What slope is needed for sewage. What should be the slope of the external sewage pipes

Sewerage in a private house is a necessary engineering design, the purpose of which is to increase the comfort of life of residents. The optimal arrangement of sewage systems inside the house and beyond is considered a simple and very important task. This question should be approached with full information, because in this case the whole range of work can be done independently.

What is the slope of the sewer pipe?

The external sewage system assumes the presence of pipes for the drain from the house of already spent liquid. To ensure that the outflow meets the necessary installation requirements and is correct, the sewer pipes are installed at a certain angle. This angle is measured in fractions (decimal) and calculated by a special formula.

Where is it considered that:

H - pipeline filling;
V is the discharge rate of water in m / s;
K is the slope coefficient;
D is the diameter of the pipe.

To find out the slope level of the pipe (sewer) without using calculations, you can apply the already known indicators, which will depend on the diameter of the pipe per meter length. If the pipe has a diameter of 50 mm, then the pipe edge should be 3 cm higher than the lower edge after 1 m. A pipe (sewer) with a diameter of 160 mm must be mounted in such a way that the inclination is not less than 0.8 cm.

Why is the slope of the sewage system so necessary?

Gravity drainage is a standard solution for private homes. In order to serve the owners for many years, it is necessary to correctly adjust the inclination of the drain system. It should be borne in mind that the angle of inclination should not be very significant, because this can affect the operational properties of the sewage system.

Let's consider in more detail:

For example, the pipe may break, because the solid fractions will be poorly washed off due to the rapid flow. This can contribute to the formation of sludge inside the sewer pipe, and therefore it will be necessary to clean the pipe in the future.
If during installation metal pipes choose the wrong angle of inclination, then the upper part during the discharge will be filled with air, because of which it will occur, and the pipe itself will fail.
If the pipe is long and strongly inclined, then there is the possibility of a siphon breakdown. In other words, the sewage system will be disrupted, and all the unpleasant smell will spread throughout the house.

In addition to the factors listed above, an increase in the angle of inclination of the pipe will also significantly increase the noise level during the washing off of feces and the runoff of used water in sewer pipes.

How is the angle of slope of the pipe calculated?

The main parameter that must be used in the process of calculating the slope of the pipe is the flow rate of the wastewater. Such an indicator is determined by the normative value (a special SNiP called “Slope of gravity sewage”), while the minimum speed of wastewater should be 0.7 m / s (no more). It is allowed to use only the recommendations of the regulatory document, it indicates the various nuances for the installation of the sewer.

SNip also reflects the nuances of the device storm sewer, domestic sewage, and also indicates the fact that during the calculation of the angle of inclination, it is necessary to take into account another important indicator - the filling of the pipe. The value of this indicator (normative) is not less than 30% and depends directly on the flow rate, as well as on the diameter and material of the sewer pipes.

So that after the calculations, the sewage system is mounted at the correct angle, it is necessary to perform certain land works. Various irregularities at the bottom of the trench can cause the sewage system to malfunction. In this regard, before laying and further connecting the pipes, you should check what level of trench inclination.

To calculate the slope of the sewage system by 1 meter, it is not necessary to use a special SNiP. For example, you can apply tips already calculated indicators for certain pipe diameters. Consider well-known factors: for pipes with a diameter of not more than 50 mm for each running meter, the slope should be no more than 3 cm, for polypropylene sewer pipes with a large diameter (110 cm), the slope should be 2 cm per 1 meter of sewer pipe.

If we consider the wiring of the internal sewage system, then it is a layout of pipes in the house, with each place where the pipe is used has different diameters. Based on this, the angle of inclination inside the house is not determined solely by one value.

If the pipe departs, for example, from a shower cabin, bathtub, sink, then with a diameter of 40-50 mm the slope of the pipe should be at least 2.5 cm per meter of length and a maximum of 3.5 cm per 1 meter of sewer pipe.
If to the sewer pipe (with a diameter of 10 cm), then the angle of inclination can be 1.2-2 cm per 1 meter of pipe.

