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Minimum slope for water flow in the sewer. Minimum, maximum slope of sewer pipe: optimal calculation. Calculation of sewer pipe diameter

The sewerage system is divided into two parts: internal and external. Internal system consists of outlets (from bathtubs, showers, sinks, toilets), a riser and outlet from the house. The external system consists of a pipeline and a storage tank or septic tank. Internal pipeline in turn, can be divided into vertical (risers) and horizontal (branches).

Sewage pipes

The vertical part requires ventilation and protection from clogging. Horizontal sections are called so conventionally, since in practice they are mounted at a certain angle relative to the horizontal surface.

Slope rate sewer pipes- snip 2.0401-85. This document also defines the conditions for installing the system from the exit from the house to the first well, which must be located no less than 12 m apart.

Calculation of the slope of a sewer pipe: basic concepts

If the sewage system is gravity-flowing, then its efficiency in transporting wastewater due to the laws of gravity depends entirely on the angle of inclination. It is believed that wastewater should move through the pipeline at a speed of 0.7-1 m/s. Only in this case is the flow able to remove solid particles from the system. To maintain the flow rate, the slope angle of the sewer pipe must be calculated for each individual diameter.

At first glance, it may seem that the angle should be measured in degrees. But in building codes and reference books on sewerage installations, this parameter is defined as a decimal fraction. These figures reflect the ratio of the level reduction to the length of a certain pipeline section.

For example, on a section of pipeline 5 m long, one end is 30 cm lower than the other. In this case, the slope of the sewer pipe will be 0.30/5=0.06.

Formula - determining the maximum, minimum value

wherein:

• V speed of fluid flow (m/s);
• H pipeline filling;
• d pipe diameter;
• K is the calculated slope coefficient.

To determine the coefficient (slope), you can substitute V = 0.7-1, d - the value of the diameter of a specific section of the pipeline, H = 0.6xd (according to building codes and regulations). It turns out that for a pipeline with a diameter of 100 mm per meter a slope of 2 cm is required, with a diameter of 50 mm - 3 cm per meter.

From the formula it is clear that the flow rate of wastewater directly depends on the angle of inclination (coefficient). For optimal speed you need minimum slope sewer pipe 0.02 and maximum - 0.03. If the tilt is less than 0.02, large particles will settle and form a blockage.

If the roll is too great, the speed will increase, which will also lead to the formation of precipitation, since the water will leave too quickly, not having time to take away the heavy waste particles. Increasing the flow rate can also lead to failure of siphons and constipation.

Necessary standards in the apartment

When installing a sewer system, there is no need to use a formula for calculations. There is a table that defines the slopes for all outlets from plumbing fixtures.

Each section of the sewerage system in the apartment must have a siphon at the end in the form of a device or a bend so that water does not enter the premises. unpleasant odors. To determine the required values, the principle of the golden mean is important - 1.5-2.5 cm per meter. This is quite enough for an apartment or country house. The use of formulas is necessary when constructing large facilities with a maximum volume of wastewater.

In addition, for domestic sewerage the formula is difficult to use since there is no constant flow. Here it is better to pay attention to another indicator - the ability to self-clean (remove solid particles).

Since domestic wastewater contains waste of different weights, the determining factor for heavy components is the flow speed, for floating ones - the filling of the diameter of the system. When determining the correct slope, it should be taken into account that it will be different in each individual area.

Slope of the external and internal parts of the system

In private country house It is necessary to arrange not only internal, but also external sewerage. In addition, outlets are needed for water that is formed as a result of melting snow and precipitation in the form of rain. Storm drainage can be installed together with the main system or separately.

The slope of the internal sewer pipe is strikingly different from the same indicator outdoor system. Pipe products are required for storm drainage large diameter(from 100 mm) and gratings, since this system will certainly get various pollution of plant origin. Sewer slope for storm water should also be greater - 0.05-0.07, but no more than 0.15.

External waste from the house is usually directed to a central sewer or septic tank and is laid underground. The diameter of this pipeline is most often 100-150 mm. Minimum slope- 0.02. Based on this, you should dig a trench. If at earthworks If there are any inaccuracies, the situation can be corrected using a sand cushion.

