What is the angle of inclination of the sewer pipe in a private house

Construction norms and rules (SNiP) during the installation of the sewage system oblige to take into account the angle of inclination of the pipes in relation to the cesspool or septic tank. The efficiency of the entire system depends on how optimal the angle will be. Too great an inclination of the pipe and a high speed of water prevents the complete washout of solid particles of debris, and the absence of an angle of inclination is a gross violation of building rules, after which solid particles begin to gradually accumulate on the walls and clog the lumen of the pipe.

What is the angle of inclination of the pipeline

The installation of an autonomous sewage system begins with preliminary calculations of the length of the pipeline, the diameter of the pipes and their slope. The speed of the water flow inside and the direction of movement will depend on this. It is especially important to follow the rules if the sewage system is planned to be gravity flow. The gravitational forces will direct the impurities in a natural way to the place of their storage.

The angle of inclination of the sewer pipe in a private house depends on the following indicators:

• Pipe diameter. The larger it is, the smaller the slope.
• The material from which the pipes are made. The smooth inner surface facilitates the rapid passage of water and debris through the drain. Cast iron, asbestos cement and some synthetic materials have a rough surface, which over time adheres to a large layer of sludge. This reduces the performance of the pipe. Even with a large diameter, the throughput decreases, and flooding occurs in the house, if measures for cleaning are not taken in time. The clogged pipe will have to be cleaned regularly, and this is inconvenience, the cost of chemicals and a call to a plumber.
• The layout of the sewer pipe system in the house. A smaller diameter for drains in the bathroom, shower and kitchen implies a greater slope of the pipe.

In addition to the angle of inclination, for the correct operation of the drainage system, it is important that there are no sharp and right angles in the connection of pipe parts and when cornering.

If the rules are not followed, the following problems are possible:

• silting up the pipe and stopping the work of the sewage system, which entails an increase in the water level in the toilet bowl, sink and the occurrence of a problematic drain in the bathroom;
• the appearance of an unpleasant odor in the apartment due to poor operation of the siphons;
• breakthrough of the pipe and flooding of the basement.

Both the minimum and maximum slope are important. The extremes in the calculations lead to the rapid failure of communications - in just a year you can clog the pipes.

Optimal value selection

The slope is calculated not in degrees, but in centimeters, which is much easier to control by pulling the rope straight. When laying 1 m of pipe, it is necessary to tilt it in the direction of the settling well by a certain amount, which depends, first of all, on the diameter and structure of the inner surface.

To determine the slope, experts use special formulas. It is important to calculate the flow rate based on the material and the degree of fullness. It is customary to take 1 (unit) for the maximum indicator of the fullness of the pipe. In this case, the slope is completely absent - the system is installed incorrectly. A 50% filling of the lumen is normal.

The formula for calculating the degree of filling: H (fullness) = B (height of the drains): D (pipe diameter). This needs to be calculated in order to determine the maximum speed at which the masses must move inwardly towards the sump.

To calculate the speed of movement, it is necessary to take into account:

• coefficient (K) of roughness and hydraulic resistance of the flow, which for polymeric materials is 0.5, for all others - 0.6;
• pipe diameter - D;
• height of drains (B) - filling level of the pipe lumen.

The coefficient must be less than or equal to the speed multiplied by the square root of the height of the drains divided by the diameter: K = V (V: D). Theoretically, the speed can be calculated, but in practice the filling of the sewer is always different, therefore it is recommended to adhere to average values, without increasing or decreasing the slope.

The minimum and maximum slope of the sewage system per 1 running meter according to SNiP

In private houses, pipes with a diameter of 50, 110, 150 and 200 mm are installed. A section above 200 mm is used in industrial facilities, for which there are rules.

The slope of the sewage system is 1 meter according to SNiP for each pipe size:

• 50 mm - slope 3 - 3.5 cm per linear meter;
• 100 - 110 mm must be laid with a slope of 2 cm per meter;
• 150 mm - 1 cm;
• 200 mm - 0.5 - 0.8 cm per meter.