To measure the necessary slope indoors, various building levels are used: from modern laser ones, with which you can find out the right direction, ending with small magnetic levels, they are installed on the pipe itself. Such levels have 3 stripes on both sides, with each of them equal to 1 cm slope.

In the process of laying the external pipeline, it is also necessary to take into account both the calculated values \u200b\u200bof the slope and the filling of the pipeline. For example, for high-rise buildings, in which a large number of residents respectively live, the volume of wastewater, as a rule, will be much larger in comparison with private houses.

During the construction of such houses, as well as the arrangement of their sewage system, the occupancy rate of the pipe is also taken into account so that the sewage system operates without interruptions. In this regard, the angle of inclination of pipes (sewer) in multi-storey buildings is determined separately, but it is also necessary to be guided by SNiP.

As for private houses, then calculations are made for the sewer device or special recommendations are applied. Do not forget about non-standard situations. For example, laying pipes below a previously calculated level, the depth of freezing of the soil, or some other reason, should help to increase the level of the slope of the sewage system.

The main task with the sewage system is to ensure that the drains do not clog the pipe. If the slope changes are very sharp, all solid waste can accumulate in the sewer, which will contribute to the appearance of clogging and alteration of the sewer in the future. To know the slope of the sewage system by 1 meter outdoors is possible with the same devices as inside the house.

The use of a variety of tools during the laying of sewers is the right and reasonable decision. By sight, as practice shows, it is almost impossible to find out the required level of slope and in the process of installing pipes to make sure that it does not change in the future. In this regard, during the sewage system, various devices are used - or a hydraulic level, level, other devices.

You can find out the length of the sewer pipe as follows: first, all pipes are connected into one, after which the optimum slope is set using the level. It is worth noting that this alone will be quite difficult to do. One person must adjust the level of the pipe, while the other should lead the process and monitor the level marks.

If you decide, then it is better to choose a tool with a round recess at the bottom. Thanks to this factor, it will stay on the pipe much stronger, while its position will be adjusted. It is very convenient to use such a level on metal pipes, since a special magnet is built into its bottom, which will keep the level on the pipe.

Laying sewer pipes inside the house and setting the required level is the easiest process compared to other works, because you can use any tool (even a standard ruler) to determine the angle of inclination.

Sewer pipe slope

Sewerage in your own house is a necessary engineering system that increases comfort for the residents of the cottage or cottage. Proper arrangement of the sewage system, both inside the house and outside it, is an important and uncomplicated task. The main thing is to approach the issue with full awareness, then it will be possible to do all the work yourself.

What is sewer pipe slope?

An external sewage system involves conducting pipes to drain the spent liquid from the house. In order for the outflow to be correct and meet all installation requirements, sewer pipes must be placed at a certain slope, which is calculated by the formula and measured in decimal fractions.

V is the discharge rate of wastewater in m / s;
H - pipeline filling;
D is the diameter of the sewer pipe;
K is the slope coefficient.

In addition to calculations, to determine the level of the slope of the sewer pipe, you can already use known indicators depending on the diameter of the pipe per 1 meter of its length. For pipes with a diameter of 5 cm, the top edge of the pipe should be 3 cm higher than the bottom after 1 meter. Sewer pipes with a diameter of 11 cm should be installed with a slope of at least 2 cm per meter pipe lengths. A pipe with a diameter of 16 cm should be mounted so that the slope is at least 0.8 cm.

What affects the slope of the sewer pipe

Gravity drainage is a standard solution that is used in private homes. In order to prevent sewage pipes from clogging and lasting as long as possible, you need to correctly set the slope of the drain system. The angle of the sewer pipes should not be too large, as this will affect its operational properties.

The pipe can quickly fail, as it turns out that the solid fractions will not be washed off due to the rapid flow. And this in turn can lead to the formation of sludge inside the sewer pipe and its subsequent cleaning.
If the pipe is strongly inclined and at the same time long, then the siphon shutter may be disrupted, that is, the sewage system will be disrupted, and all the unpleasant smell will rush into the house.
When using metal pipes and the wrong choice of the angle of their inclination, when draining, the upper part will be filled with air, which will contribute to the development of metal corrosion and the failure of the pipe.