Any sewerage system must provide unimpeded flow for drains and guarantee high level self-cleaning. You should definitely take into account that the standards and textbooks indicate average indicators, so common sense and practicality will never hurt.

Good afternoon, dear subscribers of the construction portal site. In this article, we will walk you through the process of laying a sewer pipe, namely, we will pay attention to the angle of inclination of the sewer pipe. So let's go.

One of the main factors determining comfort in your home or apartment is the proper operation of the sewerage system. This issue is especially acute in old dwellings with cast iron sewer pipes. Over time, cracks and leaks appear in them. Nowadays the most popular material for the manufacture of sewer pipes is polymers. Plastic pipes are very easy to install and can be installed even by non-professionals.

Required tools and materials

For self-installation sewerage from plastic pipes you will need the following tools and materials:

• the pipes themselves (5 cm in diameter for drainage and 10 cm for risers),
• connecting elements (bends and fittings),
• sealing cuffs,
• special glue for plastic pipes,
• pencil, tape measure, building level, saw.
• if necessary, cement.

Getting ready for work

We inspect the old sewer system and record all its parameters. Can you take a photo of the design? old system, this will make it easier to install a new one.

1. Take a sheet of graph paper and draw up a diagram of the sewer pipe layout on it. Be sure to place plumbing fixtures and spacing between them, including central pipe boner
2. Check the drawing with the actual distances between the sewerage nodes in your apartment.
3. We recommend that you repeat old scheme routing of sewer pipes. It is usually made by professionals and there is no need to change it.
4. Based on their sketch and real distances, calculate required quantity plastic sewer pipes and connecting elements.

Video - sewer pipe slope and alignment

Calculation of the minimum slope of a sewer pipe

However, you can ignore algebra and use ready-made solutions.

Slope of horizontal pipe sections sewer system must be at least “0.02”. That is, on a section of a sewer water pipeline one meter long, the height difference at the ends of the pipe should be two centimeters.

However, with a small volume of transported wastewater, this figure can be increased to “0.03”. Thus, if you are laying a section of sewerage from one washbasin, then the level of the pipes should drop by three centimeters for each linear meter pipes.

1. Sewer plastic pipes have grey colour. Pipes different diameters designed to perform certain sewerage units.
2. There is no need to do calculations - just measure the diameter of the old pipes and select plastic pipes of the same diameter.
3. However, you can also use this reminder: when installing drains in washing machines and dishwashers, pipes with a diameter of 2.5 centimeters are used, when installing drains from showers and bathtubs - with a diameter of 3.2 centimeters, pipes moving drains around the apartment have a diameter of 5 centimeters, and those used for main risers are 11 centimeters.
4. In the same way, the footage is selected according to the length of the old pipes plastic sewer, after creating the circuit sewer distribution you will be able to calculate the number, as well as the configuration of the connecting elements.

Dismantling old pipes

After inspecting and measuring the old sewer system, drawing up a pipe layout with all connecting elements, you can begin to dismantle it.

1. We inspect old cast iron pipes, determine the elements that will require dismantling extra work(for example, pipes passing through walls.
2. We prepare the required tools.
3. We turn off the water supply in the room and warn the neighbors above about the start of dismantling work.
4. Carefully working with a chisel, we begin to dismantle the cast iron pipe, making sure that fragile fragments of cast iron do not fall into the main sewer system during dismantling - this can lead to its failure.
5. In order to dismantle the section of pipe adjacent to the main riser, you can simply saw it off with a grinder. This procedure is implied if you do not replace the main riser.
6. If connections cast iron pipes fixed with sulfur (this can be checked by the characteristic odor after heating the connections), then dismantling the connections of such pipes must be carried out using gas burner. Please note that this work is best done in a respirator.

Further installation work must begin after the connecting units have completely cooled.

Basic methods of installing plastic sewer pipes

There are two main ways to install plastic sewer pipes: using special glue or welding.

Adhesive installation of plastic sewer pipes:

1. Cut off the ends of pipes that exceed the dimensions required for installation.
2. Sand the cut edges
3. Remove grease and grease residue from the ends of the pipes and connecting elements.
4. Check the compatibility of the pipe sections being connected; they should fit together with little effort.
5. Place glue on the areas to be glued. More thick layer glue is applied to the connecting element, thinner glue is applied to the end of the pipe itself.
6. We connect the elements of the system; to distribute the glue evenly, rotate the pipe in the connecting element.
7. A bead of glue the consistency of liquid honey should form on the outer edge of the joint.
8. The time for the glue to completely dry and securely fix the elements is about one hour.

