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Filter well: purpose and device

Many people who live in private homes and do not have access to centralized sewerage are faced with the problem of wastewater disposal. It can appear in the countryside, in the suburban area and in the city. Today there are several ways to solve this problem. The choice of a particular one depends on such factors:

  • domestic water volume;
  • soil type;
  • ground water level;
  • estimated budget of works and others.

But there is a universal way to dispose and treat wastewater in a separate private area - this is a filtering well for sewage. It consists of special filters, through which water is purified and enters the ground. You can build a well on your own without big financial expenses.

A filter well is understood as a special underground building that performs the function of biological purification of domestic water. It is simply impossible to do without such a design if there is no possibility of utilizing water in another way on earth. Wastewater includes both domestic water and after rain, snowmelt. If the site does not have a slope, then surface water lingers on it and brings great inconvenience.

The filter well does its job best on such soils:

  • sandy;
  • peat;
  • sandy loam.

Wells can be used as a full-fledged structure for water drainage, as well as an auxiliary one. As the main structure, a filter well is used when the daily volume of such a liquid is not more than 1 m 3. The well acts as an additional structure if auxiliary purification of water is needed, which then enters the ground.

The principle of operation of the well is simple. Through a special tube, water from the house enters the settling chamber. It is especially necessary if the house has a toilet. Then all the fractions will not settle at the bottom. A little above the bottom of the chamber there is an opening through which domestic water flows into the well, where it falls to the bottom of the filtration. It consists of pebbles, and after passing them, the water is significantly purified, and then gradually seeps into the soil.

Location and dimensions of the well

Before you start building a filter well with your own hands, you need to take into account such important features:

  1. The mine should be located away from the house and outbuildings. The distance from it to the nearest foundation should be at least 10 meters.
  2. If there is a well with drinking water on the site, then a distance of 25 meters or more must be maintained from it.
  3. The level of groundwater matters. Between them and the bottom of the shaft must remain 1 meter or more.

The device of the filter well has an area depending on the amount of wastewater and the type of soil. For example, sandy soil with an area of ​​​​1m 2 can filter about 100 liters of water per day, and sandy loam - half as much. These data should be the basis for determining the size of the future structure. Of course, there are some restrictions on its size in a limited area. The depth of the filter well should not exceed 2.5 meters, this is with a total area of ​​​​2 m 2. But if the calculation results in an area greater than this value, then several wells must be made. This happens quite often when the land or house is very large. They must be placed at a distance of at least two of their own diameters.

The construction of drainage wells on rocks is not recommended, since in such soil the water is not filtered and can end up in clean groundwater. The filter well will also be ineffective for clay soil.

Filter well device

The well for filtration consists of:

  • bottom filter;
  • walls;
  • surface overlay.

Consider in stages the main components and rules for the arrangement of each element.

  1. Bottom filter. Filter wells design must consist of a high-quality bottom filter that purifies water before it enters the ground. In the intended place where water will fall from the pipe to the filter, you need to install a small wooden shield that prevents the bottom from washing out and evenly distributes water over the entire surface. After backfilling, there will be a distance of 20-30 centimeters between the filter and the pipe. As a backfill for the bottom filter, use:
  • crushed stone;
  • gravel;
  • expanded clay;
  • battle of bricks and stones.

The maximum size fraction should not exceed 70 mm in diameter. Backfilling should be done with a height of about 1 meter. Even if a settling chamber is used, a small amount of organic sediment will still form on the surface of the filter. Over time, it is gradually destroyed by microorganisms. It is not allowed to clean the filter well with bleach or other chemicals. To do this, once every couple of years (depending on the workload of the mine), you need to clean it with a special sewage machine or pump.

  1. Walls. A variety of materials are used to equip the walls, for example, bricks, reinforced concrete rings, and so on. Often there is even a plastic filter well made from an old large barrel. But the plastic must be strong enough so that the earth does not crush it over time. Between the ground and the walls, you can make a small fence, which is then filled with heat-insulating material. Very popular is a metal filter well from a pipe. In this case, you also need to pay attention to the thickness and quality of the metal. In this case, you will need to drill holes, which complicates the work a little.

The easiest option is to make a filter well from ready-made concrete rings, which are very strong and durable. In the walls you need to make small holes, about 4-6 cm in diameter. They should be done in a checkerboard pattern 10 cm apart. If the walls are made of brick or stone, then they are simply placed at a short distance from each other. There are already holes in the specially provided concrete rings. Externally, the filter well is filled with the same material, no more than 40 cm thick, and at the height of the filter.

  1. Overlap. The absorption filter well must necessarily have not only a reliable overlap, but also ventilation. The latter is made in the form of a small pipe (diameter up to 10 cm) in the ceiling. It should be closed with a grate externally and be 70-100 cm above the ground. This height is especially necessary in winter, when snow can close the ventilation. Of course, such a pipe can negatively appear on the landscape, but it can be hidden by plants or painted in an interesting color.

The filter well device should have a hatch with a diameter of approximately 70 cm in the ceiling. There are two covers in it:

  • carrier, located on top;
  • weighting, located below.

If in winter the temperature drops to -20 degrees and below, it is necessary to protect the container from freezing. Otherwise, the backfill mixture with water will freeze and will not perform its function, and the mine will simply be flooded with domestic water. To ensure thermal insulation, the space between the covers is filled with any materials, such as foam, mineral wool, burlap and others. Additional protective materials can also be placed on top of the ceiling. It is also necessary to provide good thermal insulation for pipes from the house to the mine, because they lie at a shallower depth, so they can freeze in winter.