Internal sewerage: device options in an apartment and a private house

Vasily Borutsky
Checked by a specialist: Vasily Borutsky
Author: Vladimir Blinov
Last update: March 2019

Properly connected internal sewerage in new housing is the key to the normal operability of plumbing equipment and the absence of unpleasant odors, and professional installation of pipes allows you to maintain the integrity of the new repair in the premises.

To make the right decisions in the process of laying sewers, knowledge of the schemes for its arrangement and the necessary materials is required. In this article we will tell you what the internal sewage system consists of and the basic principles of its arrangement.

Types of sewer pipes

For domestic needs, sewer pipes are made from various materials and different diameters.

Theoretically, the wider the diameter and the thicker the wall, the better the traffic and less risk of sagging pipes. But the aesthetics of appearance and price change the real choice of people when purchasing these products.

What material is used for manufacturing?

The material of sewer pipes depends on their durability and peace of mind.

Types of sewer pipes
The choice of material for sewer pipes is best done with a specialist. Cheap products can leak or deform quickly under their own weight

Cast iron sewer pipes have not been used in domestic sewers for a long time, their place was taken by plastic analogues, which can be made of the following materials:

  1. Polyethylene. Sewer pipes made of this material are flexible and sag, so their joints are difficult to seal. Polyethylene pipes are used in industrial sewers, where they are reinforced with transverse rings and used in areas with complex terrain. In the internal sewerage they are not used.
  2. Polypropylene. Quite expensive, but has good mechanical strength. Sewer pipes made of this material are heat-resistant, resistant to abrasive particles and perfectly tolerate cable cleaning.
  3. Polyvinyl chloride. PVC pipes almost do not differ from polypropylene in their properties, but they are a bit noisier and can bend when water flows over 70 degrees.

For apartment and house drainage is enough PVC pipes or polypropylene, which, if properly installed, will last several decades.

Diameters of pipes for sewage

There are standard diameters of sewer pipes that allow you to combine products from different manufacturers.

Popular sewer pipe diameters
The thicker the wall, the less pipes bend, so if they are long, it is recommended to purchase thickened products with increased stiffness

The most common when installing internal sewage pipes with a diameter of 40 mm and 50 mm.

For risers, a pipe with a diameter of 110 mm is used, but in multi-story cottages its size can be increased. For joining pipes of different clearance, adapters and nozzles of appropriate sizes are used.

Required diameters of sewer wiring
Minimum values ​​indicated. If there is a large amount of grease and waste in the drains, it is recommended to increase the pipe diameters to the next standard size

Pipe assembly technology

The procedure for assembling plastic sewer pipes is extremely simple and similar to a children's designer. Each of the pipes has a length of up to 3-5 meters, and their minimum size is regulated by a hacksaw for metal or special pipe cutter.

Connection diagram of sewer pipes
The smooth ends of the pipes should be well cleaned and stuck tightly into the socket, otherwise hair and fibrous product residues may accumulate at the inner joint

A purchased pipe or adapter has two different ends: smooth and with extension (bell). The simple end of the other pipe is inserted into the socket. To seal the connection in the extension there is a groove for installing the rubber ring. For better glide during installation, the seal can be greased with a thin layer of silicone.

Lubricate the rubber ring with sealant only during the final installation of the system, and not during the fitting process.

Tilt angle calculation

The peculiarity of the internal sewage system is that both insufficient and excessive slope of the pipes leads to their clogging. With a slight slope, solid particles settle to the bottom, not washed off by a weak stream of water.

With a large percentage of the slope, the clean liquid quickly leaves, and food particles remain and harden on the walls, which over time narrow the lumen of the pipe. The maximum allowable slope should not be more than 150 mm per meter pipe.

Compliance with the horizontal installation of pipes leads to the effect of "self-cleaning", in which solid particles are washed away by the flow of water into the riser, and they do not settle on the inner wall of the sewer.

Sewage Slope Design Data
The dimensions of the slopes indicated on the diagram can be increased by 25% without the risk of negative consequences, and it is not recommended to make the slope lower than these values

The indicated slope values ​​are calculated per meter of pipe, therefore, if a three-meter pipe with a diameter of 50 mm goes from the sink in the house, then the difference in its levels at the sewer riser and at the junction with the siphon should be at least 9 cm.

For more information on calculating the slope angle of sewer pipes, see this stuff.

Why do you need a water seal?

The smell of sewage remains in pipes and risers due to such a hydrophysical phenomenon as water seal. This is a water plug that forms in the siphon due to the drained water. She does not allow putrid smell to penetrate into the bathroom.

Types of plumbing siphons
To prevent drying of the water in the siphon during a prolonged absence in the apartment, it is recommended to pour a little vegetable oil into the sink or toilet bowl to reduce the evaporation area

If the sewer pipes have insufficient passability, then with a massive drainage of water, a water seal can break down. At the same time, due to the siphon effect, all water leaves the bend, and putrefactive air enters from the sewer into the room.

