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DIY design and installation of a private house sewage system

This DIY post guides the reader through the design and installation of a private house sewage system. It explains the materials and tools needed, as well as the step-by-step process of installation. The sewage system is reliable and designed to last for several years, as well as being cost-effective, with significant cost savings compared to professional installation. Furthermore, installing the system on your own is a great way to save time and learn the basics of self-maintenance.

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Even when planning the construction of a private house, it is necessary to complete a wiring project and equipment for external and internal sewage. What must be taken into account when designing a system, what equipment should include such a project and how to carry out the installation โ€“ questions that we will try to answer in this article.

DIY design and installation of a private house sewage system

It is difficult to imagine the construction of a modern private house without sewage equipment. Even in old houses, the comfort level can be improved by carrying out appropriate work.

State regulation and recommendations

Before starting the development of the project, we advise you to familiarize yourself with the MDC 40-2.2000 Manual. This is an extremely useful compilation for the development of autonomous engineering networks of a private house with a large volume of requirements, definitions, mandatory and recommended system parameters..

Also useful and will be useful:

  1. GOST 25150โ€“82 โ€“ terms.
  2. SNiP 2.04.01โ€“85 โ€“ for the development of internal sewerage.
  3. SNiP 2.04.03โ€“85 โ€“ for the development of external sewerage.
  4. SP 31-106-2002, p. 5 โ€“ sewerage of single-family houses.

In the text of these documents, you can find and clarify controversial or doubtful points that arise during the design.

Collection and analysis of initial data for design

The design of sewer networks requires some preparation, which consists in drawing up a technical task, even if the work is carried out independently. So you donโ€™t have to redo the work several times..

List of source data to be prepared:

  1. System type: autonomous or connecting. To insert into the centralized sewerage system, you will need documents for the house and permission to perform the tie-in.
  2. With an autonomous system, you need to decide on the disposal method (biological station, septic tank, sealed storage, cesspool).
  3. Geological data: the depth of soil freezing, the depth of the aquifer, the location of reservoirs, the location and depth of a well or well (with autonomous water supply), soil data.
  4. Precipitation data (for storm sewer design).
  5. Based on the recommendations of SNiP, calculate the peak load, which depends on the number of people living and plumbing equipment. If living in the house is seasonal, this is also taken into account in the calculations..
  6. Draw up a floor plan showing drainage points from bathtubs, showers, sinks, sinks, toilets, bidets, washing machines and dishwashers.

Sewerage scheme in a private house

Internal sewerage design

We start designing with the location of the plumbing equipment. To reduce the length of the sewer pipes, as well as to simplify the ventilation of the system, it is recommended to place them as close to each other as possible, and when placed on different floors, one above the other. Thus, the riser is a vertical section of the drainage system, there will be one in the house. With a large area of โ€‹โ€‹the house or in the case when sewage is carried out in an existing building, it is possible to equip two or more risers.

Household sewerage device

All drains from individual points are cut into the riser with pipes with a diameter and slope recommended by SNiP. These recommendations make it possible to skip hydraulic calculations in most cases. The specified slope value is the minimum. The maximum value is 15 cm / m (except for areas shorter than 1.5 m โ€“ there can be more).

Table. Required slopes and diameters of pipes for discharge

Device Slope Distance between central drain and siphon without ventilation, cm Pipe diameter, cm
Bath 1: 3 100-130 40
Shower 1:48 150-170 40
Toilet bowl 1:20 up to 600 one hundred
Sink 1:12 0-80 40
Bidet 1:20 70-100 30-40
Washing 1:36 130-150 30-40
Bath, sink, shower (combined drain) 1:48 170-230 50
Central riser one hundred
Bends from the riser 65-75

Table. Slope values โ€‹โ€‹depending on the pipe diameter

Pipe diameter, mm Slope, cm / m
40-50 3
85-100 2
150 0.8

Pipes are routed using shaped joints. In this case, it is desirable that the bends consist not of one elbow at an angle of 90 ยฐ, but of two at 45 ยฐ (or 3 at 30 ยฐ). This reduces the local hydraulic resistance, reduces the likelihood of clogging..

Sewer pipe bends Execution of bends: 1 โ€“ 30 ยฐ bends; 2 โ€“ fastening clamps; 3 โ€“ overlap; 4 โ€“ oblique tee or revision

The upper part of the sewer riser (drain pipe) is brought out above the roof level by at least 50 cm and is open for ventilation and compensation for pressure drops during the period of draining from one or more points. Aeration valves are installed on dead-end risers that do not go out onto the roof. The lower part of the riser falls below the floor of the first floor, preferably into the basement, and is removed by a pipe of the same or larger diameter outside the house.