In addition to the listed negative factors exceeding the angle of inclination of the pipes will significantly increase the noise level during the drain of used water and flushing of feces.

How to calculate pipe angle?

The main parameter that you need to use to calculate the angle of the sewer pipe is speed of movement sewage flow. It is determined by the normative value (SNiP "Slope of gravity drainage"), the minimum flow rate is 0.7 m / s. Only recommendations can be used. normative document which indicates all the nuances for the sewer device. At the same time, SNiP reflects such moments as the device of internal sewage and storm sewage. and also indicates that when calculating the angle of inclination, you need to focus on one more indicator - pipe fill level. The normative value of this indicator is at least 30%, but it directly depends on the flow rate and on the material and the diameter of the pipes.

In order that after calculations, the sewage system is installed at the correct slope, land works. Any unevenness at the bottom of the trench can cause sewage to function improperly. Therefore, before laying and connecting the pipes, you need to check the level tilt of the trench.

It is possible to calculate the level of pipe inclination without resorting to reading SNiPa, for example, use the recommendations already calculated indicators for a specific pipe diameter. Well-known facts are as follows: for pipes with a diameter of not more than 50 mm, the slope for each running meter should be no more than 3 cm, and for sewer polypropylene pipes of large diameters. for example 110 mm - 2 cm per 1 meter of pipe length.

How to measure the angle of the pipe?

The layout of the internal sewage system involves the laying of pipes inside the house, and each of the places of water use different pipe diameters therefore, the angle of inclination inside the house cannot be determined by only one value.

For pipes that extend from sinks, bathtubs or showers, with a diameter of 40-50 mm, the slope of the sewer pipe should vary from a minimum of 2.5 cm per meter of length, to 3.5 cm per linear meter of the pipeline.
When connecting the toilet to the sewer pipe. 10 cm in diameter, its angle of inclination varies from 1.2 cm to 2 cm per 1 meter.

In order to measure the required slope indoors, you can use different building levels - from laser, which can determine the correct direction, to small magnetic levels that are installed on the pipe itself. They have 3 stripes on each side, each of which equal to 1 cm slope.

When laying an external pipeline, it is necessary to take into account not only the calculated values \u200b\u200bof the slope, but also pipeline occupancy. So, for houses of large number of storeys, respectively, and the number of people living in the house, and therefore the amount of sewage, will be much more than the values \u200b\u200bgiven for private houses. During the construction of a house and the arrangement of sewers, take into account, among other things, the pipe fill rate so that the sewage system in the house worked without interruption. Therefore, the angle of the sewer pipes in a multi-storey building for each project is determined separately, but guided by this SNiP.

In a private house, for the sewage system, they make calculations or use recommendations. The only thing to consider is the so-called non-standard situations. For example, the depth of freezing of the soil or the laying of pipes below a predetermined level for other reasons, should contribute to an increase in the slope of the sewer. Since the main task in its arrangement is that drains must not clog the pipe. And if the slope is too sharp or if it is unreasonably increased, all solid waste will accumulate inside the sewer. This will inevitably lead to clogging and alteration. You can measure the incline level outdoors using the same devices as at home.

Sewer slope and their methods of exposure

The use of various tools in the process of laying sewers is a reasonable and correct solution. Almost impossible to determine by eye acceptable slope and during the installation of pipes to make sure that it does not change. Therefore, when a sewage device is used various devices - level, water or normal level and other devices.

For long sewer pipes (the total length of the entire line) can be done this way: first connect all the pipes into one, and then use the level set the correct tilt. But it's hard to cope alone. Since while one person is adjusting the level of the pipe, the other should follow beyond the level marks and lead the process.

If you use a water level, it is better to choose one that has a circular recess at its bottom, since it will hold onto the pipe while you can adjust her position. It is especially convenient to use this level on metal pipes, because a magnet is built into its bottom, which will hold the level on the pipe.

Inside the house, laying sewer pipes is the easiest in terms of setting the required level, since you can use any tool to determine the angle of inclination (up to the usual ruler).