Welded installation of plastic sewer pipes:

1. We cut the mounted pipe to the right size, clean and degrease the areas to be joined.
2. Prepare a special soldering device and heat it up to 260 degrees
3. We fix the connecting element and the pipe section to the nozzles of the soldering device.
4. We heat the parts to be joined to the temperature indicated in the instructions.
5. Connecting heated parts
6. We check the connection point for any backlash, gaps, or polymer residues.

Some nuances for installing plastic pipes

The installation procedure for plastic sewerage pipes begins with the top unit, that is, the sewerage part located at the highest point. It is from this that the slope of plastic pipes for the free flow of wastewater will be calculated. The sockets of the connecting elements must be installed in the direction opposite to the normal flow of fluid. Control the angle of inclination of plastic sewer pipes using a building level that has the necessary marks. You can also control the angle of inclination using pre-set marks on the wall.

Often, when repairing the sewer system in apartment buildings, polymer plastic pipes have to be joined to old cast iron ones. So in the vertical section of the sewer system in apartment building You can use special fittings to insert a section consisting of a plastic pipeline.

It is also necessary to remember that horizontal sections of the sewer system should not be adjacent to vertical pipes at right angles. Typically, at least two pipe bends are used for this, each of which turns the wastewater flow by 45 degrees. In this way, you will reduce the turbulence of the wastewater flow and design the correct “input” of your sewer into the common house.

When designing a home drainage system, it is important to understand which sewer pipe slope is optimal. Despite the apparent simplicity of the structure, the wrong choice of descent angle will lead to the most unpleasant consequences, and all the work will have to be redone. As a rule, home sewerage operates by gravity, so it is obvious that insufficient slope will lead to poor flow, and the reverse will completely prevent the normal operation of the system.

What's wrong with excessive bias?

Inexperienced builders may be tempted to make the pipe as inclined as possible so that the waste flows out faster. But this approach is also wrong. If the descent is too steep, the pipe becomes silted due to the fact that the water drains too quickly, without having time to wash away the more solid fractions of sewage, which then stick to inner surface. In addition, water locks in siphons may fail, which means air from treatment system will enter residential areas. Is it worth explaining in more detail what kind of smell it will bring to them?

There is another reason why pipes should not be left underfilled. In aggressive environments, the flow of air to surfaces leads to accelerated corrosion, and as a result, their service life is reduced.

Determining the slope value

The main difficulty faced by novice builders and those who independently carry out drainage is that the unit of measurement for slope is unusual for them. All reference books and even building codes, which are the main guide for any builder, indicate decimals type 0.03 or 0.008.

People accustomed to working with degrees do not understand what slope of the sewer pipe these numbers mean. Everything is very simple: this fraction is the ratio of the height of descent to the length of the pipe. The easiest way to track it is in centimeters, for example 3 cm by 1 m, or 0.8 cm by 1 m, as in the examples given. The length of the sewer pipe in meters when multiplied by the slope will give overall height slope for the entire duration.

For example, if the total length is 5.6 meters, and a reduction of 0.07 is required, then there must be a difference between the levels of the beginning and end of the pipe:

H=5.6 x 0.07 = 0.39 m, that is 39 cm.

Calculation of pipe fullness

The main parameter that should be followed when laying a sewer pipe should be its fullness. It is calculated by the formula: y = H/D,
Where:
H is the height of the water level in the pipe;
D is the diameter of the sewer pipe.

Wherein:
if y=0, then the pipe is empty;
if y=1, it is completely filled;
The optimal value for fill (K), at which the drain works normally, is in the range from 0.5 to 0.6.

This scatter is explained various properties pipe materials and their ability to form a boundary layer held near the inner surface of the pipes.

Thus, glass or plastic pipes have a smoother inner surface, and their filling should be 0.5, while ceramic or asbestos pipes are rougher, and for them this value is 0.6.

