Laying sewage in the house. Laying sewer pipes in the ground: technological rules and nuances

From internal pipelines, effluents are transported through external pipelines to storage tanks or septic tanks. In order for this function to be performed at the proper level, it is necessary to ensure the correct laying of the pipes.

Most often for mounting sewer network  use polymer pipes made of polypropylene, polyethylene and polyvinyl chloride, painted in orange.

In the presence of dynamic loads exerted on the pipelines of the network. It is worth choosing corrugated polymer pipes consisting of two layers of material. The connection is made using fittings, usually in the socket. Such pipelines are less susceptible to corrosion, durable and due to the low roughness of the walls do not create blockages and fouling. They are laid to a depth of less than 3m.

Pipe Sequence

1. Excavation. First you need to dig a trench correctly, only then begins the laying of sewer pipes in the ground. The technology of this process is as follows:
   • Determination of the depth of the trench - in accordance with regulatory documents, it should be greater than the depth of freezing of the soil in winter, and the location of groundwater should also be taken into account
   • Trench preparation - leveling the bottom surface, a slope is performed according to the calculations (usually 1-2 cm per linear meter), a substrate of crushed stone with a thickness of 15 cm is poured and compacted, and small pits are made at the moments of connecting the pipelines and fittings
2. Construction works. Lay pipes should start from the foundations of buildings:
   • Laying pipelines in trenches with the socket down and cleaning their edges
   • Lubricate the edges with a special substance and insert the pipe into the socket until it stops
   • The connection of all other parts

   For the convenience of the work, the correct and reliable connection of pipelines, it is necessary to measure the depth of the pipe entry into the socket in advance and put the appropriate marks.

   Turns on the trunk line are constructed in the amount of 15, 30 and 45 degrees. Every 15 meters of the pipe is equipped with a revision or cleaning.

3. Backfilling of the trench is the final stage of construction work, after the laying of sewer pipes in the ground has been completed. Backfill technology provides for checking the angle of inclination of the system after connecting all the elements. In order to fill the trench, the soil used is formed during the excavation, which is first crushed and gets rid of large inclusions.
   

   For backfilling, it is forbidden to use the soil, which contains stones or solid blocks larger than 30 cm, as they can damage the sewer pipes.

   The trench is gradually filled with earth, each layer about 5 cm thick is rammed in the embankment only in the lateral part of the pipelines. It is forbidden to ram over them, since the possibility of deformation or damage to the pipe is not ruled out.

Sewer pipe insulation

Pipelines in need of warming are usually those that are located above the freezing mark of the soil or releases from the internal sewage system. Typically, for these purposes, polymeric heaters such as stenoflex or energy flex are used. Thermal insulation is placed around pipelines and is well fixed by couplers or wire. Only after installing the insulation and checking the slope of the network, you can backfill the trench.

It should be remembered that if there are breakdowns in the sewer network, it would be more expedient not to change a separate element that has failed, but to completely dismantle the system. It will be more reliable and economical.

The process that you can perform yourself is the construction of the system and the laying of sewer pipes in the ground. Its technology is simple, and if you follow all the recommendations described in this article, the life of the sewage system will be long, and its reliability will be high.

When building any modern home it is necessary to take care of the sewage system. Installation of pipes for sewage should be carried out in compliance with all norms and requirements. This will make it possible to avoid future replacement of deformed pipes, time-consuming cleaning, excessive noise during the movement of waste fluid and other troubles associated with the operation of the sewer.

Sewerage installation at home

During installation, gray pipes made of PVC or PP are used for it. These pipes have a lower strength class than orange for outdoor sewage, since they are not subjected to such a high load as the latter.

The use of gray pipes for the installation of external sewers is strictly prohibited. For sewage at home, pipes are most often used, the diameter of which is 40, 50 or 110 mm. The laying of the internal sewage system can be divided into two stages. The first is the installation of vertical and horizontal pipes under the floor or in the basement. Simply put, pipe wiring is being designed.

Before starting work, it is necessary to mark the axes of the pipelines and the places where the fasteners will be located. Then mounts are mounted and ready-made assemblies are assembled from nozzles, fittings and pipes. Finished nodes are interconnected, check the correctness of their location relative to the vertical and horizontal, and then mounted in the clamps.

At installation of the sewerage  it should be borne in mind that it is impossible to place bell-shaped joints in places of passage through floors and other building structures. It is also forbidden to change the slope in the horizontal outlets. The installation of vertical risers must be carried out from the bottom up without vertical deviations. When this work is done, you need to design risers and horizontal outflow lines. This stage ends with the installation of an exhaust part of the pipeline in the attic.

