How to choose and install water purification filters from a well

Recommendation points

• Contamination types and filter selection
• Selection of filters for cleaning from mechanical impurities
• Selection of filters for cleaning from chemical impurities
• Filters for cleaning bacteriological impurities
• Installation site and installation recommendations
• Accommodation guidelines
• Installation recommendations

The water from the well is not suitable for drinking and the operation of plumbing equipment without preliminary treatment. About what filters are, where and how they need to be installed to provide a country house with clean water with autonomous water supply, we will tell in this article.

Water purification from a well is required in almost all cases. The decision on the number and types of filters is made based on the results of water analysis for the content of various substances and microorganisms, as well as in accordance with the capacity of the pumping station.

Contamination types and filter selection

Water for analysis must be handed over not only when the well is put into operation. Indicators may change, which is associated with a change in the characteristics of the water flow and with contamination of the filtering equipment.

Well water pollution happens:

• mechanical (sand, clay, silt);
• chemical (iron, manganese, potassium, magnesium, hydrogen sulfide);
• biological (iron bacteria and pathogenic bacteria).

For example, the analysis showed an excess of indicators for turbidity, hardness and total iron. This means that a coarse filter, an iron remover, a softener and a fine filter will need to be included in the water treatment system.

Selection of filters for cleaning from mechanical impurities

Mechanical impurities present in high concentration, as well as coarse suspended solids (sand), are separated directly in the well. For this, coarse filters are installed, the design of which includes a pipe with a perforated surface in the form of a mesh, a wire mesh, round or oblong holes. There can be more than one such filtering layer.

When choosing a filter, it is advisable to give preference to those made of stainless steel grades. Galvanized elements have a significantly shorter resource, the durability of plastic ones is even lower. However, if there is hydrogen sulfide and free oxygen in the water, it is advisable to choose the filter from plastic that is neutral to their effect (in agreement with the SES). The choice of filter also depends on the soil surrounding the well and the water horizon. In solid limestones there is little suspended matter, normal acidity, practically no biological pollution – this is one of the cleanest sources of natural water. The well “on the sand” must be equipped with a filter, otherwise the rest of the water supply system will instantly clog.

Coarse wire filters for wells

Slotted coarse filters

The height of the filter in the well is calculated using the formulas based on the thickness of the aquifer and the fractional composition of the suspension. Roughly, the length for medium-grained and coarse sand is from one to two meters, fine-grained sand is captured by a filter up to 4 m in length, and dusty sediments up to 6 m (if the thickness of the aquifer allows). The diameter of the pipes must correspond to the well, located in it so that a free flow of water is provided, and is usually 70–150 mm.

Selection of filters for cleaning from chemical impurities

To purify water from chemical contamination, more sophisticated devices are used. As a rule, it is required to install several filters and softeners in series so that the water quality meets the standards for drinking water and does not harm plumbing, boiler, pipes.

Devices can be divided into groups:

• to remove dissolved iron (ferrous);
• to remove iron in the form of solid particles (trivalent);
• to remove calcium and magnesium.

Various schemes and devices are used for deironing from ferrous and trivalent iron..

Oxygen is needed to convert dissolved iron into a solid phase. Therefore, the first stage of deironing can be a pressure or non-pressure aerator. The pressure head includes a compressor in the circuit that supplies air to the tank with water, due to which it is violently mixed and in contact with air. Free-flow works thanks to the installation of spray nozzles that increase the area of ​​contact between water and air. The first way is more productive. Sometimes, to enhance the effect, the aeration column is a complex of methods: with nozzles and a compressor.

Aerator for oxidation of ferrous iron: 1 – inlet pipe from the well; 2 – compressor and air duct with aerating stone at the end; 3 – outlet pipe to the fine filter and consumer; 4 – precipitate of oxidized ferric iron

An illustrative example of an aerator used in an industrial wastewater treatment plant

Further, oxidized iron salts that have passed into the solid phase must be captured in reagent or reagent-free filters. Both of these filters contain backfill to keep the hard ferrite salts from entering the water supply. Their difference lies in the fact that the reagents include the supply of a strong oxidant (potassium permanganate, chlorine), which accelerates the oxidation of ferrous iron to ferric. Reagent-free filters necessarily work in tandem with an aerator, and reagent filters can be the only deferrization stage when the ferrite content is below 5 mg / l.

Manganese and hydrogen sulfide are captured in the same way as iron, simultaneously with it in the same apparatus.

