleasant odors, normalizetaste, remove heavy metal ions, chlorine impurities, organic compounds, and the like. The usual sorption material for them is granular activated carbon.
• There are cartridges with a pronounced softening effect - they additionally introduce a certain amount of ion-exchange resins.
• You can choose a cartridge for a source with a high content of iron - they use a reagentless technology of deironing and filtration.
• For sources, water from which does not pass the decontamination stage, there are special elements with bactericidal effect.
• Cassettes are produced, filling of which presupposes a health-improving fluoridating effect on water.

Most companies use silver in some form of filler in cartridges - this prevents the development of bacterial colonies inside them. And besides, each of the manufacturers tries to surprise the consumer with their own original developments.

Usually at the inlet and outlet of their cartridge there is a mesh or membrane, performing the function of mechanical filtration. In addition, usually in the replaceable elements has a special throttle device that equalizes the speed of water passing through the filler, regardless of the level of filling the top of the jug.

Advantages and disadvantages. Parameters of selection of filter-jugs.

The positive qualities of the filter-jugs can be said as follows:

• Their operation is the simplest, from which any person can cope.
• No installation operations, except for connecting the cartridge, simply no. Ideal for work, hostel or for rented housing.
• A jug can be easily taken with you as needed, for example, for a trip to rest.
• Low cost, affordable to any family.

There are also significant drawbacks of this filtration:

• Cleaning is performed only in certain portions. For example, to collect a five-liter kettle, you will have to make two filter fillings.
• Cleaning speed is low, rarely reaches a threshold of 400 ml / minute, and more often - even much less.
• Replacement of the cartridge is required( approximately once a month and a half).With a large consumption period may be even less.
• Sufficiently high operating costs in terms of the amount of filtered water, if viewed from a perspective. So, after a year and a half or two years, the total costs can be equalized, and even exceed the costs for a really powerful and qualitative multistage filtration installation.

When selecting a jug filter, care must be taken, as the market is riddled with cheap counterfeits.

Do not buy them in random places - there are specialized shops for this. It is best to choose models of famous brands.

Inspect carefully and, literally, sniff the body. No smells should the polymer emit. The food plastic must have the appropriate pictographic markings shown in the figure.

was used to make the jug. Immediately it is necessary to evaluate the possibility of purchasing original replacement cartridges of the required functionality, in accordance with the quality of the water source, and their price availability.

It is necessary to take a reasonable approach to the choice of the pitcher by volume. Remember - such a filter is not a "decanter" at all, but serves only to purify water. The capacity of the vessel must correspond to real needs with a small margin. Do not store filtered water for more than a day. So, you'll have to simply drain the surplus, wasting the resource of the replaceable cartridge in vain.

Usually for a single person or for a couple a pitcher is sufficient for a liter and a half. About buying a filter of maximum capacity, about 4 liters, it's fashionable to think only if it is used in a large family.

The cartridges to be purchased must be in the original sealed packaging. It is mandatory to check their expiration date.

The convenience of the pitcher and its external design are certainly important criteria, they should still be evaluated last.

To complete the section on pitcher filters - a short review of popular models from well-known manufacturers and some cartridges for them.

Model	Illustration	Capacity( jug / hopper) or cartridge life( liters)	Estimated cost
Manufacturer - "Barrier"
Barrier-style jug, compact arrangement, mechanical resource indicator		2.5 / 1.0	490 rub.
Pitcher "Barrier Grand NEO Ruby", volume scale, mechanical resource indicator		3.7 / 2.0	550 руб.
Cartridge "Barrier - 7 iron" for standard and cleaning and deironing of water		350	250 rub.
Cartridge "Barter-Ultra" for filtration and bactericidal treatment of water		200	400 rub.
Manufacturer - Aquaphor
Aquafor Line jug of classic design, compact size		3.2 / 1.4	350 rub.
Jug "Aquafor Prestige", mechanical indicator		3.0 / 1.35	540 rub.
Cartridge B100-15, universal action		170	155 руб.
Cartridge B100-6, softening		300	320 rub.
Manufacturer - "Geyser"
Pitcher "Geiser Matisse-Chrom", graphite or deep blue, plastic of increased heat resistance		4.0 / 1.5	840 rub
Pitcher "Geyser Dolphin" - stylish model with a choice of 5 shades		3.0 / 1.4	380 rubles.
Cartridge "Geyser 502", universal, with softening effect		300	210 руб.
Cartridge "Geyser 301", universal type		300	170 rub.
Manufacturer - "Vrita"
Pitcher "Elemaris XL", with electronic cartridge lifetime indicator		3.5 / 1.5	1450 rub.
Pitcher «Marella XL», electronic indication		2.2 / 1.2	790 rub.
«Brita Classic» - universal cartridge. Approaches to some models of jugs "Aquaphor"		150	290
"Brita Maxtra" - a cartridge with four steps of water treatment		150	360 rub.

