Diameter and dimensions of PVC sewer pipes. Sewage pipes diameters External sewerage pipes diameter

Sewage pipes diameter 50 and 110mm

In the process of building a new house or major renovation of an existing building, the question arises of choosing materials for the wastewater disposal system. Among other parameters, it is necessary to determine the diameter of the sewer pipes. It must ensure the normal functioning of the circuit. It is generally accepted to install lines with a diameter of 100 mm in toilet rooms, and 50 mm in kitchens and bathrooms.

Size justification

The twofold difference in size is due to the fact that the toilet needs to provide a large flow of water in a short period of time. In addition, waste from this particular room can block the circulation of wastewater through pipes of small cross-section.

A natural observation may arise that much more water is drained from the bathtub into the central sewer.

This is true. However, installing a larger diameter pipe is inappropriate here. After all, all plumbing equipment is equipped with small outlets. They are not capable of providing a full load for a 100 mm main line. Therefore, it is irrational to clutter the room with large pipes.

There is also no point in looking for a pipe with a diameter of 200 mm if a bidet is installed in the toilet room in addition to the toilet:

• Firstly, because the simultaneous use of these two nodes is unthinkable. And to reboot the line, a long and continuous operation of both the toilet and the bidet is necessary.
• Secondly, the throughput of the pipe is proportional to the square of the cross-section. In other words, it will drain wastewater from two nodes just as effectively as from one.

The required diameters of sewer pipes for different rooms are indicated in SNiP. They are selected in such a way as to not only guarantee timely drainage of wastewater. Their dimensions are adjusted and take into account the need for free space for air movement. After all, without this, in apartment buildings, water from the ninth floor will displace air from the sewer into the apartments located below. It's unlikely that anyone will like this.

Determination of the diameter of sewer pipes

Many regulatory documents describe methods for calculating the linear parameters of sewer pipes. They are complex because they take into account many factors: intensity of use, length of horizontal sections, angle of inclination, etc.

It is not advisable to use them to organize an allotment on the scale of one apartment or private house. Another thing is practical experience. And he allows us to say that:

1. For any city apartment or country house with a moderate number of sanitary rooms, a pipe measuring 100 millimeters is sufficient.
2. For bathrooms, kitchens, urinals and bidets, lines half the size are suitable.
3. The inside diameter of cast iron systems decreases over time due to deposits.
4. In apartment buildings, risers measuring the same 100 millimeters are installed. The exception is high-rise buildings (over 5), where 150 mm systems are installed.
5. Horizontal sections of a multi-storey building scheme that are connected to several risers may be larger in size. As a rule, it is 200 mm.
6. Plastic pipes, if the angles of inclination in horizontal sections are observed, are practically not overgrown with deposits.

From the above facts it follows that the diameter of plastic sewer pipes for the same area may be smaller than for metal analogues.

It’s not surprising to find unusual sizes on the modern market. The cross-section of polymer products can be, for example, 75.9 mm. Don't get carried away with purchasing them. The fact is that it is not always possible to select fittings and adapters for such models. But making joints only with cement or sealing materials is risky. Sooner or later, such connections will inevitably leak.

General installation rules

Installation of sewer pipes

It is necessary to firmly understand that horizontal connections can only be installed using tees. Right angles are allowed only at the points where the system is connected to the central riser. Subsequently, following this rule will help you painlessly clean your home sewer.

There are several more established axioms of installation:

• A horizontally laid pipe should be smaller in size than the riser into which the waste drains.
• There should be revisions at turning points. These are holes covered with a lid that allow you to clear the area of ​​possible blockage. Their installation is not necessary near siphons, connection tees and other elements that can be removed. In three-story (or more) buildings, the vertical riser must have at least 2 inspection points. As a rule, in city houses these elements are installed every 3 floors. In horizontal sections of 12 meters or more, installation of an inspection is also necessary.
• Under no circumstances should you plug the sewer riser at the top. This will lead to the spread of unpleasant odors throughout the floors of the house or cottage.
• The horizontal lines of the circuit should be laid with a slope, regardless of the type and diameter of the pipes used. A 1 centimeter reduction in height is sufficient per linear meter of the system. In ideally installed systems this figure is 2 centimeters. But you shouldn’t get too carried away - too much bevel provokes the sound of water during release.
• Sewer pipes are fastened every 10 sizes of its diameter.