The described filling value will ensure a flow rate of approximately 0.7 m/s, which will keep solids in suspension, preventing them from sticking to the walls of the pipeline.

Thus, the design characteristics of the pipeline should be determined by the formula: K ≤ V√ y,
Where:
K - optimal filling level (0.5 or 0.6);
V - speed;
√ y – Square root pipe fillability.

How to measure the slope angle

The minimum slope of the sewer pipe in the apartment depends on the diameter of the pipes being laid. According to SNiP for 50 mm pipes it is 0.03, that is, 3 cm per meter, and for “one hundred” or 85 mm - 2 cm.

Slope of external sewerage pipes

The building codes and regulations indicate optimal sizes slope of external sewerage pipes, which have a larger diameter compared to internal communications.

This means that for a pipe with a diameter of 100 or 110 mm, the slope should be 0.009. This will be 9 cm. If the length of the pipe is 6 meters, then the slope should be 56 cm. That is, the lower point of the pipe should be 56 cm lower than the top.

Special conditions mean the need to create a system when, for production reasons, it is impossible to create the required slope, in other words, this is the utmost permissible level reduction when something interferes with creating the optimal slope of the external sewer pipe.

There is also a maximum value for this parameter. It is 0.15, that is, with a decrease of more than 15 centimeters for every meter of pipe, the system will work extremely inefficiently, the pipe will silt up when the water quickly drains and will clog very quickly. Water simply will not have time to wash away solid waste.

When calculating the slope, you can take into account other features of the system, for example, the nature of the load. If the drain is made from an ordinary washbasin, then there is no need to worry about silting, and the slope can be made large enough, but still such that it does not allow the water seals in the siphons to break.

Slope 0.15 – maximum permissible under all conditions

Summarizing all of the above, we can conclude that the optimal amount of reduction in a sewer pipe is in the range from 15 to 25 mm per meter of pipe.

The wastewater system is an integral part of any home. In order for it to function correctly, you need to arrange it correctly, that is, choose the right angle at which it will be laid. Many people ask a well-founded question whether, according to SNiP, a sewerage slope of 1 meter will be sufficient or whether it needs to be made larger (or maybe smaller). Let's figure it out.

On a note! Even if you arrange the wastewater system at the right angle, this will not guarantee normal and durable sewer operation. Since there are a number of other points that need to be taken into account when installing it: location (pipeline layout indoors or outdoors), configuration, diameter and material of pipes.

Why is the tilt angle needed?

Why do we need a very specific angle of inclination of the wastewater system? Maybe it’s enough to just lay the pipes and not “bother” about how to make the sewerage slope 1 meter - the recommended values ​​according to SNiP?

The main arguments for installing a sewer system at a certain angle:

• Without it, the liquid will begin to stagnate in the pipes (and this is not good).
• The sewerage system must function without any failures, despite the impossibility of predicting the consistency and nature of the wastewater.
• The main purpose of arranging a slope is the desire to practically minimize the possibility of settling of solid fractions (or sludge) on the walls of the laid pipeline.
• Ensure silent operation of the system, while preventing the backflow of wastewater and eliminating the unpleasant odor directly in the room.

Too little slope or too much - which is better?

The most important thing is to determine exactly the minimum slope, since if it is too small, the wastewater will not flow out completely. As a result, you will inevitably end up with clogged pipes and all the ensuing consequences.

Fine. Maybe then make a large slope and be sure that everything is in order with the leakage of liquid and not do the calculations minimum angle so that the slope of the sewer pipe by 1 meter - recommended by SNiP - is observed? No, it's bad again. This is not an option. The fact is that if the slope is too large, large fractions are absolutely guaranteed to accumulate in the pipe and contribute to the formation of a blockage. The fact is that with a very large slope, the liquid quickly flows out, and to remove solid elements it takes more time (and there is nothing to wash them off with). As a result, the pipe is clogged and you panic.

It turns out that we need to find “ golden mean", namely, to determine the minimum angle of inclination of the wastewater system so that it functions well. If the design and installation of the sewer system are carried out strictly according to the standards of such a document as “ Building codes and rules”, that is, the sewerage slope of 1 meter (SNiP recommended values) is maintained, this will significantly increase the service life of the system that removes wastewater, and, naturally, the quality of its work.

