How to choose a water filter for drinking water
According to physicians, it is not recommended to drink tap water in most cities in America today. However, we cannot say that this problem is unique to the United States - in many countries not only in Asia and Africa, but also in Europe, the situation is the same. And there are only two ways out for a health-conscious person:
- Put a dispenser and order the delivery of bottled water
- Install filters on the water supply.
Before you go to the store to buy a filter, you should deal with the main question - what is contaminated water and how badly. Different types and degrees of contamination require different types of filtration. The best thing to do here is to order a water analysis from a lab. You'll get a list that clearly indicates how many times the maximum allowable concentrations (MAC) are exceeded in your water.
It is also advisable to understand how much clean water you need. If the water in your tap is clean enough and you need a little drinking water, you can get by with a pitcher-filter. If your family is more than two people or contamination is several times higher than the MAC for some indicators, you will have to put a water filters.
Characteristics of water filters
Type.
Mainline technical filters are plugged directly into the water pipe and are usually used for initial water purification.
Main-line filters by design can be divided into two types: mechanical filters with backwashing and housing filters under the standard cartridges of different sizes. Which one to put where?
Backwash filter is installed for coarse water purification from large mechanical impurities - sand, rust and other inclusions with a size of 100 microns. Such a filter does not require replacing the cartridges - if the filter element is heavily contaminated, it can be washed.
Rinsing is done by opening the tap on the bottom of the filter housing - the dirt particles accumulated on the filter screen are flushed down the drain. To be able to monitor the degree of contamination of the filter, its body is sometimes made transparent. For the same purpose, the filter is often equipped with a manometer - if the inlet to the apartment (or house) has another manometer, the pressure drop can track the contamination of the filter.
Such a filter will not be able to clean water from chemical and microbiological contaminants, and even mechanical particles smaller than 50 microns will freely pass through it. But if you have another stage of mechanical purification, this filter can not be considered unnecessary - it will trap large particles and prolong the life of the cartridge in the next filter.
Shell filters are more versatile - depending on the cartridge installed, they can remove mechanical inclusions as small as 1 micron (mechanical cartridges), hardness salts, iron (ion-exchange) and microbiology (carbon, silver, etc.) from water. The filter size is chosen according to the planned flow rate and water pollution.
Drinking water flow filters are designed for drinking water treatment and are usually installed in the kitchen. All flow-through drinking water filters can be divided into two types:
- using standard cartridges (K87X, SL10);
- using the manufacturer's original cartridges.
The most versatile and economical option - multistage filters under the cartridges SL10 - cartridges of this type are the most common, have a low price and a sufficient resource. You can easily pick up the necessary cartridges (by analysis of water) and install them in the filter with the appropriate number of stages. The disadvantage of such a filter can be called only some complexity (and "dirtiness") of changing the cartridges.
Filters based on the K87X cartridges are compact, have a nice look, and replacing their cartridges would hardly puzzle even a child. But the life of such cartridges is much less, their performance is also low, but the price is even higher than SL10.
Filters based on the original cartridges may be more attractive in price or size, but you should keep in mind that there may be problems with replacing a non-standard cartridge. Not to mention picking a different type of cartridge than the one in the filter (e.g., ion exchange instead of carbon) - the cartridges you need may simply not be available from the manufacturer.
Reverse osmosis system
Reverse osmosis system is the most "advanced" kind of flow-through drinking filter. It differs from conventional multistage filters by the presence of a special filtering stage - the reverse osmosis membrane. The pores of such a membrane are about 0.1 nanometer in size, which allows it to pass only pure water and some gases, trapping all molecules of larger size.
Such filters provide the maximum degree of water purification, but they also have some disadvantages:
- the filtration rate of reverse osmosis filters is very low, without a storage tank it makes no sense to use them;
- reverse-osmosis filtration requires a considerable amount of water to go down the drain;
- For operation of such a filter, a water pressure of at least 3-4 bars is required. If the inlet pressure is below 3 bar, you should use a pressure booster pump.