Internal drainage of a private house

When arranging and designing the internal sewerage of a country house, errors and shortcomings may occur, which are accompanied by the need to redo the already completed installation work.

Such situations can be minimized with the help of the following instructions and rules for planning and assembling the sewer system of an individual house.

Arrangement Highlights

The internal sewerage of the house has the form of a complex of plastic risers, pipes and fittings, which is used to drain wastewater from plumbing equipment and other devices that use water.

Scheme of the sewerage device of an individual house
The main element of the internal sewage system in the house is a vertical riser, which collects water from the rest of the horizontal wiring. In large houses there can be two of them for ease of installation and more free planning of room layout

The upper part of the riser is discharged above the roof of the house and is equipped with a special cover or valve that allows air to enter the pipe at the moment of water descent to prevent the siphon effect and breakdown of the water seal.

Plan of the sewage system of an individual house
The fan pipe according to the standards should be brought out on the roof to a height of not less than 50 cm from the roof surface

A ventilation banding scheme is also possible, in which the far edge of the outlet horizontal pipe is connected to the riser above the drain.

The riser is taken out of the house through the basement or underground space to the street in the well. From the vertical pipe comes the plastic wiring to the toilet, sinks and other equipment. Between the sewer pipes and plumbing there are siphons that prevent unpleasant odors from entering the room.

Sewer ventilation loop
Banding of ventilation makes sense only if there is no fan exit or its high height above the level of the horizontal wiring entry into the riser

Circuit Design Steps

If the layout of the house is not done by a specialized design organization, but by the owner yourself, then you should plan the layout of the kitchen, bathrooms and sewer wiring yourself.

A preliminary needs analysis will subsequently allow you to do the interior decoration of the rooms as you want, and not as circumstances force.

The procedure for designing the internal sewage scheme is as follows:

  1. Take the plan of the house on the land and determine the location of the sewage well. If the plumbing will be located on several floors, then the plan should be a floor.
  2. Mark the location of the vertical risers.
  3. Draw the location of all equipment that requires sewer.
  4. Draw horizontal pipes running from equipment to risers.
  5. Determine the diameter of the riser and the length of the fan pipe.
  6. Analyze the need to purchase plastic elbows, tees and adapters.
  7. To consider the possibility of a hidden sewage system and the need for decorative boxes.

In accordance with the drawn up scheme, then the installation of the entire internal sewage system will be carried out. The more carefully the plastic wiring plan is planned, the less problems there will be during its installation.

Planning calculations

To make a graphic image of the internal sewerage scheme of a country house is the key to avoiding major engineering errors. For the development of small parts, an accurate calculation of the parameters of the sewer system is required.

Therefore, it is necessary to take an already drawn diagram and analyze the following parameters:

  • calculate the length of horizontal plastic pipes and the ability to fulfill their slope standards;
  • calculate the required number and diameter of seals, connectors, adapters;
  • determine whether pumping equipment is required for the normal functioning of the sewer system;
  • calculate the maximum simultaneous flow through the supply pipes. A pipe with a diameter of 40 mm is usually sufficient for one device;
  • consider the need for an additional air circuit if the toilet drain is located above the level of other equipment in the horizontal wiring system.

Properly performed the above steps will make the sewage system effective and efficient even at maximum loads and minor blockages of pipes.

The sequence of plumbing installation work

When planning the construction of a house, it is necessary to focus on the following sequence of installation of its internal sewage system:

  1. The risers are installed, their ends are displayed on the roof and in the basement.
  2. Toilets for toilets are connected to the risers.
  3. A horizontal wiring is formed and one of its ends is connected to the riser.
  4. Siphons are connected to the plumbing.
  5. Plumbing fixtures are connected to the sewage system.

The organization of an external sewage system can be dealt with before or after the described actions.

After installing both systems, they are combined into one, connecting the internal risers to an external drain pipe.

Joint of external and internal sewerage
When laying the sewer through the foundation, it is inserted into a metal sleeve, which will prevent damage to the sewage system in case of precipitation of the house

Internal sewage in the apartment

The organization of internal sewage in a high-rise building is not much different from that in a country house, but still has its own nuances. You do not have to choose plastic wiring schemes, because the location of the risers and rooms is laid down in the general floor-by-floor scheme.

The principles of internal arrangement

Domestic sewage is based on the following principles:

  • the system works by gravity without the use of compressor units;
  • the entire sewer apartment scheme is closed on communal risers;
  • the basis of the system’s performance is compliance with the slope standards of sewage pipes;
  • ventilating fan pipes are used to equalize the intra-sewer pressure.

Compliance with all tenants of an apartment building of these principles when installing an internal sewage system allows neighbors not to worry about flooding and unpleasant odors in the bathrooms.

Features of the layout in the apartment

Changing the sewerage scheme in an apartment is quite difficult, because the toilets should always be located next to the vertical riser. Their movement by several meters will be accompanied by the need to lay 110mm pipes throughout the apartment, which will not add aesthetics to the appearance of the rooms.