Calculate the minimum angle of inclination

To determine the minimum angle of inclination, it is necessary to perform mathematical calculations using a certain formula. Here it is - V√H⁄D≥K: V - liquid drainage speed (optimally, it is 0.7 m/s); H - waste liquid level (that is, it determines the degree of filling of the pipeline and should be about 50-60%); D - pipeline diameter; K is the pipeline slope coefficient (optimally, it should vary from 0.5 to 0.7; that is, the closer to 1, the better).

Important! The degree of filling of the pipeline should not be less than 1/3.

Pipeline slope coefficient

This indicator can be determined in two ways:

• Calculate it yourself using the formula - H/D.
• Refer to reference material.

On a note! The value of this coefficient indicated in the reference book is directly dependent on the material from which the pipes are made: 0.5 - for glass and plastic; 0.6 - for materials such as cast iron, asbestos cement or steel. Also, do not forget about the degree of roughness of the inner surface of the pipe, which negatively affectsK.

It is known from practice that approximately a slope of 20 mm (per 1 meter of sewerage pipeline) will be sufficient.

Pipe diameter

If you don’t want to make any calculations, you can do without them: it is possible to determine the required slope of the sewer system depending on the diameter of the pipes. Practical, convenient and fast.

Naturally, all this can be done if the diameter is selected in such a way that the conditions for pipeline fullness (50-60%) and fluid velocity (0.7 m/s) are met. Otherwise, nothing will work.

As a rule, the calculation simply comes down to choosing a certain diameter (200, 150 (160), 100 (110), 80, 50 mm) and specifying the angle of inclination accordingly.

Important! Don't forget about the margins of error.

In SNiP, depending on the diameter, the values ​​of the minimum and maximum slopes are presented. If you multiply these values ​​by 100, you will get these figures in centimeters.

Important! All these values ​​can be used for arranging slopes exclusively on flat areas (that is, without connecting to outlet pipes, siphons and other systems).

Wastewater system location

There are two wastewater systems:

• Internal. This is a set of pipelines that ensure the removal of existing wastewater from plumbing devices and their removal outside the building. Most often, owners of private houses arrange such a system on their own. Good for construction market A wide range of different plastic elements is presented.
• An external wastewater system ensures the delivery of wastewater from the building to the septic tank (storage and treatment complex).

Internal piping

Besides the slope internal sewerage per 1 meter (SNiP recommended values), you must adhere to the following recommendations:

• We use pipes with a diameter of 100, 80, 50 or 40 mm (and a diameter of 100 mm is used to connect zones general purpose, that is, in places where pipelines converge).

• We make the most optimal slope values ​​for pipes of these diameters, namely: 0.015, 0.2, 0.03 and 0.035, respectively.
• If according to technological process it is necessary to use adapters (for example, when moving from bigger size to a smaller one) we do this in such a way that the evenness of the lower part of the channel is not disturbed. Otherwise, the continuity of water flow may be disrupted.
• We provide the required slope using fastening systems or the slope of the box in which we install the sewer system.

On a note! We make sure to maintain the required slope when installing the pipeline from the device to the sewer system. Moreover, we equip the turn to such a system with a tee or elbow (the inclination should be about 70 degrees).

• We do not allow pipes to bend at right angles. We use exclusively bends (at 45 degrees and only).

On a note! If the pipe is of insignificant length, then deviation from a certain slope is quite acceptable.

External piping

In addition to the slope of the external sewer system by 1 meter (SNiP recommended values), the following recommendations must be adhered to:

• Depending on the soil and climatic conditions The depth of the trench can vary between 100-200 cm.
• To correctly carry out the required slope, do not forget to take into account the ever-increasing recess. To do this, we initially make the depth deeper by 25 centimeters, so that it is convenient to arrange a sand support for the system.

• We carry out the line at a depth below the freezing level (350 mm). When laying above the level, it is worth considering enhanced thermal insulation.
• The diameter of the pipes used is 110-200 mm. In this case, the minimum slope is: 200 mm - 7 mm, 160 mm - 8 mm. But according to SNiP, the sewer slope per 1 meter (110 mm pipe in diameter) is about 20 mm.