The formation of counterslopes is unacceptable. The sockets must be directed against the flow of water.

Plastic systems require special attention. The fact is that they are most susceptible to thermal expansion. Therefore, during installation there is no need to insert the pipes end-to-end. A little free space (2-3 mm) and they will “play” when heated. In this case, the tightness of the system will not be affected if all sealing elements are installed.

One of the most important parameters that you should pay attention to when selecting pipes for a sewerage system is, in addition to the pipe material, the diameter of the sewer pipe, because for different internal sewerage systems, pipes of different diameters are used. All sewer pipes are manufactured strictly in accordance with the Technical Specifications. At the same time, manufacturers offer a huge selection of products in different sizes. Therefore, it is easy to choose exactly what is required for each specific case. The article below will tell you how to do this.

The influence of diameter on other pipe parameters

As we have already said, one of the main parameters of any pipe is its diameter. He defines the scope of its application:

1. to drain water from a free-standing bathtub or sink, use pipes with a diameter of no more than 75 mm;
2. pipes draining wastewater from the toilet should already have a diameter of 100-110 mm;
3. Large-diameter sewer pipes are used to drain all collected sewage outside the building.

The diameter of the sewer pipes determines their other parameters:

• Pipe wall thickness. Large diameter pipes (up to 160 mm) have larger wall thicknesses than pipes with a diameter of up to 110 mm. They are 3.9 and 3 mm, respectively.
• Pipe weight. 1 m of pipe with a diameter of 160 mm weighs about 2 kg, while a pipe with a diameter of 110 mm of the same length weighs just over 1 kg.

Inner and outer diameter

Typically, factory markings indicate only the outer diameter of the sewer pipe and its thickness.

Pro tip: In order to determine the internal diameter of the purchased pipe, it is necessary to subtract twice its thickness from the external diameter.

It is necessary to know the internal diameter of the sewer pipe so as not to make a mistake in selecting pipes to perform certain tasks in the sewer system being installed.

There is an approximate gradation of pipes used in certain cases for internal and external sewerage:

• Pipes with a diameter of 25 mm are used to drain water from the washing machine or dishwasher.
• Pipes with a diameter of 32 mm are suitable for drainage from the shower cabin, bathtub, and sinks.
• The general sewerage distribution in the apartment consists of pipes with a diameter of up to 40-50 mm.
• To drain all wastewater outside, pipes of the largest diameter are used - from 160 to 200 mm.

Pipes made from different materials are usually used for different types of sewerage. Thus, for the installation of external sewerage, plastic pipes are often used, for example, PVC sewer pipes: their diameter is most often 110 mm.

Cast iron pipes have markings that indicate their nominal (actual) diameter. For example, the designation “DN 100” indicates that the diameter of the “nominal bore” of the pipe is 100 mm. Thus, to determine the nominal internal diameter of cast iron sewer pipes, it is enough to check their markings.

Smallest permissible diameters

According to Sanitary Norms and Rules (SNiP), for various types of sewerage networks, pipes can be used, the minimum size of which is:

• for the drainage of industrial and domestic waters inside the block - 150 mm;
• for the same street networks – 200 mm;
• for a quarterly network that drains rainwater - 220 mm;
• for street stormwater network – 250 mm;
• for networks that discharge sludge under pressure - 150 mm.

In some cases, minimum pipe sizes are allowed:

• for settlements where the volume of wastewater does not exceed 300 cubic meters per day, both for street and neighborhood networks that discharge industrial waters, it is possible to use pipes with a minimum diameter of 150 mm;
• For some production networks, if justified, this diameter may be even smaller.

Determining the exact pipe diameter

Convert mm to inches

It is sometimes not very easy to determine the diameter of the required pipe, since it is often indicated not in millimeters, but in inches. To move from one unit to another, there are various tables that you can use.