Private house sewerage ventilation Sewer system ventilation device: 1 โ€“ deflector; 2 โ€“ aeration valve; 3 โ€“ riser with a diameter of 110 mm; 4 โ€“ riser with a diameter of 75 mm

The principle of operation of the sewage aeration valve The principle of operation of the aeration valve: A โ€“ the valve is closed; B โ€“ the valve is open

Aeration valve on the riser Aeration valve appearance

Internal sewerage design rules

For the normal functioning of the system, you should strictly adhere to some rules for the design and arrangement of the sewage system:

  1. The location of the toilet should be as close as possible to the riser (no further than 1 m). The drain from it must be individual; it is inadmissible to connect the drain from another source. All other plumbing fixtures on the floor that drain water into the same riser should cut above the toilet drain..
  2. The diameter of the drain pipes cannot be less than the diameter of the equipment drain hole.
  3. The maximum permissible length of a conventionally horizontal section should not exceed 10 m (ideally, no more than 3 m). At large distances, a second riser is organized. The longer the horizontal section, the larger the diameter of the sewer pipe should be, not less: over 3 m โ€“ O 70 mm, over 5 m โ€“ O 100 mm.
  4. In all cases, the recommended slope must be maintained.
  5. On long sections of pipes, both horizontal and vertical, it is necessary to install revisions for cleaning in case of possible blockage.

DIY design and installation of a private house sewage system

Outdoor sewerage design

The main issue in the design of an external sewage system is the choice of a waste disposal method.

The choice of a sewage disposal system

If there is no possibility of connecting to a centralized backbone, choose one of the options.

Cesspool

It is not intended for the disposal of a large volume of liquid effluent from a bath, shower, etc. and is most often equipped only for draining the toilet bowl (powder closet). If, at the same time, the exit of the sewer pipe outside the house may be lower than the filling level of the pit (for example, during the period of rains, melting snow, a water supply accident), then a check valve must be installed on the pipe.

Check valve on the sewer pipe Check valve at the sewer outlet

Sealed storage

It is a purchased or self-assembled container into which all the drains are poured: from the toilet, and from the bath, and from the washing machine. Periodically requires emptying, for which they order a sewer truck. The most budget-friendly option in initial spending, but requires regular maintenance costs.

Storage tank for sewage Sealed storage tank for sewage

The storage tank must be equipped with a hatch for inspection and pumping out sewage.

Septic tank

It is a sealed tank consisting of one, two or three compartments (sections). On the one hand, a branch pipe is provided for connecting to a pipe from the internal sewage system of the house, on the other โ€“ a branch pipe for purified (clarified) water.

According to SNiP, the type of septic tank is accepted:

  • one-section, with a volume of at least 3 m3 โ€“ up to 1 m3/ day;
  • one-section, volume not less than 15 m3 โ€“ up to 5 m3/ day;
  • two-section, with a volume of at least 25 m3 โ€“ up to 10 m3/ day;
  • three-section, with a volume of 2.5 times the daily consumption โ€“ more than 10 m3/ day.

Three-section septic tank scheme Three-section septic tank. Zone A โ€“ primary settling tank; zone B โ€“ anaerobic reactor; zone C โ€“ final clarifier

Due to anaerobic bacteria (bioferments that live and work with a lack or absence of oxygen), organic matter goes through several stages of fermentation, as a result of which it decomposes to silt, gaseous substances discharged into the atmosphere, and relatively clean water, the final purification of which takes place outside the septic tank in the soil โ€ฆ With a properly selected septic tank, after some time in the tank, biological equilibrium is established, which does not require the addition of bioferments.

Soil post-treatment, in the case of a sanitary ban on draining wastewater immediately after the septic tank, should consist of the installation of perforated drainage pipes, laid with a slope from the septic tank on a layer of rubble and covered with sand, which act as natural filters. At the end of the channel, you need to equip a ventilation pipe, raising it above the soil level not lower than 70 cm.

Ground wastewater treatment Soil post-treatment scheme: A โ€“ absorbing trench for sandy loam and sand; B โ€“ filtering trench for clay and loam; 1 โ€“ crushed stone; 2 โ€“ final backfill; 3 โ€“ absorbent pipes; 4 โ€“ filtration sand; 5 โ€“ drainage pipes

For sandy loams and sands, it is possible to arrange a filter well made of bricks or concrete rings, the bottom of which is covered with a layer of gravel about 1 m deep. In this case, groundwater should not be closer than 0.5 m from the lower boundary of the gravel. The larger the diameter of the well, the longer it will last. Roughly the cross-sectional area should be:

  • 3.0 m2/ 1 person โ€“ with sandy loam;
  • 1.5 m2/ 1 person โ€“ in the sand.