Pipeline installation

The next step is the installation of horizontal pipelines on the floors of the building with their connection to the releases of sanitary appliances and siphons. When carrying out these works, it is allowed to mechanically process pipes and nozzles using hand saws for metal and hacksaws for wood with small teeth.

It is necessary to saw the pipe strictly perpendicular to its axis. The resulting burrs must be removed and chamfered with a large serif file. All the above types of processing can also be carried out using special tools. Machining fittings (tees, turns) mechanically is prohibited. It is also prohibited to lubricate the pipes during installation with machine oil, solid oil, etc. Allowed only the use of soap solution or special lubricants.

When fitting fittings and pipe bells must be directed against the movement of wastewater.

Sewerage installation prices

Sewerage installation inside the house

It must be designed in such a way as to compensate for the possible extension of the pipeline during operation associated with a change in temperature. Pipes can be extended by a maximum of 10 mm to 2.5 meters of pipe. To compensate for such elongations, the bell-shaped connection is installed so that the pipe with a smooth end does not reach exactly 10 mm to the stop.

For pipes with a length of 2.5 to 10 m, special couplings are used for compensation - compensatory, which allow you to compensate for up to 60 mm of elongation. Now, when the installation of internal pipes for sewage is completed, we will talk about external sewage. To install pipes for external sewage, smooth pipes of the orange outer surface of PP (polypropylene) and PVC (polyvinyl chloride) are used.

Ginger-colored sewer pipes do not undergo destruction and corrosion, being underground, just like gray ones. This is due to the fact that they have such a very smooth inner surface. In production, special additives are added to these pipes, which makes them more rigid and allow them to withstand large external loads. The laying of such pipes is possible even at a depth of 3m.

If a very high load on sewer pipes is planned (namely, the location under the roadway or their deep bedding), then pipes with increased stiffness are used, namely, two-layer corrugated pipesmade from PE (polyethylene) or PP. The most common among sewer outdoor plastic pipes are pipes whose diameter is 110 mm. IN suburban construction  these pipes are universally used for the removal of effluents from one small building as well as from a whole group of buildings to sewage treatment plants. Sewer pipes of large diameters are also used - for larger wastewater disposal. When designing sewers, special shaped elements are used to connect plastic pipes.

Pipe installation in trenches

The second way is to trench manually. When installing pipes with a diameter of 110 mm (the most common), the width of the trench should be the same as in the first case. The installer, who will perform the laying work, must stand with two legs (freely) in the trench. Upon completion of the work, it is necessary to level the bottom of the trench and set the required slope for it. It is necessary to dig a trench so that its depth is approximately 50 mm greater than the depths at which, according to the plan, the pipe should lie. This is necessary in order to prepare a sufficiently dense sandy base. In both cases, the sand is poured to a height of 50 to 100 mm and compacted by hand.

When the trench is dug up and the sand cushion is filled up, orange sewer pipes are prepared. The internal elements of the sockets must be freed from contamination and the presence of o-rings in the pipes must be checked.

The installation of sewage should begin from the foundation. If the pipe was removed from the house while laying the foundation of the building, then the outer sewer pipe is worn with a bell on the smooth end of the outlet pipe. Otherwise, the pipe is inserted under the foundation or a hole is drilled for it (using diamond drilling).

Sewer pipes and fittings are connected by silicone grease or liquid soap. The smooth end of the pipe is lubricated and inserted into the bell with rubber.

Then, on a prepared sand base, lay a sewer pipe with a slope of 2 cm per 1 m (pipe diameter 110 mm). The first pipe of the external sewage system is connected to the sewer pipe of the internal sewage system leaving the house. To change the direction of movement of wastewater, smooth (15, 30, 45 degrees) bends for external sewage pipelines are used.

If the length of the sewer route is more than 15m, then at every turn it is necessary to provide for the presence of a revision.

It is necessary that the pipes, unlike the pipes of the internal sewage system, are connected all the way, because expansion of pipes is possible due to temperature changes.

Docking of pipes is always done manually. To ensure that the pipes are easily and airtight connected, the smooth end of the pipe is carefully cleaned from sand and dirt, and the bells and o-ring are cleaned. The ends are lubricated with soap or silicone grease.

After the pipes have been connected, check their slope and fill them with sand with a layer-by-layer tamper from the sides. Sand is not rammed directly above the pipe.

Along the entire length, the slope of the pipes should be 2 cm per 1 m. This is explained by the fact that only with such a slope a smooth flow of liquids is ensured together with the substances contained in it, and the probability of clogging in the pipe is significantly reduced.

To insulate sewer pipes, they use a specially designed energy-flex insulation (or stenoflex) - it is also foam polyethylene.