Video: overview of the filter-jugs of the brand "Barrier"

Filters in the form of a nozzle on the crane

Another type of filter, which can be attributed to the simplest water treatment systems.

As you can understand from the name, these devices are simply put on the nozzle spout of the mixer. The filtration of water is a continuous process, due to the pressure in the pipes. This makes it possible to use carefully packed sorbent backfill in these filters, in contrast to the jar cartridges, that is, to improve the quality of water purification.

The design of the nozzle filters can be different. The simplest ones are a cylinder with a filtering fill, which is put directly on the spout. The device of one of the models is shown in the diagram:

This is a cylindrical body made of transparent or opaque food plastic( item 1).The design can be non-separable, disposable, or be equipped with a removable cover( item 2), which allows to replace the filtering fill or the installation of the cartridge.

A device for tight fitting the filter on the mixer spout is mandatory. In this case, it is a rubber cuff( item 3), but there may be a threaded connection or adapters for the saddle in which the divider-aerator is usually mounted on the mixer. From the bottom of the filter, at the outlet of the water, there may be a dissector( item 4), according to the principle of the shower.

A sorbent backfill is placed inside the cylinder or cartridge. The example shows a mixture of activated carbon( item 5) and mineral crumb( pos.6), which is necessary for reagentless water purification from iron and other dissolved inclusions.

The filling is top and bottom protected by filtering membranes. The upper one( item 7) cleans water of insoluble suspensions, the lower one( item 8), besides, prevents small particles of sorbent and products of iron oxidation from entering the purified water.

As already mentioned, the design can also be non-separable, that is, the filter itself is a cartridge that is recycled as the resource is developed.

crane. The disadvantage of this circuit is the need to attach the filter to the mixer tap when there is a need for filtered water. This problem is eliminated in models equipped with a stream switching device - a divertor.

In this case, the main filter cylinder with the cartridge installed is installed with offset to the side. Switching the tap of the divertor allows either to open a direct flow of unfiltered water, or to redirect it for cleaning - there is a separate hole for the exit.

divertor The main advantage of such filter-attachments is small dimensions. The commercially available adapters make it possible to install such devices on virtually any mixer, either with smooth coils or with a threaded coupler.

The life of cartridges is usually much higher than that of filter jugs, due to the density of the sorption backfill.

However, the performance of such filters or cartridges to them is low, usually does not exceed 200-300 ml / min. That is, to simply fill the kettle, you will have to stand quite a while near the sink. Many non-assembled models do not differ in the variety of functional possibilities for water purification - the filtration in them is reduced to the average minimum.

They are not very convenient for operation. If the filter is removable, then any worries of the filtered water require the installation of the device and its subsequent removal. In the case when the filter is executed in accordance with the scheme with the divertor and is constantly on the mixer spout, it clutters the working space in the sink, which can cause certain inconveniences, for example, when washing large dishes.

It is difficult enough to adapt correctly to choose the head for quality filtration - at too high water speed, the quality of its cleaning decreases drastically. In addition, there is a very high probability of accidental start-up through the filter element of hot water, which leads to a rapid exhaustion of the cartridge with its resource, the need for replacement, or certain regeneration operations.

Model	Short description	Illustration	Average price
"Aquaphor B300"	One of the simplest filters in the device - nozzles. Purification of water from chlorine, mechanical impurities. The adapter is included. Resource - up to 1000 liters. The filtration rate is 300 ml / min.		from 130 rubles.
Aquaphor Topaz	Model with a diverter switch. Cleaning - sorption single-stage. Replaceable filter module( cartridge) with a resource of 750 liters. The filtration rate is 300 ml / min. Dimensions 132 × 95 × 58 mm. Mechanical calendar-memo.		390 rub.
Barrier Selekta	Filter nozzle with a divertor in a stainless steel housing. Filter element with conventional sorption and ion exchange resin for water softening and deironing. Cartridge life - 500 liters or 3 months of operation. Adapter kit for connection to any mixer		620 rub.
«DeFort DWF-500»	Filter nozzle with a divertor. The increased life of the replaceable module and the filtration rate is 5000 liters and up to 20 l / min.respectively. Dimensions 158 × 136 × 80 mm, weight in unfilled water state - 430 g.		540 rub.