The conversion table shown in the figure above is used if it is possible to measure the diameter (the pipe is not fixed) with a ruler or using a caliper.

Pro tip:

To measure the diameter of an existing (installed) pipe at home, you just need to attach a ruler to it and measure its “thickness”. If the resulting number is about 32 mm, then the fitting diameter of the pipe is 1 inch; about 28 mm is already ¾ inch; 16 mm - ½ inch.

Calculation of the required pipe diameter

It is important to know the diameter of the pipes used in the installation of the system. The volume of liquid carrier passing through the pipes is directly related to their diameter. You can make an accurate calculation of the diameter of sewer pipes yourself.

The diameter is calculated using a simple formula:

Where:

• V is the speed of movement of liquid masses through pipes. The indicator should not exceed 0.7 /s. You can select it from the table below.

• h/d – pipeline fullness indicator. It is the ratio of the flow height h (maximum) to the internal diameter of the pipe. The minimum value should exceed 0.3, the maximum should not exceed 0.6.
• K – coefficient depending on the pipeline material. So, for polymer products it is 0.5, for other materials – 0.6.

The most optimal sewer system option is easy to create if you adhere to the calculated pipe diameter. Drawing up a preliminary detailed design of the entire sewerage system in the house will allow you to determine the required number and size of pipes purchased for installation of the system.

The history of sewerage goes back more than one century. The remains of ancient hydraulic structures were discovered by archaeologists in Egypt, Greece, China, and Italy. Most sewers were made of stone in the form of a gutter that ran right along the city streets.

Later, the system of drains (gutters) was hidden underground, and the first sewers began to be made from copper sheets. With the growth of industrial production, sewer pipes and components appeared, which became the prototypes of modern systems.

The diameter of the sewer pipe depends, first of all, on where it will be installed. If we do not take into account the networks and collectors that receive all wastewater from industrial and residential facilities, then the diameter of the sewer pipes of internal networks usually does not exceed 50 – 110 mm, for external highway from 110 to 600 mm.

Important! Since the diameter of the sewer branch directly depends on the volume of wastewater, before installing the system you should take into account the number of plumbing fixtures and the throughput of the future pipeline.

Most internal networks are made from pipes with a diameter of 110 mm.

These are central risers and pipes through which sewage water is discharged to the outside of the system. Showers, washbasins, washing machines and other equipment are connected to taps with a diameter from 32 to 50 mm.

External sewerage is carried out with pipes of different sizes. The diameter of a pipe for a private house or small facility usually does not exceed 110 mm.

If this is an apartment building, then for high-quality drainage of sewage to the central collectors, pipes of a larger cross-section, from 160 mm or more, are used.

Outside diameter

When installing both internal and external pipe diameters, the outer diameter is of great importance.

In technical documents this value is indicated by letters Dн– outer diameter (nominal). Since many systems are installed in previously constructed mains, the value of the outer diameter is a matter of paramount importance.

It all depends on the material of manufacture, because in the recent past most sewerage systems were built only from cast iron and asbestos-cement pipes. Currently, products made from polymer materials are more often used.

Markings on plastic products indicate the outer diameter, while cast iron and steel counterparts indicate the inner diameter.

It is not recommended to install sewerage systems from different types of pipes, which is due not only to the difference in diameters, but also to the different physical properties of the products.

Inner diameter

dvn– designation of the internal diameter of the sewer pipe. This parameter can differ significantly even for pipes with the same outer diameter. This is due primarily to the wall thickness.

Typically, such pipes are used to install pressure sewer systems and pipelines, which in the future will be subject to serious ground loads.

You can find out the internal diameter using a simple formula:

din = Dn – 2b,

Where Dн– outer diameter of the pipe; b– wall thickness.

Pipes with a small internal diameter ( up to 100 mm) are used for wiring internal sewerage systems, and pipes whose internal diameter exceeds 160 mm, usually used when laying external highways.

Calculation

At the initial stage of carrying out internal and external sewerage, it is necessary to correctly mark the drainage points for plumbing fixtures.