Energoflex is put on pipes along the entire length of the sewer route. The insulation on the pipes is used to prevent freezing of wastewater.

Warming of sewer pipes is necessary if they are laid within the depth of freezing of the soil.

When the energoflex is dressed in pipes, make a control measurement of the slope of the pipes. Then make backfill from the sides with tamping and final backfill with sand.

After this, the pipe must be completely covered with soil remaining when digging a trench. Soil is poured with a hill (to a height of 10-15 cm), because over time, it shrinks. Usually, after the pipes are filled up with sand, an electric cable designed to power the treatment plant is laid next to the trench. The cable must be laid in a protective corrugation. The pipe is connected to the septic tank according to the installation instructions of the station used.

After all the above operations have been completed and the station has been prepared for operation, the treatment plant is ready for operation. Masters must carry out a control check of the compressor and pump, as well as check the operation of airlifts.

The treatment plant is put into operation, the operability of the pipeline is checked for the supply of wastewater and, accordingly, the discharge of treated water. When all this is done, the sewage system is ready for use.

All land work during the construction of the sewage system, drainage, fixing the walls of trenches, water reduction should be carried out in accordance with the regulation SNiP 3.02.01-87. You can find a list of some requirements from the regulation below.

In suburban homes there is no centralized sewage system, so the owners of such houses have to independently build an autonomous drainage system on their site. Laying sewer pipes in the ground is not particularly difficult, however, there are certain norms and rules that must be taken into account when working.

Today, in almost every household there is a necessary set of amenities for a comfortable stay: wash basin, sink, toilet, shower or full bath, washing machine and other benefits of civilization. Many houses are equipped not with one, but with several bathrooms and bathrooms.

All this economy, when fully operational, produces a large amount of waste and wastewater per day (according to standards, the amount of liquid waste per day per person is from 5.4 to 9.5 liters), which must be discharged somewhere.

As a rule, country houses, where people live permanently, have many different plumbing devices, which makes it necessary to equip an autonomous sewer system

Therefore, the drainage system is an indispensable part of the engineering communications of an individual house. It consists of an internal sewage system, a discharge from a residential building and an external sewer network laid on the site.

Many owners of private houses, paying particular attention to the internal house system, for some reason do not always properly treat the arrangement of external networks. Indeed, the process of laying the pipeline seems simple, it is enough to dig a trench, dock the pipes with each other, the house system and the collector, and then fill it with earth.

But this is only at first glance. In fact, in this, as in any other work, there are many nuances that must be taken into account. Non-compliance with technological standards and improper laying of the pipeline may lead to siltation and other considerable problems in the future.

In order for the sewer system to function smoothly and for a long time, it is necessary to adhere to construction and technological standards when it is installed (+)

The drainage system should ensure the discharge of all wastewater, exclude the possibility of flooding the building in the event of an emergency, and guarantee the treatment of effluents when they are discharged into the water body. When arranging the system, it is necessary to take into account such parameters as the material of manufacture and the diameter of the pipes, the type of soil in the area, the depth of the sewer pipes, a certain angle of inclination.

Autonomous sewage of private households can be made in the form of separate or joint removal and treatment. In the first case, two separate pipelines are made from the toilet for wastewater from washbasins, bathtubs and sinks and for fecal matter. In the second case, all liquid and solid wastes are combined into one common stream and enter the septic tank, where they undergo a cleaning process, and then are exported.

The choice of pipes for laying

Previously, when laying sewers, only metal pipes were used: cast iron or steel. Indeed, these materials, like no other, are suitable for laying in the ground. They are strong, durable, have a low cost, easy to install. However, along with the advantages, metal structures have significant disadvantages. The downside of steel pipes is the possibility of corrosion, and cast iron - a lot of weight.

There is no equal in strength and durability to cast-iron pipes, this material can lie in the ground for decades without losing its qualities, but because of their severity, the laying of a water conduit is much more complicated

A certain difficulty is the sealing of the joints of a cast-iron pipe, as well as its inner surface, which, due to the characteristics of the material, will never be perfectly smooth. The latter characteristic affects the speed and quality of movement of waste within it, with time blockages can form in the pipe.

Asbestos-cement pipes can be used for laying sewers. They have a smooth surface, which eliminates the possibility of clogging, they simply connect using special couplings, their weight is much less than that of metal structures. But they also have a significant minus - great fragility, which complicates their transportation and installation. Ceramic pipes have the same fragility.

Reinforced concrete structures have many advantages: they have exceptional strength, water resistance, and frost resistance. It is possible to make large diameter pipes from reinforced concrete, which cannot be made from other materials. But laying such pipes is a big problem. Because of their heavy weight, it is necessary to use special equipment, which is not always advisable in an individual farm.