Filters-nozzles of desktop type

The scheme of connection of similar filters, in principle, differs little from the above mentioned nozzles on the mixer. The main difference is that the housing itself with the filter module is located on the kitchen countertop in the immediate vicinity of the sink, and a flexible tube connects it from the mixer spout.

By increasing the volume of the filter module, the productivity of the device, the quality of water purification and the life of the sorption material are significantly increased.

Typically, these filters are executed in the form of a vertically standing cylinder. Schematic diagram of any of them in general terms corresponds to the following scheme:

In the cylindrical casing( item 1) there is a replaceable filter module( item 2).Its considerable volume allows, if necessary, several types of sorbent backfill to be used for thorough multilateral water treatment( item 3).There are models without plug-in modules - as the resource is spent in them, replacement or regeneration of the backfill is performed.

The filter is equipped with its own spout( item 4) for easy collection of purified water in the dishes. Often, a powerful annular magnet( item 5) is installed at the output of the module for additional "sanitation" of water. The top cover is closed with a cover( key 6).

A connecting sleeve( key 7) is provided at the bottom of the replacement cartridge or work cylinder to connect the flexible tube( key 8) that goes to the mixer outlet. The connection to the mixer itself can be carried out using an adapter coupling( key 9) or via a divertor( key 10).

Diverters are usually purchased separately - they are always presented in the shops dealing with the implementation of filters - it is possible to select a particular type of mixer.

. The advantages of such desktop filter nozzles are an increased resource and productivity. The device does not clutter the space directly above the sink.

However, there are also a lot of shortcomings. The design is large enough and will occupy a lot of useful space near the sink, to which it is "tied."When using a coupling coupling, the inconvenience is the same as for a compact nozzle - the need to connect and disconnect with each set of filtered water. If the connection with the divertor is used, the tube extending from it may interfere with it.

Recruitment of water of such a filter requires care - careless inclusion will lead to spillage of liquid on the surface of the table. The probability of accidental start-up to the hot water filter is retained to the full.

Model	Short description	Illustration	Average price
"Aquaphor Modern"	Body spindle-shaped, cast to the side of the spout. Dimensions 273 × 117 mm. The filtration rate is up to 1.2 l / min. Resource replacement cartridge B200 - up to 4000 liters. Mechanical calendar is a reminder.		770 rub.
"Barrier Optima"	Original design, microprocessor control of the residual life of the filter module. Turning spout. Cartridge life - up to 1500 liters. The filtration rate is up to 1 l / min.		1200 rub.
"Spring-3M"	Model for placement on the wall. Dimensions 315 × 120 mm. The weight in the unfilled water state is 1 kg. Resource of the replacement module - 3600 liters. Filtration rate - up to 2 l / min.		790 rub.
"Geyser 1 UZ EURO"	Modern model with a wide selection of filter modules of various functions with the possibility of regeneration. Resource module - up to 25 000 liters, including without regeneration - up to 7 000 liters. The filtration rate is up to 1.5 l / min.		1500 rub.

Filter systems with a sink

The universal filtration and fine water treatment plants, which are usually located under the kitchen sink, are gaining popularity among users.

. Structurally, such systems are usually a series of cartridge filters, each with its own cartridge of a certain type of action.(The construction of such filters is described in detail in the article, the link to which is placed above).Water on the way from the water pipe to the point of analysis consistently passes all the modules, which provides a comprehensive cleaning of the highest class.

All filters are generally assembled on one console with a system of channels or pipes for transferring water from one module to another. There are models with body design, in which the entire system is closed with a casing.

Enclosure The arrangement of the filter flasks is most often linear. In some multistage systems it is possible to arrange in two rows or in two tiers, with vertical and horizontal arrangement of modules.

Number of modules, that is, cleaning stages: from minimum - one, up to four, and sometimes even five. This causes the highest "flexibility" of the system - the mounting dimensions of replacement cartridges, as a rule, are the same for a single manufacturer, which allows you to accurately select the general characteristics of the entire complex, depending on the results of laboratory water testing.

Such complexes are very convenient to operate. When they are installed, the water supply is immediately connected to the water supply, and a separate tap connected to the last stage of filtration is installed on the sink. At any time, you can substitute the container, open the tap and collect the required amount of purified water. Moreover, the diameter of the commutation pipes, connecting channels and the parameters of the external tap provide an optimal head for quality filtration - there is no risk of exceeding it. In addition, the probability of accidentally letting hot water into the filter modules is completely eliminated.