Depending on the number of connection points, the diameter of the main riser and sewer outlets is calculated.

In this case, all turns and butt joints along the entire length of the pipeline must be taken into account.

The calculations take into account the physical state of the inner surface of the pipes, the coefficient of friction resistance, the speed of movement of wastewater and other indicators.

But all calculations are made only if necessary, and for this it is enough to know what diameter the central sewer riser should have, and what diameter the plumbing outlets will have.

Plastic pipes

When laying sewer systems, plastic pipes are increasingly being used as an alternative to bulky cast iron counterparts. In addition, plastic products have a number of advantages, are produced in various designs and are easy to install.

For the internal sewerage network, pipes with a diameter of 110, 50 and 32 mm. Different types of shaped parts simplify their connection, and rubber gaskets in the sockets prevent the possibility of leakage.

For external networks, plastic pipes with a diameter of 110 mm and more. Joining of such pipes is possible both by the socket method and by soldering. In this case, they apply.

Plastic pipes have good throughput and have physical properties that enable sewer pipelines to serve for a long time without serious accidents.

PVC

Today, almost all sewer pipelines are made of PVC pipes. The wear resistance of pipes, their capacity, and durability have made pipes made of polyvinyl chloride almost indispensable for the installation of any sewerage system.

The industry produces pipes not only of the most common diameters 110, 50 and 32 mm, but also larger in size.

It all depends on the type of rigidity of the pipes and their purpose. When installing external sewerage, pipes are used from 110 to 500 mm, in addition, the wall thickness can reach up to 15 mm!

Naturally, such pipes are not laid in yard sewers, but are used in main pipelines collecting city-wide wastewater.

Cast iron

Despite the fact that many sewer systems use plastic pipes, cast iron products have not gone by the wayside. Although their use in internal sewerage is very rare, they are still indispensable in domestic and urban sewer lines.

Cast iron pipes are produced by centrifugal casting, with sockets for connections. Modern analogues have good anti-corrosion protection and have an internal coating to reduce friction.

The socket joint is sealed not by stamping, but by means of an O-ring or a special cuff. “Natural” sound insulation of metal does not require additional costs for sound-absorbing materials.

They produce cast iron pipes of standard diameters. For internal and external sewer distribution, products with an internal diameter are most often used from 50 to 300 mm. This is the so-called medium size.

Large diameter sewer pipes – from 300 to 1200 mm used in urban and large sewer lines.

Important! The diameter can be determined by the markings. For example, “DN 50” means that the internal bore diameter of the pipe is equal to 50 mm.

How to choose

The choice of sewer pipes is made based on the amount of expected drainage. In most cases, the main line is installed from pipes with a diameter of 110 mm. For domestic wastewater this is the best option.

In addition, ease of installation and the presence of various shaped parts makes it possible to connect pipes of various diameters to the central drain.

For many plumbing fixtures, an outlet with a diameter of 32 mm, others have a water seal system under 50 mm pipe.

But the main thing that should be taken into account when laying intra-house sewerage is the possibility of unhindered drainage of wastewater from household plumbing fixtures.

The technical documentation supplied with most household appliances indicates the minimum diameter of the sewer outlet to which the connection is made.

It follows from this that the diameter of the sewer pipes in the apartment must be selected based on the technical characteristics of household units and plumbing fixtures.

For the sink

Based on the fact that all fittings included with the washbasin are designed for connection to sewer pipes with a diameter of 40-50 mm, installing a branch with a larger cross-section is impractical.

Pipe diameter in 50 mm has sufficient throughput, which contributes to good and unhindered drainage of water from the sink.

For toilet

The toilet is practically the only plumbing fixture that requires a mandatory connection to a pipe with a bore diameter 100 mm.

In this case, the length of the outlet pipe should be as short as possible, i.e. the distance to the central riser is kept to a minimum.

The connection of the toilet bowl to the outlet pipe is made through a special corrugation, one end of which is placed on the outlet neck of the toilet, and the other is inserted into the outlet pipe.