Installation diagram of a three-chamber septic tank with a well Filter well after a three-section septic tank: 1 โ€“ backfilling; 2 โ€“ concrete pad; 3 โ€“ septic tank; 4 โ€“ insulation; 5 โ€“ brick well; 6 โ€“ crushed stone; 7 โ€“ sand

In the presence of large areas, low-lying groundwater and a significant amount of additional treatment, after the septic tank, you can arrange a filtering field, which is a layer of crushed stone at a depth of about 1 m, covered with sand.

Installation diagram of a three-chamber septic tank with a filtration field Filtering field after a three-section septic tank: 1 โ€“ backfill; 2 โ€“ concrete pad; 3 โ€“ septic tank; 4 โ€“ insulation; 5 โ€“ crushed stone; 6 โ€“ sand

Biological filtration station

The principle of operation of the station is similar to a septic tank, but aerobic bacteria and microorganisms (requiring oxygen for life) act as a fermentation catalyst. Due to the higher oxidation rate, the decomposition of organic matter occurs faster, and therefore the capacity of the station can be more compact than that of a septic tank. To keep bacteria alive and maintain a high fermentation rate, air is constantly supplied to the tank through a compressor, which requires constant supply and energy costs. As well as for a septic tank, long station downtime affects its operation negatively.

Biological treatment plant layout Biological filtration station with aeration tank: A โ€“ receiving chamber; B โ€“ aerotank; B โ€“ secondary settling tank; G โ€“ sludge settler; 1 โ€“ deflector; 2 โ€“ compressors; 3 โ€“ airlift for pumping water into the secondary clarifier; 4 โ€“ airlift for pumping sludge into the sump; 5 โ€“ airlift for pumping contaminated water; 6 โ€“ overflow hole; 7 โ€“ coarse filter; 8, 9 โ€“ aerator

Since fats, washing powder and detergents inhibit the vital activity of both anaerobic and aerobic bacteria, sometimes plums from different sources are separated. From the kitchen and from the washing machine, water is removed to a storage bin for periodic removal, the rest of the effluent is sent to a septic tank or biological treatment station. Other combinations of treatment facilities are possible โ€“ in several stages, for a deeper degree of purification.

Allowable distances

All external sewerage channels must also be carried out with the recommended slope. The device of treatment facilities must take into account the location on the site and outside of the points of water intake, utility and residential buildings, perennial plantations, reservoirs.

Allowable distances are determined on the basis of SNiP and depend on the performance and type of treatment plant.

Distance of buildings from the septic tank Allowable distances: 1 โ€“ outbuilding; 2 โ€“ cellar; 3 โ€“ well; 4 โ€“ septic tank

Sewerage installation

After the development of the project and the purchase of all the necessary materials and equipment, the time for installation comes. These works are carried out before the start of finishing, in order to make adjustments during the start-up of the system and it was possible to hide the piping.

DIY design and installation of a private house sewage system

Internal pipes are bred according to the developed scheme, maintaining the necessary slopes and equipping the risers with a ventilation system. Particular attention is paid to connecting the toilet, avoiding long leads, turns and any resistance on the way to drain into the riser. All drains from sinks, baths, etc. are carried out through siphons โ€“ this way you will avoid an unpleasant smell from the drain holes. If, as a result of finishing work, the pipes will be sewn into boxes, provide for opening inspection hatches.

When working with pipes, they need to be cut and connected: for example, as shown in the figure.

Sewer pipe connection diagram

For the laying of external pipes and installation of cleaning equipment, all earthworks are performed at the first stage. Precisely maintain the specified distances and slopes, and when organizing additional soil cleaning โ€“ the thickness and area of โ€‹โ€‹the backfill layers. Alone, these works are difficult, and sometimes even impossible. For example, for the installation of a heavy septic tank or biological treatment station, the installation of concrete rings, etc., special equipment may be required..

DIY design and installation of a private house sewage system

When joining pipes that may heat up in summer, leave small (up to 10 mm in length) gaps between the pipe and the socket for thermal expansion or elongation due to ground pressure. The junction of the sewer pipe with the entrance to the sewage treatment plant must be sealed and strengthened โ€“ it can be done with a strong rope soaked in solid oil.

In conclusion, watch useful videos with tips for laying and joining the sewer of a private house.

Video 1. Laying sewer pipes

Video 2. Joining of pipes with different cross-sections

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Comments: 2
  1. Everly

    What are the key considerations and steps involved in designing and installing a private house sewage system for DIY homeowners?

    Reply
  2. Wyatt Palmer

    Are there any specific regulations or permits required for the DIY design and installation of a private house sewage system? Additionally, what are the key considerations and best practices when it comes to ensuring proper functionality and compliance with environmental standards? Thank you in advance for any guidance or insights!

    Reply
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