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When designing a home drainage system, it is important to understand which slope of the sewer pipe is optimal. With all the apparent simplicity of the construction, the wrong choice of the angle of decline will lead to the most unpleasant consequences, and all the work will have to be redone. As a rule, home sewage works by gravity, so it is obvious that insufficient slope will lead to poor passage, and the reverse will completely exclude the normal operation of the system.
Why is excessive bias bad?
Inexperienced builders may be tempted to make the pipe as inclined as possible so that sewage goes away faster. But such an approach is incorrect. If the descent is too steep, siltation of the pipe occurs due to the fact that the water comes off too quickly, not having time to wash off the harder fractions of sewage, which then adhere to the inner surface. In addition, disruption of water constipation in siphons can occur, which means that air from the treatment system will enter residential premises. 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 unfilled. In aggressive environments, the influx of air to the surfaces leads to their 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 perform drainage is that the slope unit is unusual for them. All reference books and even building codes that are the main guidance of any builder indicate decimal fractions of the form 0.03 or 0.008.
People who are accustomed to operating degrees do not understand what slope of the sewer pipe these numbers mean. Everything is very simple: this fraction is the ratio of the drop height to the length of the pipe. The easiest way to track it is in centimeters, for example 3 cm per 1 m, or 0.8 cm per 1 m, as in the above examples. The length of the sewer pipe in meters when multiplied by the slope value will give the total slope height over the entire duration.
For example, if the total length is 5.6 meters, and a decrease of 0.07 is required, then there should be a difference between the levels of the beginning and end of the pipe:
H \u003d 5.6 x 0.07 \u003d 0.39 m, i.e. 39 cm.
Pipe fullness calculation
The main parameter that should be followed when laying the sewer pipe should be its fullness. It is calculated by the formula: y \u003d 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 \u003d 0, then the pipe is empty;
if y \u003d 1, it is completely flooded;
the optimal value for fullness (K), at which the drain works normally, is a range from 0.5 to 0.6.
This scatter is explained by the various properties of the pipe materials and their ability to form a boundary layer held near the inner surface of the pipes.
So, pipes made of glass or plastic have a smoother inner surface, and their occupancy should be 0.5, and ceramic or asbestos pipes are rougher, and for them this value is 0.6.
The described occupancy value will provide a flow rate of about 0.7 m / s, which will allow solid inclusions to be kept in suspension, preventing their adhesion to the walls of the pipeline.
Thus, the design characteristics of the pipeline should be determined by the formula: K ≤ V√ y,
Where:
K is the optimal level of occupancy (0.5 or 0.6);
V is the speed;
√ y is the square root of the tube occupancy.
How to measure the angle of slope
The minimum slope of the sewer pipe in the apartment depends on the diameter of the laid pipes. According to SNiP for 50 mm pipes it is 0.03, that is 3 cm per meter, and for “weaving” or 85 mm - 2 cm.
Pipe slope outdoor sewage
The building codes and standards indicate the optimal slope dimensions of the external sewage pipes, which have a larger diameter compared to internal communications.
So for a pipe with a diameter of 100 or 110 mm, the slope should be 0.009. It 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 upper one.
Special conditions mean the need to create a system when, for operational reasons, it is impossible to create the necessary slope, in other words, this is the maximum permissible level of decline when something prevents the creation of the optimal slope of the external sewer pipe.
There is a maximum value for this parameter. It is 0.15, that is, with a decrease of more than 15 centimeters per meter of pipe, the system will work extremely inefficiently, the pipe will silt up when water converges quickly and will clog very quickly. Water simply will not have time to wash off solid sewage.
When calculating the slope, other features of the system can be taken into account, for example, the nature of the load. If the drain is made from a conventional washbasin, then you should not be afraid of siltation, and the slope can be made large enough, but still so that it does not allow the breakdown of water locks in siphons.
Slope 0.15 - the maximum allowable under any conditions
Summarizing all of the above, we can conclude that the optimal decrease in the sewer pipe is in the range from 15 to 25 mm per meter of pipe.