Today, when arranging the sewerage of a private household, polymer pipes are most often used, which, for all their strength, are lightweight, which allows them to be laid by one person. They are very simple and easy to connect, with excellent tightness.

For the arrangement of external sewage, orange polymer pipes are used. They have increased strength compared to gray pipes designed for internal piping, and also have the ability to withstand heavy loads

Polymer pipes come in three types: PVC, polyethylene and polypropylene. PVC structures, in addition to the above advantages, are also resistant to UV radiation and a slight change in parameters during temperature changes. However, they poorly withstand very low and very high temperatures, and can also deform under mechanical stress.

The sewerage system during its operation is subjected to dynamic loads that best withstand corrugated polyethylene or polypropylene pipes. Even when freezing, the integrity of the pipe will not be broken, but deformation of its walls can occur.

The diameter of the pipes is selected based on the number of plumbing equipment installed in the house. So, for a country cottage with two toilets, 110 mm section pipes will be enough. If there are three or more bathrooms in house building, it is necessary to use a pipeline with a diameter of 160 mm.

Sewer installation depth

Some mistakenly believe that the deeper the sewage system will be located, the more efficient it will work. However, it is not. The system’s performance will not increase from this, the only thing that will increase is the cost of laying it. In addition, the maintenance of the sewer network will become more complicated. And the biggest trouble can happen if, as a result of heaving or washing the soil, the pipes will not withstand its pressure and burst.

When laying sewer pipes, it is necessary to adhere to the norms and rules enshrined in SNIP 2.04.03-85. An important parameter that must be taken into account when installing the pipeline is the depth of its occurrence in the ground. Despite the fact that the normative act does not provide clear parameters for the depth of the pipes, the document indicates which criteria are determining when laying the sewer line.

Usually in central Russia, pipes are laid to a depth of 0.8-1.4 m, which is quite enough for the effective functioning of the sewage system

According to the SNIP, it is necessary to be guided by the climatic conditions characteristic of the region, in particular the level of freezing of the soil, and the experience gained in operating the sewer networks in the area. If there is no information about the operation of the sewage system, then the minimum depth of the pipeline should be 30-50 cm above the freezing level.

At the same time, there should be a distance of at least 70 cm from the surface of the earth to the top of the pipe. If the highway passes under a concrete platform or in places where vehicles are moving, the minimum recommended values \u200b\u200bfor the depth of the pipeline should be increased to 0.9-1 meters.

In addition, when arranging the external network, it is necessary to take into account the material of the pipes and the composition of the soil, since the depth of freezing different types  soil is not the same. Clay and loamy soils in the same area freeze less than fine sand and sandy loam. Coarse and gravelly sand have the highest level of freezing.

The table below shows how different the depth of freezing of different types of soil in the same city is.

Is it necessary to insulate the pipeline

The efficiency and longevity of the functioning of the external sewage system largely depends on properly performed insulation. This is especially important in the northern regions and when the pipes are laid above the freezing level. To understand how important insulation is, you need to imagine how the system works in the cold season.

During the passage of the liquid, which always has a positive temperature, the pipe is partially filled with liquid effluents. Water vapor also fills the pipe. In winter, at subzero temperatures, the part of the pipe that is closer to the surface cools, which leads to the formation of condensate, and then frost, which rushes to the center of the pipe, which often causes blockages.

The molded insulation is selected based on the diameter of the pipe, before laying the sewer line, it is simply worn on top

To avoid the formation of frost and blockages, as well as to protect the system from freezing, high-quality insulation of the pipeline allows. It can be performed using various materials that are currently available in abundance on the market: foamed polyethylene, polystyrene foam, isover, thermal insulation and others.

Heaters are roll and molded. The first are wound on a pipe during its laying in the basement. A similar application is in a heat-insulating shell made of foamed polyethylene.

They are not used as thermal insulation of underground lines. Basically, molded heaters are used, which are made for a specific pipe diameter. Thermal insulation material of the required diameter is simply worn over the sewer pipe.

One of the most popular heaters is Energoflex, which is made from extruded polystyrene foam. The closed structure of the material cells eliminates the penetration of groundwater, which can significantly reduce the insulating properties. Enhances foil cladding

If the temperature in the region is very low, then one insulation is unlikely to become reliable protection of pipes from freezing. In this case, a heating cable is usually used, which is laid on the outside of the pipe inside the heat-insulating material. When using a heating cable, you need to take care of the complete tightness of the joints so that moisture does not leak inside.

What is necessary to make a bias

When laying the pipeline, it is imperative to provide for a bias towards the septic tank. According to technological standards, the slope of the pipe with a diameter of 110 mm should be 20 mm for each meter of the pipeline. Pipes having a diameter of 160 mm must be laid with an inclination of 8 mm per meter of the laid line.