The disadvantages of such complexes can be considered only a certain complexity of the primary installation, although for the owner, who is familiar with the basic plumbing techniques, there should not be any special problems. And the relatively high cost of such complexes can hardly be attributed to drawbacks: high quality of cleaning costs such costs, and a considerable resource of plug-in modules ensures a quick payoff of the filter unit.

The choice of such filtering systems has its own peculiarities.

• As it is assumed that the installation is hidden under the sink, external design issues, as a rule, are not among the primary ones. Much more important is the correspondence of the dimensions of the complex to the real dimensions of the space allocated for its installation.
• As the system assumes, more often than not, a multistage cleaning, it is necessary to be guided not by persuasions of the seller-adviser, and on available results of laboratory research. It is important to prioritize the priorities in order to choose the correct modular content of the kit.
• Some complexes have an expanded functionality - after the first stage of mechanical cleaning, a branch goes to a conventional mixer or dishwasher, heater, etc.
• Evaluating the performance of the complex as a whole, one should be guided by the indications of the "slow" cartridge itself. Usually at the outlet from the tap is provided an expenditure of about 1.5 ÷ 2 liters per minute - a completely acceptable characteristic.
• Filter modules can also vary in the amount of their resource. For this owner will have to monitor yourself, as, perhaps, the replacement of cartridges sometimes will need to be performed not at once, but "stepwise".Some modules are amenable to periodic regeneration.

Of course, you should check the completeness of the delivery. Typically, the system is supplied with everything I need for its complete installation - a suspended or floor console, flasks, a set of cartridges( it can often be chosen at your discretion), a tee for tapping into a water pipe with a pressure regulator, connecting pipes, a tap for a sink,"Zapkovki" flasks with cartridges. Sometimes the kit includes additional accessories - all this is indicated in the product's passport.

Model	Short description	Illustration	Average price
Aquaphor Solo Crystal	The simplest single-stage sorption cleaning system. Dimensions 260 × 340 × 90 mm. Productivity up to 2.5 l / min.		2500 rub.
«Aquaphor В510-08»	Replacement module for deep water purification. Resource - 4000 liters or 6 months.operation		350 - 400 rub.
Atoll A-211Eg( D-21s STD)	Two-stage system with mechanical and sorption filtration and hard water softening. Dimensions 355 × 365 × 145. Productivity - up to 3.8 l / min.		7300 rub.
Atoll A-211E + Atoll A-211E g	Additional set of cartridges designed for 2 years of operation with a change every 6 months		4000 rub
"Barrier Expert Complex"	Three-stage purification system - mechanical filtration, sorption cleaning, softening and deferrizationwater. Dimensions 368 × 267 × 95 mm. Productivity - up to 2 l / min.		3700 rub.
«Expert Complex»	Complete set of cartridges. Resource 10000 liters or 1 year of operation		1400 rub.
Aquaphor Crystal ECO N	System with four cleaning stages, including disinfection, softening, iron removal, mineralization and water conditioning. Dimensions 377 × 342 × 92 mm. Productivity - up to 2.5 l / min.		4800 rub.
Aquaphor K3, KN, K7 and K7V	A set of four replaceable cartridges with an increased life - 8000 liters or 18 months.		2200 rub

Video: Advantages of the "Aquaphor-Trio" water filter

Reverse Osmosis filters

The highest values ​​of water purification from any inclusions, chemical or bacteriological contamination, show filtration plants in which, in addition to conventional cleaning, a step is applied,working on the principle of reverse osmosis.

For a start - what is reverse osmosis?

If the vessel is separated by a membrane with microscopic pores, and then liquid is poured into these sections with different concentrations of impurities, the system will not learn the equilibrium. The liquid from the compartment with a lower concentration will spontaneously tend to the opposite, in order to equalize the overall concentration. This phenomenon is called direct osmosis.

But if an external action is applied to the volume of a more concentrated liquid - to increase its pressure, then the flow through the membrane will begin to take place in the opposite direction. And only on the size of the cells of the membrane will depend that it will go to the next department.

This is exactly how reverse osmosis filtering systems work.