Layouts of bathrooms in large apartments
In the majority of four-room (five-room, etc.) apartments there are two sewer risers due to the remoteness of the kitchen and the bathroom from each other

The arrangement of rooms and the number of sewer risers in high-rise buildings is limited only by the imagination of the designer, but they also try to comply with the basic rules for installing such systems.

Options with two bathrooms in domestic apartments are rare, but the kitchen and bath are divided by a corridor into two independent sewer systems. Then each room has its own vertical riser.

Pipe connection to the sewer riser
The interfloor space near the riser is not recommended to be completely filled with concrete. It is better to fill it with non-hygroscopic material, such as large pieces of foam, and then cover it with a small layer of cement on top

A separate 110 mm pipe always comes from the toilet. It can take in additional supplies from other plumbing equipment or be intended solely for flushing the toilet.

In the classical scheme, a sink is connected to the horizontal wiring at the far end of the pipe, then a bath or shower is attached, then a washing machine with a sink. After this, the pipe joins the tee of the toilet bowl or directly to the riser.

On the roof of all apartment buildings without fail a fan pipe is installed, which equalizes the air pressure in the riser and the interior of the house.

Installation procedure for sewer wiring

Before buying new plumbing in an apartment, you need to understand the future structure of the sewer network so that there are no problems installing the purchased plumbing equipment.

To do this, you must:

  1. Identify the types of plumbing fixtures and their installation location.
  2. Draw piping diagrams taking into account their inclination angles.
  3. Check the size and height of the holes in the walls for the installation of the planned wiring.
  4. Determine the number of products and materials for installation, purchase them.
  5. Perform trial installation of pipes and check the possibility of their installation.
  6. Dismantle the old sewer if necessary.
  7. Finally install sewer wiring.
  8. Install the sanitary equipment and connect it to the sewer.
  9. Check the resulting system for leaks.

If everything is done correctly, then after checking for leaks, you can use the plumbing for your pleasure.

Basic planning rules

When planning the scheme of internal sewerage, it is important to observe a number of rules that will help save time and ensure the durability of the assembled system.

Tips for arranging the riser and toilet:

  1. The toilet must have its own connection to a vertical riser. When connecting the device to the general horizontal wiring, a water seal can be disrupted in the nearby plumbing.
  2. The clearance of the riser pipe must be equal to or greater than the diameter of the toilet drain, but not less than 110 mm.
  3. In the riser it is necessary to provide special hatches for audits. The optimal height of their locations is 1000 mm from the floor.
  4. It is unacceptable to bring the edge of the fan pipe into the chimney.
  5. If the floor in the bathroom will be filled with cement, then the plastic riser is placed in a special plastic sleeve.

Rules for the design of horizontal wiring:

  1. The size of the drain pipe of the plumbing fixture should be less than the diameter of the water drainage pipe.
  2. The length of the drain pipe going from the toilet to the riser should not exceed 1 meter, from other appliances - 3 m. For larger pipes, it is necessary either to increase their diameter to 70 cm or more, or to loop pipes with vertical riser ventilation above the drain point.
  3. Do not connect horizontal pipes with rectangular bends due to the likelihood of clogging. It is better to connect them through two knees with an angle of 135 degrees.
  4. The socket of sewer pipes should be located towards the water flow.
  5. When installing the sewage system in closed ducts, it is possible to impose mineral wool pipes for sound insulation.
  6. Strobes for pipes in the bearing walls can be dangerous, therefore, its arrangement is possible only with the permission of the engineer.
  7. It is desirable to equip the drains from the dishwasher and sink grease traps.
  8. When connecting plumbing equipment, it is necessary to turn the lower edge of the tee by half the height of the socket.
  9. Long plastic pipes must be secured with clamps to prevent sagging.

After the installation of the internal sewerage is completed, it is necessary to fill the sink and sink to the brim with water, open the drain hole, and also conduct a complete drain of the toilet.

If there are no leaks and unpleasant odors, then most of the rules are followed.

Conclusions and useful video on the topic

For visual familiarization with the correct planning of the location of sewer pipes, it is recommended that you watch the following videos.

Designing a fan pipe in a private house:

Rules for the arrangement of internal sewage:

The nuances of the internal sewerage in an apartment building:

The presented options for placing sewer pipes in housing are typical. The importance is not in copying the proposed options, but in observing the rules and principles of planning and installing the sewer system. Only their observance can eliminate the need for additional repairs due to leaks and equipment mismatch with sewage parameters.

Have questions, find flaws in the article, or have personal experience in arranging the internal sewage system? Please leave your comments, ask questions, share your experience in the block below.

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Visitors Comments
  1. Valentine

    The mother-in-law in the old house simply had some kind of horror with sewage - they screwed it up with a tilt angle and with a water lock, in short, I don’t know which genius it mounted. The result is deplorable - when washing with a typewriter, sometimes part of this water got out into the bathroom and sink, often there were smells of something rotten, i.e. sewers. I had to redo everything, because the unsanitary conditions turned out to be complete!