Remember! If you want the slope to be most effective, follow the rule: the slope is no more than 150 mm (based on each linear meter).

• We place the pipes at the same level, without changing the slope along the entire length.

Remember! It is unacceptable to combine pipes of different diameters. Also, level differences in the gasket should not be allowed. If such a need arises, then the equipment manhole Necessarily.

Storm drain

Function storm sewer- drainage of melt and rain flows (to avoid waterlogging of the area and preserve the foundation of the building).

In addition to the slope of 1 meter (SNiP recommended values), other factors must be observed, namely: the type of drainage system and the diameter of the pipe.

On a note! The minimum slope for drainage of melted water should be as follows: 7 mm (for pipes with a diameter of 200 mm) and 8 mm (for 150 mm).

In addition, other points need to be taken into account: characteristics local soil, average precipitation for the region of residence and the volume of wastewater.

Pipe configuration

Is the condition of a sewer slope of 1 meter (SNiPom recommended values) the only one for quality work sewage system? No. There is one more important condition, without which blockage is inevitable. This is the configuration of the laid pipeline. After all, if it is too “sophisticated” and has a large number of bends, then wastewater will not be able to quickly flow (without lingering inside the pipes) into the collector, and then straight into sewage treatment plants. In this case, no sewer slope of 1 meter (SNiP recommended values) will save the situation.

Pipe material

Can be:

• plastic;
• cast iron;
• concrete;
• asbestos-cement;
• ceramic.

Most often, plastic pipes are used for the construction of an internal sewer system, and asbestos-cement, cast iron or corrugated pipes for an external one.

Finally

After reading the article, it becomes clear that the maximum (recommended by SNiP) will not solve the problem, but will aggravate it. Only correct solution- determination of the minimum angle of inclination. And, of course, do not forget about the configuration and material of the pipeline. And you will be happy.

When laying sewer pipes in a private house or major renovation apartments (with replacement of sewerage and water supply networks), it should be remembered that the principle of drainage in them is based on the work of gravity. This means that without outside intervention, movement in the sewer system will only occur when there is a slope in the sewer pipe.

In domestic conditions, when installing sewer pipes with your own hands, there is no point in installing pressure system for forced pumping of wastewater using a pump. This leads to additional costs both during construction and during the operational period, and their repair, if necessary, is quite expensive. Forced drainage network systems are used only in large industries.

Contents of the article

Main settings

When laying sewer pipes with your own hands in a private house, it is very important to create the correct slope, following all the rules when installing them. Slope too small will result in weak flow inside the line, which will allow heavy components to be deposited and will require repair of all networks in the future.

A large angle of inclination of the sewer pipe is also not suitable, since in such conditions waste water will go away faster than other components, which will also lead to clogging of the entire system and you will have to dismantle it to correct the situation.

The rules for properly laying a sewer pipeline are to ensure sufficient speed of movement of wastewater. This indicator is one of the main ones, and it determines how efficiently the entire sewage system works.

The statement that the greater the slope of the pipe, the faster the flow moves, and the more better job the entire system is erroneous. At large slope, indeed, the water will leave very quickly, but this is the mistake - with the high-speed passage of water in the line, the self-cleaning of the system is significantly reduced.

Large and heavy particles that fall into the sewer along with water will not have time to travel the entire way and will remain in it, gradually accumulating and creating blockages.

In addition, this approach leads to noisy operation of the sewage system, and due to the high speed of movement, it will increased wear of the inner surface occurs.

This will lead to premature replacement of individual sections or the entire sewer system will have to be repaired.

According to the rules for installing sewer pipes, the optimal speed of movement of wastewater should be from 0.7 to 1 meter per second.

Since the speed of movement of wastewater is set by the slope of the sewer pipes, there is another parameter, which is expressed by the difference in height at the beginning of the pipeline (the highest point) and its end (the lowest point of the entire system).

The slope per 1 linear meter of sewer pipes in centimeters in height is the parameter that must be observed when laying sewers. You will have to adhere to the standards for this value, since otherwise it will be necessary to dismantle the entire system, and sometimes repair or alter the water supply system.

Standards

When laying sewer pipes in a private house, you must follow the rules described in SNiP 2.04.01-85.