When building a new building, whether a private house, a bathhouse or even a workshop, almost always the question arises of a sewage system.

As a rule, gravity drainage systems use gravity sewage systems.

First you need to determine what should be the minimum slope of the sewage system, since the depth of the laying of sewer pipes in a house or land, and, accordingly, the location of the plumbing elements: sinks, toilets, bathtubs, etc., will directly depend on this.

Sewer slope - norms and rules of calculation

There is a standard that uniquely defines the angle of the sewer pipe. This is SNiP 2.04.01-85, where literally everything is painted on the sewerage device inside the building, or as it is also called in another way “fun system”.

The SNiP rules determine all the necessary conditions for the calculation of external sewage systems. It should be noted that the correct calculation and implementation of the sewer device will save you from unnecessary additional hassles in the future.

Maximum / minimum angle of inclination of the sewer pipe - calculation

There are two parameters for the slope of the sewer pipe: minimum and maximum. “Rules ...” prescribe different slopes for pipes inside buildings and pipes of the external sewer system.

So, pipes with a diameter of not more than 100 mm are almost always laid inside buildings. The following standards apply for them:

The minimum slope of sewer pipes with a diameter of up to 50 mm should be 3 cm / m, and with a pipe diameter of 100 mm, the slope will be 2 cm / m.

The laying of external sewage systems, as a rule, is carried out by pipes with a diameter of 150 and 200 mm. For them, slopes are determined: 150 mm - 8 mm / m, 200 mm - 7 mm / m.

In any case, the maximum slope of gravity drainage should not exceed 15 cm per linear meter of the system. It would seem that the greater the slope, the more truly the water will leave the pipe without delay. But, in addition to water, solid particles are always present in the fan system, which must be washed off. And they move slower than the water itself.

Practice has shown that for the best discharge, the water velocity should be at least 0.7 m / s, and the water level should be at least 30% of the diameter of the pipe. Based on these considerations, all the necessary calculations are built. There is a formula for calculating the slope of sewer pipes:

where the first factor indicates the speed of water in the system, the second, under the square root sign, represents the fill factor of the system, not less than 0.3. The result should be greater than or equal to 0.5 for pipes made of glass or plastic, or 0.6 for pipes made of other materials.

In an absolutely overwhelming number of cases, the above values \u200b\u200bare suitable for use in practice.

The maximum slope of the sewage system can be exceeded if the distance from the device to the system is not more than 1.5 m. For example, leaving the toilet.

If the height difference is such that it requires a larger slope, you should put a vertical piece of pipe, and then continue wiring the system with acceptable slopes. Otherwise, the system will turn black after a while.

Pipes with a diameter of:

40-50 mm - for the sink
85-100 mm - for the toilet
100 mm - total exhaust pipe

In the most unsafe places, plugs for cleaning should be installed.

If the sewer system is designed and laid correctly, it will serve you faithfully for many long years.

The drainage mechanism in country houses operates on the principle of gravity. It is clear that for the normal operation of such a system requires a certain angle. If you lay sewer pipes horizontally, then this will not bring the necessary effect, because then there will be no gravity under which water will move by gravity.

Necessary and accurate calculations, because with a small angle not all moisture will leave the house, a certain amount of water will remain in the pipes, which can cause clogging. If you set the angle too sharp, then the solid elements will simply settle on the walls of the pipeline, which will also adversely affect the operation of the system.

Why is it necessary to choose the angle of inclination

Gravity drainage is the most popular type of drainage in rural cottages. To prevent clogging of pipes, and the system worked as long as possible, it is necessary to choose the right angle. As already mentioned, it cannot be too sharp or too small. A very small slope is not recommended for obvious reasons, but a too wide angle brings trouble:

A large angle of inclination leads to a rapid flow of wastewater, solid particles simply do not have time to leave the pipeline and it becomes clogged. At best, cleaning will be required, and at worst, replacing all pipes;
With acute angle and the use of long pipes, a siphon shutter may break. The entire sewer system will be disrupted, and unpleasant odors of sewage will firmly settle in the walls of the house;
Using metal pipes and setting a large angle of inclination leads to the fact that part of the pipe will be filled with water, and the top layer will be filled with air. This will lead to rust and sudden replacement of the pipeline.