Thanks to special cuffs on the corrugation, leakage and the appearance of unpleasant odors are completely eliminated.

For bathroom

Although a large volume of water is drained from the bathtub, the diameter of the outlet pipe usually does not exceed 50 mm. This is due to the fact that the smaller the hole, the smaller the volume of liquid will flow out of the bath over a certain period of time.

Since the hole diameter is smaller than 50 mm, and there is a special grate that does not allow water to pour out in a continuous stream, then there is no need to worry about the capacity of the sewer pipe.

For washing machine

must be produced in accordance with the established standards of the manufacturer.

The diameter of the drain hose of the washing unit is 32 mm, which means that the neck of the outlet pipe must be no less than this value.

But since when installing internal sewerage, in most cases pipes with a flow section are used 50 mm, then a rubber cuff is used for a tight connection 50x32 mm.

The drain hole for the washing machine must be at least 50 cm from the base of the floor.

If it is not possible to connect to the above, make an additional outlet from pipes with a diameter 32 mm. The entire structure is fixed to the wall with clamps.

If the washing unit is installed near a sink, then it is possible to connect the drain hose to a special outlet in the siphon design.

Important! In this case, all parts of the siphon should be carefully sealed, since water from the washing machine is supplied under pressure, and leaks are possible.

For kitchen

The kitchen is that room in the house in which several drain points can be located on one pipe. Sink, washing machine and dishwasher are the most common plumbing fixtures in this room.

If a drain outlet is quite suitable for washing 50 mm, for a washing machine – 32 mm, then for a dishwasher it should not be less than 40 mm.

It makes no sense to make a separate sewer hose for each. One pipe with a diameter of 50 mm with bends is laid, and if the drain hose of the device is smaller than the opening of the socket, then special rubber cuffs are used.

For shower cabin

Unlike a bathtub, a shower stall does not drain such a large volume of water. Water removal occurs in proportion to the amount of liquid supplied to the watering can.

In addition, the hole in the tray is no larger than the hole in the bathroom.

The set with siphon and drain hose may vary for different models of shower cabins, but usually varies within 32-50 mm. This means that to drain the used liquid, it is enough to lay a pipe with a diameter of 50 mm.

Table

This table shows the diameters of the pipes used to drain sewage from plumbing fixtures:

Important! If it is impossible to connect plumbing due to a mismatch in the diameters of the hose and pipe, rubber adapter sleeves are used.

With such a large selection, finding sewer pipes of the required diameter is no longer particularly difficult, which makes it possible to carry out high-quality and efficient sewerage in a short time, without significant financial and physical costs.

Which can be used when installing drainage networks in a suburban area.

As you now know, wastewater can be released using a filtration well, a septic tank, or local treatment facilities. But this is not enough to build a sewer system.

You need to know which pipes are preferable to use for installing a sewer network. To do this, you need to answer the following questions: “How to choose the material and diameter of the pipes? What is better to use – HDPE polyethylene, polypropylene or high-density pipes?”

In this article, let's look at how one material differs from another and what the choice of diameter depends on.

Sewage pipe material

Today, various materials are used in construction, including when laying utility networks, which include sewerage networks.

Depending on the purpose and operating conditions, sewer pipes made of the following materials are used:

• ceramic;
• concrete;
• asbestos-cement;
• cast iron;
• polymer (PP, PVC, UPVC, etc.).

All sewage drains can be divided into household wastewater (fecal sewerage) and surface runoff of melt and rainwater. Depending on the purpose of the sewer network, the conditions for its installation, the diameter and material of the pipes are selected.

Read on to find out which pipes are best to choose in which case.

Pipes for internal sewerage

Internal sewerage is laid inside buildings and is intended to drain wastewater from plumbing fixtures to the external network outside the building.

The wastewater flow rate is determined according to SP 30.13330.2012 “Internal water supply and sewerage of buildings” (updated edition of SNiP 2.04.01-85*).

The calculation uses data on the number of plumbing fixtures, the second flow rates of wastewater from these fixtures, as well as the probability of their simultaneous use in order to ensure the free passage of the maximum possible flow rates by sewer pipes.