Taking into account the diameter of the pipeline, the sewerage is laid with a certain slope for each linear meter.

For example:

• if lines with a diameter of 40-50 mm are used, the slope should be 3 cm per linear meter;
• for pipes with a diameter of 85-110 mm, a 2-centimeter slope per linear meter is optimal.

In some cases, slope parameters are expressed in fractional numbers, and not in centimeters per linear meter. For the above example (3/100 and 2/100), slope information at correct laying sewer pipes in a private house will look like this:

• for lines with a cross section of 40-50 mm – slope 0.03;
• for lines with a cross section of 85-110 mm - slope 0.02.

Individual slope calculation

Laying sewer pipes with your own hands in a private house is carried out according to the standards that appear in SNiP. But you can calculate the parameters for the arrangement of sewerage and water supply networks yourself. To do this, use the following formula:

V√H/D ≥ K, where:

• K is a special coefficient that takes into account the properties of the material that was used in the manufacture of the pipe;
• V – speed of passage of wastewater;
• H – pipe filling capacity (flow height);
• D – section (diameter) of the pipe.

Explanations:

• coefficient K, for pipes made of smooth materials (polymer or glass), should be equal to 0.5, for a metal pipeline - 0.6;
• indicator V (flow velocity) - for any pipeline is 0.7-1.0 m/s;
• H/D ratio - indicates the filling of the pipe, and should have a value from 0.3 to 0.6.

Internal and external sewer systems

When laying sewer and water supply networks in a private house, some features should be taken into account, which are determined by the location of their individual sections.

Internal systems

When installing sewer pipes in a private house, two diameters are mainly used - 50 mm and 110 mm. The first is for drainage, the second is for the toilet. The laying of the sewer pipe should be carried out in accordance with the following recommendations:

• turning the pipeline (if it horizontal position) should not be done at an angle of 90 degrees. To change the direction, it is better to install the bends at an angle of 45 degrees, this greatly facilitates the passage of the main flow and reduces the likelihood of accumulation of solid particles;
• in places where the system turns, fittings should be installed for inspection and ease of cleaning or dismantling in case of clogging;
• in short individual sections, it is permissible to increase the slope, exceeding the recommended norm. Such short branch there may be a sewer pipe connecting the toilet to the riser;
• in each individual section, the slope of the pipeline must be uniform, without sudden changes, because their presence can create conditions for the occurrence of a water hammer, the consequences of which will be the repair or dismantling of an already operating system.

Do-it-yourself sewerage installation in a private house (video)

External (external) systems

Correct laying and installation of sewer pipes is necessary not only inside, but also outside a private house, from the point of exit of the internal sewerage system to the septic tank.

Therefore, you should pay attention to the following points:

• laying of sewer networks is carried out in trenches with a depth of 0.5 to 0.7 meters. The depth of penetration depends on the characteristics of the soil and is adjusted to specific conditions;
• When preparing trenches, sand should be used at the bottom to make it possible to establish correct slope due to its bedding;
• highlight the pre-calculated slope (per linear meter) as a guide from the cord stretched between the driven pegs. This will avoid unnecessary subsidence or elevation of the sewer system in certain areas;
• After laying the pipes at the bottom of the trench, check again for the correct slope and, if necessary, correct it using a sand cushion.

Storm drain

The system is also demanding on slope, and its presence is mandatory to eliminate water accumulation on the soil surface during precipitation.

When , the same parameters are taken into account as for the main sewerage system - the diameter of the pipe and the material from which it is made. Average slope indicators:

• for pipes with a diameter of 150 mm - the indicator varies from 0.007 to 0.008;
• with a 200 mm section – 0.005 to 0.007.

On private farmsteads You can get by with open storm drains.

But even with such a water drainage system, the slope must be present:

• – 0,003;
• for concrete trays (semicircular or rectangular) – 0.005.

When laying sewer pipes, what slope of the sewer pipe should be?

For normal sewerage operation, the slope must be in accordance with the recommended standards according to SNiP, or calculated using a special formula.

Expression - than more slope- the better and faster the drain - a mistake that should not be made in order to avoid the subsequent dismantling of a completely new sewer system.

If you adhere to time-tested and operational standards, the sewerage and water supply systems will not require repair or dismantling for many years.