Faucet nozzle - the most budget, easy to install and operate type of flow filter. However, it should be understood that the life of such a filter is many times less than that of full-size filters based on 10SL cartridges.
Therefore, it makes sense to use such filters only on fairly clean water and at a low flow rate, otherwise they will clog rather quickly. Given the fact that most nozzle filters are disposable, seemingly low price of such a filter can rather quickly lead to unexpectedly high costs.
When choosing a filter, it is advisable to know the pressure in the water system.
If the minimum pressure of the filter is more than the pressure in your network, the performance of the filter will be low (or zero). Pressure in the network greater than the maximum pressure of the filter can lead to leaky connections of the filter or even to its failure. For municipal water mains, the standard pressure is set at 4 bar. However, in some areas the pressure can be higher - up to 5 bar, and because of water hammer briefly rise to 6-7 bar.
Therefore, for a city apartment (especially - new and located on the lower floors) is better to take a model with a reserve of the maximum pressure. In private homes, the pressure is usually set at 2-3 bar - some multi-stage filters that might not be enough.
High-pressure pump
High-pressure pump can help if the water pressure in the pipeline below the required. The pump will create the required pressure in front of the filter and provide the rated capacity at any parameters of the water supply.
The storage tank is used with filters with a small capacity. For example, you can quickly fill a large pot that would otherwise take a long time to fill in a thin stream.
You should pay attention to the maximum water temperature when selecting a hot water filter - especially if plastic is used as the housing material. When heated, it decreases its performance characteristics, hot water can damage the plastic housing, even if its pressure will be within the permissible limits.
The life of the filter elements (cartridges) indicates how much water the filter is able to purify before the cartridges are replaced. If the cartridges are not replaced at the end of their life, the quality of filtration will be reduced. Total life for disposable filters is equal to the life of the filter element, while for filters with interchangeable cartridges it indicates the reliability and durability of the design.
Filtration rate determines the rate of water flow through the filter, at which the purity of the filtered water will be provided. In some cases (e.g. for reverse osmosis filters) the filtration rate does not depend on the flow rate, and it is almost impossible to exceed it. But with backwash filters the situation is different: if the current flow rate exceeds the passport value of the filtration rate, the quality of water at the outlet of the filter will be worse. Therefore, flow filters should be selected according to the planned flow rate on the filtered pipe. For washing hands and dishes a flow rate of 4-6 l / min, for showering - 10-12 l / min.
The number of filters (the number of purification stages) should be chosen according to the need - according to the water analysis. For example, if the analysis revealed excess of iron and microbiology, while the water itself contains almost no mechanical impurities, it will be sufficient to have three cartridges - a mechanical purification of 5-10 microns, ion exchange and carbon. If the water is dirty (contains a lot of mechanical particles), instead of one cartridge of mechanical treatment will need to install 2-3 stages with different porosity.
Water filter. Cartridges.
Filters, depending on the cartridges installed in them, can perform various functions:
- mechanical purification;
- reverse osmosis;
- sorption - absorption of organic compounds, toxic substances, bacteria and other contaminants depending on the sorbent used;
- ion exchange - removal of hardness salts and dissolved iron from water;
- odour elimination - absorption of aromatic molecules;
- mineralization - saturation of water with microelements.
The type of connection to the pipeline largely determines the ease of installation and maintenance of the filter. Threaded connection is the most reliable and durable, but some plumbing skills will be required to install a filter with this connection.
The size of the threaded connection must match the size of the threads on the water pipe to which the filter is connected. John guest type quick disconnect fittings are very easy to connect, but the problem is that there are no mating fittings of this type on water pipes.
Many manufacturers complete flow filters with a tee ball valve with a threaded-through connection on one side and a john guest fitting on the other. If such a valve is not included, you will have to buy it separately.
The size of the threaded connection must match the size of the threads on the water pipe to which the filter is connected. John guest type quick disconnect fittings are very easy to connect, but the problem is that there are no mating fittings of this type on water pipes.
Many manufacturers complete water filters with a tee ball valve with a threaded-through connection on one side and a john guest fitting on the other. If such a valve is not included, you will have to buy it separately.