Removal of calcium and magnesium is required to soften the water. The best filter for this is an ion-exchange polymer resin, which is located in the tank and replaces harmful ions with an equivalent amount of harmless ions (for example, sodium). Depending on the acidity of the water, cationic or anionic filters are used. Also, resins are distinguished by structure: porous or gel.

When the capacity of the resin is completely depleted (there are no more ions for harmless exchange), it is replaced or regenerated with salt.

Many impurities, including dissolved ones, can be removed from the water using a reverse osmosis filter. The principle of operation of such a filter consists in pushing exclusively water molecules through the membrane under pressure. All other inclusions, including chemicals and organic compounds, as well as radionuclides with larger molecules, cannot penetrate the membrane. The degree of purification is 90–99%. However, almost 60% of water is spent only to clean the membrane of impurities and does not reach the consumer, draining into the sewer.

Household reverse osmosis filter

High performance reverse osmosis purification system

Reverse osmosis is equipped with several successively installed pre-filters of a finer purification, which prevent the main filter from clogging up too much. To clean the membrane, the filter design provides for the separation of the water flow, and the second flow is designed to flush the ferrite sediment from the membrane into the sewer.

Filters for cleaning bacteriological impurities

Iron bacteria can significantly contaminate the source, so much so that further filtration cannot be effective. When the aquifer is damaged by these microorganisms, shock chlorination of the source is required. This procedure requires accurate calculation and laboratory control of analyzes, therefore it is better to have it performed by a specialized company. When chlorinating a source, it is advisable to add a filter with a carbon cartridge to the water treatment system to neutralize chlorine.

Anaerobic microorganisms and iron bacteria are often found in the water from the well. If the well is shallow, there is a risk of detecting pathogenic aerobic bacteria

Pathogenic bacteria that can get into shallow water horizons are safely destroyed with an ultraviolet disinfectant. In the central water supply, this function is performed by chlorination..

The UV installation is usually built in after the main filters and is supplied with a sensor when its intensity decreases. The required design dose of radiation, indicated in the characteristics of the UV unit, is selected depending on the degree of damage to water by microbiological organisms. The emitter can be installed vertically or horizontally.

Installation site and installation recommendations

Reliable operation of the system depends, among other things, on the correctly selected scheme and installation location, as well as on the correct installation.

Accommodation guidelines

To protect the water supply system from water hammer, and the pumps from frequent operation, as well as to maintain a stable pressure, a hydraulic accumulator is built into the water supply system. The signal to turn on / off the pumping station is supplied from the pressure switch.

General diagram of the well water filtration system. 1 – coarse filter up to 100 microns; 2 – pump; 3 – coarse filter up to 20 microns; 4 – aerator; 5 – compressor; 6 – filter with ion exchange resin; 7 – UV decontamination agent; 8 – fine filter up to 2 microns, including carbon

The water treatment system, as a rule, is installed after the hydraulic accumulator and automation. At first glance, it is more logical to place the filters before them, but it should be borne in mind that filters tend to clog, especially if they are not cleaned in time. In this case, according to the head / flow diagram, the pumping equipment leaves the working area: the shutdown signal is not received (the automation is installed after the filter), the pressure is high, and clogged filters interfere with normal performance – the pump overheats and fails.

The second scheme, in which the filters are installed in front of the accumulator, must include another pressure switch that stops the pump.

Installation recommendations

It is advisable to allocate a separate room for the installation of a water treatment system. A heating boiler and a hot water boiler can also be placed there..

All parts, according to the diagram, must be placed in series and connected with HDPE pipes or others of your choice. Pipes should slightly recede from the walls – 15–20 mm, for the convenience of repairing or replacing them. Wall-mounted devices can be fixed on a pre-fixed furniture board or special brackets. Installation of filters must be carried out according to the instructions or the passport attached to the device.

Install shut-off valves, pressure gauges, pressure switches. Connect the pressure and volatile filtering equipment to the mains, having performed grounding beforehand.

All plums must be embedded in the domestic sewage system. Flexible hoses must be clamped to stationary equipment or pipes.

After installation, you need to check the system for leaks and, in case of leaks, correct poorly made connections of the elements. All threaded connections must be seated on a seal (linen, fum tape), tightened, but not overtightened.

It is better not to drink the water entering the water supply immediately after starting the system. It is necessary to drain or use for household needs about 2-3 volumes of complete filling of the system.