This takes into account the climatic region and the degree of improvement of the building.

To check the diameters obtained by calculation, you should use tables of the throughput of ventilated and non-ventilated risers made of polymer materials and cast iron pipes (Tables 6-12 SP 30.13330.2012) depending on the height of the riser and the angle of connection of floor branches.

This kind of calculations is quite complex and is used in the design of multi-apartment residential buildings and industrial enterprises.

To select pipe diameters in a country private house or bathhouse, you can use a simpler method - tables of standards for drainage from plumbing fixtures based on equivalent costs. In this case, the second flow rate (l/s) from the sink is taken as 1 equivalent, equal to approximately 0.33 l/s.

Based on the table, pipeline diameters are accepted depending on the amount of installed plumbing equipment.

What such a table looks like is shown in the figure below (click to enlarge):

As you can see, the largest diameter (100 mm) is required to connect the toilet. To connect sinks, sinks and washbasins to the sewer system, pipes with a diameter of 40-50 mm are sufficient.

The following materials are used for laying internal sewerage:

• Polyethylene;
• Polypropylene;
• Polyvinyl chloride;
• Polybutene;
• Cross-linked polyethylene;
• Fiberglass.

As a rule, pipes for internal sewerage are gray in color, by which they can be distinguished from pipes for external installation, which are orange.

Let's look at the features of different materials below.

PVC and uPVC sewer pipes

Pipes made of polyvinyl chloride and uPVC (non-plasticized polyvinyl chloride) are widely used in sewer construction due to the following advantages:

• light weight;
• low cost of manufacturing and transportation;
• ease of machining;
• ease of installation of PVC pipelines.

But they also have disadvantages. These include:

• deformation under the influence of elevated temperatures;
• poor resistance to some chemically active substances in sewage;
• flammability with the release of toxic substances during combustion.

HDPE pipes

The abbreviation HDPE means low-density polyethylene, which characterizes the manufacturing method of this material, popular in modern drainage systems. HDPE pipes are produced in accordance with GOST 22689.2-89 “Polyethylene sewer pipes and fittings for them.”

Notable advantages of polyethylene pipes include:

• high tensile strength;
• increased rigidity;
• temperature range from -50 to 130 degrees;
• high smoothness of the inner walls of the pipe;
• long service life;
• ease of transportation and installation.

The disadvantages include slightly lower resistance to direct exposure to ultraviolet rays than pipes made from other materials.

Polypropylene pipes

Polypropylene pipes are characterized by the best resistance to elevated temperatures and, thanks to this, can even be used in heating systems.

In addition, polypropylene has other advantages - plasticity, resistance to mechanical damage, ease of assembly and high durability of sewer networks made from this material.

Requirements for internal sewerage

When laying internal sewerage, the requirements of SP 30.13330.2012 “Internal water supply and sewerage of buildings” should be taken into account regarding the connection of pipeline fittings and the installation of indentations.

For example, it is recommended to connect sanitary fixtures to risers using oblique crosses and tees.

As a pipe material for internal installation, it is recommended to use pipes made of modern polymer materials that have a guaranteed service life of at least 25 years without changing their physical and chemical characteristics.

The sewer riser is installed at least 20 cm above a pitched or flat unused roof and has a distance from openable windows, vents and balconies of at least 4 meters.

Requirements for internal drains

If you are building a house in which the project involves the installation of internal drains, then you should know the requirements that apply to them:

1. Internal drains can be installed from polyethylene and metal pipes.
2. The estimated flow of rainwater and the number of drains are determined according to the climatic characteristics of the design area and depend on the intensity of rain in the area.
3. Gutters are designed to handle the hydrostatic pressure that can occur if a blockage occurs. Also, when installing fasteners, it is necessary to take into account the weight of the drain filled with water.
4. The passage of internal drains through residential premises is not permitted.
5. Inspections on drains should be installed on the first floors of buildings before release.

Pipes for external sewerage

External sewerage performs the function of draining wastewater to treatment facilities or filtration wells.