Water enters the filter module under pressure( arrow No. 1).The module itself is divided into two parts by a membrane( a red arrow), the dimensions of the microperforations of which are only about 0.3 nm, so that they let the molecules of water pass. Thus, small water molecules penetrate into the second half, from where the filtered water flows to the points of accumulation or consumption( arrow No. 3).All larger molecules, not to mention mechanical suspensions, bacteria and even most viruses are reliably retained on the membrane, and are discharged together with the concentrated solution into the drainage( arrow No. 2).A common phenomenon is the proportion ⅓ of the total volume of purified water and ⅔ of the discharged concentrate.

In principle, such a scheme is able to independently clean water of any degree of contamination. However, in order not to "overload" the membrane, and so that its pores do not overgrow, several stages of preliminary filtration are envisaged. In addition, some molecules( for example, free chlorine, which is constantly present in tap water) are smaller in size than water ones, and they must be disposed of in advance. Therefore, preliminary filtration involves not only mechanical, but also sorption purification.

The output is water, which in its characteristics is close to distilled. From the point of view of cleanliness - this is excellent, but from the standpoint of consumer qualities - not very much. Such demineralized water is devoid of even the slightest taste and smell, it is not suitable for drinking, and dishes made from it will not be the most delicious. Moreover, many physicians agree that water of such a degree of purification may even be harmful to the human body.

In order to eliminate this drawback, additional modules are usually installed in the filtering systems of domestic use, usually after the reverse osmosis. Usually it is a mineralizer, which enriches water with the necessary mineral salts for humans. Can also put a carbon post-filter, a biothermal module that normalizes the bio-composition of water. And if special sterilization is required, then at the end of the cycle can stand and ultraviolet lamp.

The cost of such installations is high enough, therefore it is necessary to immediately determine how much there is in it. In addition, the selection takes into account a number of important criteria.

• For the reverse osmosis process, a minimum pressure of about 2.8 bar is required. Not always water supply systems meet these parameters. Hence, it will be necessary either to install a pump that raises the pressure in the system, or it will be necessary to purchase a complex equipped with a built-in pump. That is, there will be a need to organize more and power.
• Very much "how many" is the issue of the performance of the filter unit. Here it is important to find a "golden mean", so that the need for clean water is ensured, and unnecessary surplus is not created. Do not forget that in order to get a liter of purified water about two liters you have to drain into the sewer. That eats to use such water for economic purposes will be extremely unreasonable.

Even the smallest plants can produce up to 100 liters per day - this is more than enough for any family. So chasing the high rates - it is unlikely, especially since this affects the cost of the installation itself.

• It should be determined which installation will be more convenient to use - cumulative or flowing. In flow-through systems, filtration takes place only with an open water tap - more productive membranes are installed. In another variant, the system has its own storage tank - the filtration process is only necessary if the total volume of accumulated treated water is reduced to a certain level. Very convenient - the owners always have a supply of clean water. The disadvantage is the considerable dimensions of the installation in the collection. But the price of such complexes is also much lower.

The most expensive module, of course, is reverse osmosis, but its life is large enough - the membrane usually lasts up to three years of operation. The remaining replacement cartridges are changed more often, as the resources are built into them. Usually the prefilters serve up to six months, and the carbon cartridge of the post-cleaning cartridge is up to a year. After its depletion, water can "signal" a bitter taste.

The cost of such installations really looks frightening. However, if you sit down with a pencil and a calculator in your hands and bring the entire amount of costs for several years to the cost of one liter of filtered water, you can be sure that it will still be cheaper by almost an order of magnitude than buying bottled purified water, which, incidentally,are also obtained using reverse osmosis technology.

Model	Short description	Illustration	Average price
Aquaphor OSMO 100 PN sp.6	Three-stage pre-treatment, mineralizer and post-filter. Storage tank 10 liters. Built-in pump. Productivity 15,6 l / hour.		14000 rub.
«Geyser Prestige PM»	Six stages of preliminary and post.cleaning. Storage tank 12 liters. Productivity - 12 l / hour. Two crane positions - for clean and mineralized water.		14100 rub.
"Barrier Pro Osmo 100 boost"	Five-step cleaning, built-in pump. Storage tank for 8 liters. High performance - up to 20 l / h.		11000 rub.
"Atoll A-560E SailBoat"	Original monoblock design, simplifying the installation of the system in the space under the sink. Dimensions 410 × 420 × 240 mm. 5 cleaning steps. Built-in 8 liter diaphragm tank. Capacity - up to 6 l / h.		20000 rub.

Video: household filtration unit with reverse osmosis system "Aquafor-Morion"

Concluding the publication, the author expresses the hope that the information obtained by the reader will help in choosing the best household filter for specific operating conditions.