When laying pipes, the slope is calculated per meter of pipe. The figure shows how much the difference between the sides of pipes with different diameters should be

The presence of a slope is a determining parameter for the successful functioning of the system. The closer the pipeline indicators to the normative ones, the more efficient the sewage system will work. A complete lack of slope, as well as excessive slope of the pipeline, will lead to siltation of the system. In the first case, the waste will not be able to be transported through pipes at the required speed, which will lead to the formation of blockages.

In the second, the liquid will move too fast, which will ultimately reduce its transporting capacity, and waste will remain in the pipe, which will also lead to blockages and further siltation of the pipeline.

The slope of the pipeline should always be directed from the outlet from the apartment building towards the septic tank. This condition is especially important when using the non-pressure type sewers, which are often equipped with private households.

You can control the slope level of the entire trench using a special device - level. If the device is not on the farm, then the slope is checked using the building level.

1. At the beginning and at the end of the pit, pins are driven into which the cable is tied.
2. A building level is applied to one end of the rope and horizontal adjustment is made.
3. The height of the trench is measured on both sides to the cable.
4. Simple mathematical calculations are made.

For example, the total length of the trench is 50 meters, a pipe with a diameter of 110 mm is used. From the side of the exit from the house, the depth of the pit is half a meter. In this case, at the end point of the pit, its depth should be equal to one and a half meters.

If the site has a natural slope that exceeds the recommended standards, you can lay a sewer with several vertical passages. In this case, on horizontal sections of the pipeline it is necessary to comply with regulatory indicators.

In areas with a large slope, the pipeline can be laid in a stepwise manner. If the slope angle slightly exceeds the standards, they are limited to one vertical transition (+)

Another option is to lay a vertical pipe at a significant depth at the exit from the house, and already from it lay a pipeline with the desired slope. At the same time, the depth of the trench will be greater than when laying in the first way. For the same purpose, you can use a differential well, falling into which, waste water flows smoothly to a lower level of the pipeline.

Pipeline Works

Technologically, the process of laying sewage is not particularly difficult. First you need to dig a trench, the depth of which corresponds to the normative indicators specific to this region. Before laying sewer pipes, sand is poured into the bottom of the ditch. The height of the sandy base is 10-15 cm, so the depth of the trench should also be increased by these values.

Sand cushion allows you to align the bottom of the ditch. Sand must be carefully compacted before laying pipes to prevent subsequent shrinkage.

The width of the trench is laid about 40 cm more than the diameter of the pipe used. In the places where the pipes approach the septic tank and at the exit from the house sewerage, the trench is made a little wider so that it is convenient to carry out installation work.

To prevent the foundation and walls of the house from getting wet, the septic tank is installed at a distance of no closer than 5 m from the structure.

After the trench and the foundation are prepared, it is necessary to connect the pipes together, and then lay them. It is not possible for one person to lay long sections of the highway evenly and correctly, therefore it is advisable to involve several assistants in this work.

At the ends of the pipes are special sealing gum. Before they are docked with each other, a silicone plumbing lubricant is applied around the perimeter of the pipe, which facilitates the joining process and makes the joint more reliable. But here you can’t use force, excessive force on the pipe can damage the gum or tear it from its seat, which will lead to a violation of its tightness.

Before laying the prepared pipeline, a nozzle is put on the outlet from the house drainage, which has the required angle. The other edge of the line fits into the hole in the septic tank. If the storage well is made recently, it is advisable not to immediately close the hole with concrete, since the pipe may burst when the septic tank shrinks.

A pipe worn on the pipe leaving the house allows you to direct the pipeline in the right direction

Backfill of the sewer pipe is carried out as follows: first sand is poured so that the pipe is completely covered by it. Then it is poured with water, and after its shrinkage occurs, another batch of sand is added. After that, the highway is completely covered with earth.

According to technical standards, pivot wells must be installed in the places where the track turns, and observation pits are equipped for every 35 meters in straight sections of the pipeline. In addition, every 15 meters of the direct highway, an audit or cleaning is established.

Installation of the audit is a simple procedure, but it allows you to monitor the condition of the sewer network throughout the pipeline and, if necessary, clean the desired area with a cable or a stream of water

An audit can be done from the same sewer pipe, which is installed vertically in the desired sections of the pipeline using a tee. From above it is closed by a stub. With this fairly simple device, you can get quick access to a clogged section of the highway.

What to do when freezing sewers

If you have not insulated the sewer pipes, or insulated them insufficiently, and they have frozen, you first need to identify the damaged section of the pipeline in order to choose a method for solving the problem. Metal pipes can be heated using a blowtorch.