Based on the material of external sewer pipes, there are:

• Cast iron;
• Concrete;
• Asbestos-cement;
• Polymer.

Cast iron pipes

Not so long ago, cast iron pipes were the most popular choice for installing both internal and external sewerage networks.

Cast iron has excellent physical and chemical properties, which ensure its popularity today. And, if cast iron can be found in internal sewerage systems today in houses built several decades ago, then cast iron is still used as pipes for external installation today.

The obvious advantages of cast iron pipes include the following qualities:

• do not rust;
• have high strength, which allows them to be laid in the ground without fear that the pipes will deform under the influence of the weight of the soil or loads from passing vehicles;
• Cast iron pipes are very durable and have a service life of up to 80 years.

But they also have disadvantages. The main disadvantages are:

• heavy weight, making transportation and installation difficult;
• increased fragility - the pipe can be split by hitting it with a hammer or carelessly hitting it against a stone;
• the inner surface of cast iron pipes is not as smooth as that of polymer pipes, and various contaminants gradually accumulate on it, which leads to a narrowing of the bore diameter of the pipes and the appearance of blockages;
• significant cost compared to plastic pipes.

Ceramic pipes

During the economic feasibility study, pipes made of ceramics are used in external sewerage networks, manufactured in accordance with GOST 286-82 “Ceramic sewer pipes”.

Ceramic pipelines have high strength to physical stress, are resistant to the chemical composition of wastewater and have a significant service life.

The disadvantages include fragility and labor-intensive installation. For product diameters up to 600 mm long, ceramic pipes are manufactured in lengths of only up to 1500 mm.

A very popular choice for installing small-diameter sewer outlets is asbestos-cement pipes in accordance with GOST 1839-80 “Asbestos-cement pipes and couplings for non-pressure pipelines.”

They are easy to install, weigh less than ceramic or cast iron pipes, are also resistant to aggressive chemical environments and have good wall smoothness, which reduces the likelihood of blockages.

Asbestos-cement pipelines are assembled using couplings.

Modern polypropylene or polyethylene pipes can also be used for laying external sewer networks.

They can be distinguished from pipes for internal installation by characteristic stiffening ribs, thanks to which the pipe looks like corrugation. Double walls and ring reinforcements give such pipes strength sufficient to support the weight of the soil when laid at a standard depth.

Plastic pipes are much easier to install than cast iron, ceramic or asbestos-cement pipes.

The video below shows the installation of plastic corrugated polypropylene pipes.

When developing a sewerage system for a new house or during its major renovation, the most important stage is the selection of materials, at which the calculation of the main parameters takes place, which, in turn, is used to select the diameter of the sewer pipe.

The main parameters when designing a sewer system, in addition to the diameter, are the following:

• slope, which ensures normal operation of wastewater drainage;
• turns: their number, angle of rotation;
• methods by which pipes are connected to each other, to fittings and plumbing fixtures.

Features of choosing the diameter of waste pipes

The question of what diameter of sewer pipes should be selected is one of the first when designing. Typically, pipes with a diameter of more than 100 millimeters are suitable for toilet drains, and up to 50 mm in the kitchen and bathroom.

The diameters of sewer pipes have a wide range of values ​​due to two factors:

1. The toilet is a plumbing fixture, the features of which include the passage of a very large volume of water in a short period of time at the time of flushing.
   It may contain solid fractions, with which a pipe with a smaller diameter is more likely to clog.
2. Despite the fact that when the bath is emptied a lot of water is also drained, the drainage pipes are made of a much smaller diameter.
   This is due to the fact that, according to hydraulic conditions, the permeability of the pipe is equal to the permeability provided by its narrowest point.
   And in the bathroom the outlet has a disproportionately smaller diameter, in addition, it is blocked by a grill. This makes it impractical to install a large diameter pipe in relation to the bathtub.

Pipe diameter for series-connected plumbing fixtures

What to do if in the toilet room there is a bidet in addition to the toilet? In this case, the diameter of the sewer pipe should not be increased to 150 or 200 mm. This is explained by the following formula: the permeability of a pipe depends on the square of its diameter.