In addition to such negative consequences, the work of the drainage system will also be disrupted. At high angles, the system will work very noisily, and bring a lot of inconvenience.

SNiP standards

In SNiP 2.04.01-85, and more precisely in paragraph 18.2 (which governs the installation of drainage devices), such standards are prescribed that must be followed when choosing an angle:

Each linear meter of the pipeline (with a diameter of less than 50 mm) should increase the angle of inclination by 3 centimeters. In the case of large pipes (from 110 mm), the slope increases by 2 centimeters;

The maximum slope of the pipe from its beginning to the end is 15 degrees;
According to the document, when arranging water disposal, it is necessary to take into account the level of freezing of the earth in order to establish the sewer system correctly;
In order not to make a mistake with the choice of the angle of inclination, you need to consult with specialists and calculate data using special formulas;
Installing pipes in the bathroom allows you to equip the coefficient of fullness, and slightly reduce the angle of inclination. This is due to the fact that mainly water comes out of the bathroom, without any other elements;
Before carrying out work, it is necessary to draw up a detailed plan.

How to calculate the angle of inclination

There is a concept - the minimum slope of the sewage system, which will ensure high-quality water flow. There are also formulas that help to calculate this concept in each case. In most situations, there are 2-3 centimeters of slope per 1 meter of pipe (depending on its diameter). Based on such a simple formula, it becomes clear that each meter of the pipe should be 2 centimeters lower than the previous one. A simple example will help to understand the situation, if the drain pipe has a length of 11 meters, then the change in height between its base and the end point will be 22 centimeters.

But this is if we take into account only unpolluted water, and, as you know, there are a lot of solid particles in the effluents, which, with large accumulation, clog pipes. As a result, the drainage system with the wrong angle will have to be cleaned regularly.

It is precisely because of such features of the system that they developed a special item in building codes that regulates the process of sewage equipment in a private house. The angle should be at the design stage of a country cottage or any other room.

It is worth considering that SNiP regulates the measurement of the angle only in centimeters. Many believe that this can be done in degrees, but this is wrong. The slightest measurement error can cause the wastewater system to malfunction. This, in turn, will lead to frequent congestion and pipe cleaning.

Slope of the internal sewage system

If you make the drainage of the internal sewage system, then you need to follow all the standards for the level of the slope of the pipes. For this, during work, it is necessary to fulfill the requirements of SNiP in relation to the ratio of pipe diameter and level of slope.

Pipes with a diameter of 50 mm and 110 are used to equip the internal system. When constructing a sewer system, do not lay pipes at a right angle, for this a sequential fastening with a small angle is used.

In cases where it was not possible to avoid right angles, special cleanings are put on turns. The whole system is attached using clamps, the step of which is calculated by the formula pipe diameter x 10.

Slope of the external sewage system

For the outer part of the sewer, large diameter pipes (110-200 mm) are used. SNiP provides certain requirements for this type of equipment:

At 110 mm, the slope should be 0.03 per meter or more;
At 160 mm, a slope of 0.008 per linear meter;
At 200 mm, a slope of 0.007 per linear meter.

When laying the external part of the system, it is also necessary to follow the rules, as well as when working with the internal system. In the ground, the pipes should be 30 cm lower than the freezing level. If you do not, then you will have to additionally insulate the equipment.

The fact that you have to lay pipes at a certain angle should be remembered even when digging trenches. By the way, trenches should be 20-30 centimeters deeper than the level of pipe laying. If they turned out to be excessively deep, then you need to sprinkle pits with a mixture of earth and sand, and then compact well. To prevent mistakes when digging trenches, twine is pulled at the required level.

The top layer will be ordinary sand, through which the pipeline system will pass. To achieve equipment sealing, the sockets must be installed “facing” the flow.

It is necessary to carefully monitor all the details of the structure, they should not have any defects (cracks, chips, etc.). If we neglect this, then there will be regular flooding of the whole system.