If the piping is made of plastic, open flames must not be used. You can pour hot water into the sewer, in which salt is previously dissolved (2 kg per 10 liters of water). You can direct a stream of steam or hot water in the revision closest to the frozen area.

If the damaged pipe is in the middle of the line, you can use a steam generator to warm the soil. However, this process can take quite a while. It is best to prevent freezing of the system, and when laying pipes to conduct their high-quality thermal insulation.

Useful video about laying a highway

In this video, the installation process of the external sewage system is described in great detail, as well as the normative indicators that must be followed during installation:

This video shows how to lay sewer pipes in the ground:

Despite the apparent simplicity, the work of laying sewer pipes requires a competent approach and knowledge of the regulatory rules for laying. Only with the observance of the necessary indicators and the correct performance of work, it is possible to equip a truly effective and durable sewer system.

To make a plastic sewer yourself is much easier than a plastic water pipe and much easier (physically) than to disassemble an old cast-iron sewer. The main thing is to follow a few simple rules outlined below.

Basic Rules:

These rules are formulated on the basis of the principle of operation of gravity (pressureless) sewage , and if any of the provisions below are not clear enough, then for clarification you can refer to the specified article.

1. The fewer joints and turns you make when laying pipes, the more reliable the system will work.

Each junction or turn is a potential place for leaking sewage during poor-quality joining and, in addition, additional resistance for liquid and especially for solid waste.

2. Sockets of vertical pipes (risers) and horizontal pipes should be directed towards the movement of wastewater.

This is done in order to minimize the risk of leaking sewage. Yes, and it is unlikely that you will be able to lay horizontal pipes in a different way. Sometimes, in case of repair of the sewer pipe, it is allowed to install couplings (sliding) couplings, in which one pipe (bell) is directed along the movement of wastewater, but it is generally advisable to avoid using couplings if you cut the pipe incorrectly, it is better to buy a new one.

3. Cutting and shortening of fittings (sockets) is prohibited. Not allowed for installation:

• all pipes, tubes and fittings having chips, cracks or cuts;
• shaped parts having an internal groove with sharp edges;
• rubber rings and cuffs with tears, sinks and unremoved extrusion, as well as rings in which there are no plastic spacers provided for by the design;
• metal fasteners, the elements of which have sharp edges and burrs at the joints with pipes and fittings.

Logically and without comment.

4. The diameter of the pipes depends on the number of connected sanitary devices and on the slope.

Of course, there are formulas that allow you to calculate the diameter of the pipe depending on the slope, the number of joints and turns, taking into account the number of sanitary appliances or, more simply, washbasins, bathtubs, sinks and toilets. But in practice, these formulas for intra-apartment wiring are rarely used, and there is no great need for this. And besides, the exact calculation of the required pipe diameter is the topic of more than one scientific dissertation.

To the riser and to the connection section of the riser to the well they put pipes with a diameter of 100 or 150 mm, and if you had a cast-iron pipe with a diameter of 200 mm (although this is very rare - pipes of this diameter are put on risers only if the number of connected sanitary devices is more than 1200, I do not think that this is your case, although everything is possible) , then a new plastic pipe must be installed with the same diameter. The exception is their home. There, the sewage was laid not from those pipes that are needed for technical specifications, and from those that managed to get it.

With internal horizontal wiring  usually put pipes with a diameter of 100 mm when connecting the toilet to the riser, all other pipes with a diameter of 50 mm (sometimes 40 mm).

If you some incredibly complicated wiring, and you doubt that a diameter of 50 mm will be enough for the normal operation of the sewage system, then you need a hydraulic calculation of pipelines. And to understand the intricacies of the movement of wastewater and waste through the sewer pipe, sometimes one higher technical education is not enough. If you still want to try it yourself, then take a look at SNiP 2.04.01.85, or get acquainted with the main provisions of the hydraulic calculation of sewer networks.

There you can find out the water flow rate and the number of drains from any sanitary device and, accordingly, the minimum diameter of the connected sewage system, and determine whether the main conditions are met: the flow velocity is at least 0.7 m / s and the filling of the pipe (the ratio of the height of the water to the diameter) is at least 0.3; what to do if these conditions are not respected, and many more interesting things that I try to summarize in this article.