That is, if we take a two-hundred-millimeter pipe, we find that its permeability is four times greater than a pipe with a diameter of one hundred millimeters. In addition, it is almost impossible for the toilet and bidet tank to be filled to the maximum.

In other words, the diameters of sewer pipes - toilet pipes are taken larger not because a smaller diameter will not allow the required volume of water to pass through.

It should be noted that in order to pass the required volume of wastewater, including solid fractions, the pipe must have an air gap. This is important because as the water front moves through the drain pipe, air is displaced and is under high pressure.

The vacuum formed in the absence of an air gap in the pipe can squeeze out the water seals in all outlets, thereby causing a lot of troubles, from the appearance of an unpleasant odor in the room to the need to wash plumbing fixtures.

Standards regulating the diameters of sewer pipes

Any structurally required diameter of sewer pipes is regulated by SNiP 2.04.01085. There are methods for calculating all the main parameters of such pipes. The calculations there are not simple; they involve taking into account a variety of factors, for example, the slope of horizontal sections, the angle at which the outlets from the apartments are connected to the riser, and many others.

The tables, which are presented in this SNiP for clarity, contain data that allows one to calculate the maximum permeability of a pipe with a clearly fixed diameter, in other words, to solve the inverse problem.

But most often we need a solution that is clear, simple and gives accurate values ​​for all the main characteristics.

And the solution is this:

1. A pipe with a diameter of one hundred millimeters will be quite enough to organize a sewer system in any house or apartment, when the number of plumbing fixtures is within reason.
2. A fifty-millimeter sewer pipe is suitable for washbasins, bidets, bathtubs and urinals: this diameter is sufficient for flushing plumbing fixtures.

It must be remembered that the internal diameter of cast iron sewer pipes decreases over time due to the fact that they become silted.

1. In multi-storey buildings, if there are five floors, the risers are made with a diameter of one hundred millimeters, if there are more floors - 150 mm.
2. The areas of the drainage system that are common to several risers, as well as the exit to the well, are made with a diameter of 200 millimeters.

Plastic sewer pipes do not change their internal diameters, unlike cast iron ones. Due to the fact that their surface is smooth, fat deposits do not form on it. If the correct slope of the pipe is organized and there are no unevenness or roughness inside it, then there will be no deposits of sand and silt either.

It is this phenomenon that makes it possible to install different diameters of pipes made of cast iron or plastic: the diameter of a plastic pipe can be chosen smaller than a cast iron one, for example, a cast iron “fifty” can be replaced with a forty-millimeter plastic pipe.

How to select the diameter and other parameters of the drain system

There are some nuances that a sewer pipe requires to take into account when organizing a drainage system: the diameter of the horizontal pipe with the riser should not be larger than the riser itself. Any narrowing of the flow is a place where there is an increased risk of clogging.

All connections of a horizontal location should be mounted with oblique tees.

Using a rectangular connection, it is possible to join the riser and the horizontal section.

Thanks to this, there are no problems when cleaning pipes.

Features of the installation of a domestic sewer pipeline:

• At all joints and changes in flow direction, special cleaning holes with covers are installed - inspections. In multi-storey buildings, revisions are installed across three floors.
  If there is a straight long section, an inspection must be installed there too.

• The sewer channel is left open at the top to allow air to leak in. This will prevent the suction of the water seal when flushing on the lower floors.
• The slope is made within two centimeters. This is the most optimal size, since a larger slope will ensure rapid silting and noise of water when draining, and with a smaller slope the water will take much longer to drain.

When sealing pipes under the screed, you should wrap them with thermal insulation, then the noise of the water will not be so audible.

• In order to cut the required length of the pipe, use a grinder or a hacksaw, after which the cut part is chamfered.
• It is recommended to fasten the pipe every 10 diameters.
• Plastic sewer pipes - diameters ranging from forty to three hundred millimeters - require additional space for expansion due to increased temperature.

Compliance with these rules and, in particular, the diameters of sewer pipes when installing a household sewer system will allow it to remain in working condition for many years and will allow you to resort to repair work extremely rarely.