5. Horizontal sewer pipes should be laid with a slope to the riser.

Since the sewage system is pressureless, and pressure losses due to air resistance and friction of the pipe walls occur, some pipe slope is required to maintain the flow rate. And so that the pipes are not silted up (sewage self-cleaning occurs), the flow velocity should be at least 0.7 m / s to ensure turbulent fluid flow, and the filling of the pipes should be h ≥ 0.3d. Like the diameter, the slope of the sewer pipes is determined by calculation. When the volume of wastewater is not enough to meet both conditions, the turbulence of the flow is put in the first place. When performing standard in-house wiring or the sewerage system of a small private house, the following requirements must be observed:

The minimum slope of the sewer pipe i \u003d 0.025 for pipes with a diameter of 50 mm, the recommended slope i \u003d 0.035

The minimum slope of the sewer pipe i \u003d 0.015 for pipes with a diameter of 100 mm, the recommended slope i \u003d 0.02

i is the ratio of the difference in height of the center of the diameter of the pipe to the length of the pipe. Translated into normal human language, this means that if you have a sewer pipe 1 meter long, then if the bottom of one of its sections touches the floor, then the bottom of the second should be 2 cm above the floor, of course, provided that the floor is horizontal and an increase in the diameter at the socket for the pipe joint is taken into account. In this case, the slope of the pipe is taken equal to the hydraulic slope of the fluid flow, thus ensuring a constant flow rate.

Maximum slope for horizontal sewer pipes i \u003d 0.15

With large slopes, the speed increases significantly, which in turn increases the force of water hammer and can lead to clogging of the pipe in areas with high local resistances (changes in the fluid path - turns of sewer pipes, connection point to the riser). Although such a restriction is conditional - it is unlikely that you will be able to lay a pipe 10 meters long with such a slope (outdoor work does not count). With a pipe length of less than 1.5 m, this restriction does not apply, since in such a relatively short section of the pipe, the wastewater will not have time to develop a high speed.

The floors may not be horizontal and determining the slope of the sewer pipe by floor level can lead to an error, the foundations of houses can sag, which is why the pipe slope may not change for the better. To avoid problems with the operation of the sewage system, it is advisable to make a slope of 4-7 cm per meter (for pipes with a diameter of 50 mm). The more turns and junctions on the sewer line (see p. 1), the greater the slope should be to compensate for local resistances.

If the pipes are laid without a slope or even with a counterclock, then such pipes will clog quite often. The correct solution to the problem is to eliminate counterclones or other causes of clogging of the sewage system, but this is not always possible, in such cases a check valve will help.

6. For normal operation of the sewer, pipes must be fixed to the floor or to the wall.

Plastic pipes, unlike cast-iron pipes, are easily deformed and long loose sections can sag, which will lead to a change in the slope. To prevent this from happening, the pipes must be fixed to the wall or floor with special fasteners (sold in the same place as the pipes) every 50-100 cm, depending on the diameter of the pipe. The fastening of the pipes of the riser to the walls is also necessary to reduce the load of its own weight. In addition, it is recommended to fix the pipes in the places of turns, connections for partial load perception from water hammer.

7. The presence of fan ventilation.

The ventilation pipe, which is led to the roof of the building or to the attic, is designed to equalize the air pressure in the drain pipes, which can drop sharply if a large amount of water is discharged along the riser, for example from the toilet. A sharp decrease in air pressure in the riser sucks water from siphons of plumbing fixtures, thereby destroying the water lock. And this leads to free access to the apartment of sewer gases with extremely unpleasant odors.

In addition, these gases can cause dangerous diseases. As a rule, in all houses with more than two floors, and often even in two-story buildings, there is fan ventilation. Moreover, if you, living on the top floor, want to remove the pipe leading to the roof during a redevelopment (and changing the riser route is a redevelopment), then no one will officially allow you this, and unofficially, there are options.

With a small amount of wastewater, the use of an unventilated sewer riser is allowed. Those. the riser is not displayed in the attic or on the roof. In this case, in the place of connecting the horizontal wiring to the riser (according to building codes and rules), it is necessary to “clean” and close it with a plug (so that the wastewater does not leak). And if, in addition to cleaning, you also make a vertical outlet for a check valve valued at $ 4-10:

(Of course, if you wish, you can buy a branded valve for $ 100), then in the future save time, money and nerves needed to clean the sewer.

If for some reason you don’t have the opportunity to put a non-return valve directly on the riser (this sometimes happens when repairing sewers in your homes), then a non-return valve with a diameter of 50 mm can be installed on any part of the horizontal pipe, but it is desirable that the valve is located on 30-50 cm from the axis of the sewer pipe. Options for installing a non-return air valve can be as follows:

Option A is the most correct. Option B is valid in their homes, for example, in the country house, I installed a non-return valve according to option B four years ago. Option C is also permissible in their homes when it is not possible to put a non-return valve on the riser, for example, I put a sister who lived in my house about 5 years ago, a 50 mm diameter non-return valve, according to option C, I placed the tap for the non-return valve under the bathtub (the fact is that other people did the sewer to the sister and did not provide ventilation, and then it was easiest to insert a tap for the air valve under the bathtub). On the diagrams, taps for cleaning are not shown.

The essence of the air check valve is that it passes air only in one direction - into the sewer, when water in the toilet is flushed, then the air pressure in the sewer pipe in the section up to the toilet and in the riser (if any) opens and the valve opens. When the air pressure in the sewer pipe is the same as in the room and greater than in the room, the air valve is closed - this prevents the escape of gases from the sewer, so that when properly installed, there should be no odors in the room where the air valve is installed.

It does not make sense to put the air valve on the sewer pipes after the toilet, in which case the valve will not work correctly. When water flows down the toilet, and the toilet is a plumbing fixture that creates the maximum flow of wastewater, then the air pressure in the sewer pipe after the toilet will be increased. The higher the non-return air valve from the axis of the sewer pipe, the lower the risk of clogging of the valve sewage  with clogged sewers, so option A is the most correct.

8. It is necessary to install “cleaning” in places of turns, changes in the angle of inclination and the connection of the sanitary device to the sewer pipe.

A good rule, but it has been observed for a long time, when installing a cast-iron sewer. In old houses you can still see somewhere under the sink the appendix of a sewer pipe with a wooden chop sticking out of it for a good 20 cm. Now plumbers involved in the installation of plastic sewage systems do not install a “clean-up” (I at least have not met) for several reasons.

First, sewer pipes are often sewn up for aesthetic reasons. Secondly, modern plastic sewage, unlike cast-iron, is quite easy to disassemble and, if necessary, you can always disconnect some sanitary appliance, for example, a washing machine or sink, and introduce a cable through the hole to clean it.

9. The audit (inspection hatch) should be installed in no more than 15 m.

In five-story houses, revisions were installed on the first and last floors. If on your sewer riser at a height of about 1 m from the floor there is some kind of iron plate screwed with powerful bolts and causing unpleasant associations with kingston, then this is a revision. Revision for plastic sewers looks much more aesthetically pleasing:

If you are going to sew up the riser, then make an inspection hatch to access the revision.

10. Plastic sewer pipes can be joined with cast-iron.

If you have a cast-iron riser, it is not necessary to change the cast-iron pipes to plastic ones if the riser is in good condition. In addition to considerable physical effort, you will also need a lot of moral effort to convince your neighbors not to use the sewers for several hours and, as usual, someone will forget. But even if you completely change the cast-iron riser to plastic only in your apartment, you still have to join the plastic and cast-iron pipes.

11. When the riser goes into a horizontal pipeline, it is forbidden to use a 90 ° branch.

A good rule, the observance of which can reduce the force of water hammer, the turbulence of the liquid waste stream and thereby avoid frequent clogging of the sewer. If your sewer is often clogged up in your high-rise building, go down to the basement and check if the builders violated this rule when installing the sewer.

And if you have your own home and 5-6 sanitary devices are connected to the sewage system, then you can ignore this rule.

12. It is allowed to lay plastic pipes in the ground in the absence of additional external loads.

13. Viewing wells are arranged at a distance of not more than 50 m, as well as in places of turns, changes in the angle of inclination and elevation of the pipeline.

The first viewing well is arranged at a distance of no more than 8 m from the axis of the riser - with a discharge diameter of 50 mm, 12 m - with a discharge diameter of 100 mm, 15 m - with a discharge diameter of 150 mm or more. In general, the latter two rules are relevant for owners of private houses involved in the laying of sewers. Usually these are quick-witted people and they do not need additional comments. But just in case, I will give a link to an article that briefly describes the construction of sewer wells.

1. Sometimes rubber seals (gaskets) are sold separately from pipes and may not provide a tight fit of pipes during installation.

When buying pipes and gaskets, insert one gasket into the socket and try to fit two plastic pipes. If one pipe is quite easily inserted into the socket of another, it is advisable to immediately change the gaskets or look for another seller.

Since a high-quality pipe must fit very tightly into the socket of another pipe, the use of shampoo or liquid soap (they are usually always on hand) greatly facilitates the docking process.

3. When joining pipes, one pipe enters the socket of another by 47 and 36 mm with a diameter of pipes and fittings of 100 and 50 mm, respectively.

4. When installing plastic sewers, standard-length pipes are used.

But the apartment’s design does not change due to the modular dimensions of the pipes, and the modular pitch is not very happy: 150 mm, 250 mm, 500 mm, 1000 mm, 2000 mm, 3000 mm. If you need a pipe of a different size, then you can always cut it smoothly and accurately, as a result you will get a pipe cut sometimes better than the factory one.