Example: the length of a pipe with a diameter of 50 mm is 7 meters before the first turn. For each meter, it is necessary to deepen it by 3 cm. 3X7 = 21 cm. That is, the difference between the upper and lower points should be 21 cm. After turning, the pipe continues to be led downward with a slope. If it passes into a wider part of the highway, then the standards concerning the new section begin to apply, that is, the slope decreases.

If the sewage system is not designed for solid particles, for example, storm sewers, minimum values ​​can be applied, provided that there are sand traps at the entrance to it, which can be cleaned often and not worry about the state of deep communications.

Calculation for an apartment

In apartment buildings, the sewage system is also gravity, so the pipes are laid with an inclination to the main riser. If the height of the plumbing device does not make it possible to make the desired slope, horizontal wiring is used. In this case, a pump is installed, and the sewage system becomes pressure. Pumps are needed with long horizontal lines so that solid particles do not accumulate inside the pipe, which subsequently reduce its performance.

For an apartment, the option of a branched sewage system is suitable, so that each device has its own branch. In this case, it is possible to comply with the slope norms according to SNiP. In older houses, the kitchen and bathtub were connected to the same pipe. Now a tee is installed on the main riser - for a toilet bowl with a diameter of 110 mm, for a bathroom and a kitchen with a diameter of 50 mm.

In order for the apartment system to work without blockages, the following standards must be observed:

• The bathroom, sink, shower and kitchen sink are connected to the central sewerage system using pipes with a diameter of 40 or 50 mm. The minimum slope is 2.5 cm, the maximum is 3.5 cm.
• The toilet is connected with a plastic pipe with a diameter of 100 - 110 mm. The minimum slope is 12 mm per meter, the maximum is 2.5 cm. The norm is 2 cm per linear meter.

When building new houses with a complex sewage system and a large number of household appliances that use water and sewage, the Callbrook-White formula is used, which takes into account the viscosity of the liquid, the degree of roughness of the inner walls, the acceleration of gravity, the average speed of the sewage along the highway, the hydraulic slope and the diameter pipes. The formula is difficult for ordinary people who do not do calculations on a daily basis, so it is better to use simplified diagrams and focus on the pipe diameter.

Calculation for a private house

When installing the sewage system of a private house, preliminary calculations are made so that in the end the pipe filling is at the level of 30%, maximum 50%.For a private house, when installing an external sewage system, pipes of a larger diameter are installed, taking into account the number of drain points - 1 - 2 toilet bowls, 2 - 3 bathrooms or showers, a kitchen, 1 - 2 washing machines. The car wash, which is located in the garage, drains the waste into the general sewer. If there is a bathhouse or sauna with a built-in pool inside, then the diameter of the outer sewer pipe must be at least 200 mm.

For a private house, it is more important to properly equip the internal sewage system in order to remove the drains into the external pipe. It is inside that blockages most often occur. If you are laying pipes yourself, you need to draw the entire line on the walls and mark problem areas so that you can call a specialist and ask for help. If everything matches the drawings, you can proceed with the installation. Before embedding pipes in decorative panels, the drains are checked by timing the time they pass the section of the highway.

An incorrectly equipped exit of the internal highway to an external pipe gives residents many problems.

There are only two errors in the slope of the pipe: its lack or excess. Therefore, it is recommended to be guided by the normative acts of SNiP, which are calculated for each type of material and a certain diameter.

Calculations for outdoor sewerage

The rules for installing external sewerage include:

• Unobstructed outlet of the internal line through the hole in the foundation, which must be larger than the pipe diameter. This is necessary in case shrinkage occurs and concrete structures begin to press on the plastic pipe, which will damage it. A reverse bias may form, which is fraught with stagnation of water and fecal matter in the bathrooms.
• At the outlet, the pipe is placed in a metal sheath and wrapped in foam to reduce the risk of damage and freezing in winter.
• Internal pipes are not intended for laying in the ground, since they have different technical characteristics and are not able to withstand aggressive environmental conditions for a long time.

The laying of the external highway is carried out no higher than 50 cm from the surface of the earth, since communications freeze in winter and it will be necessary to use hydrodynamic machines to remove ice inside. Based on the slope, the trench is made the deeper the closer the pipe comes to the septic tank. The slope of a pipe with a diameter of 110 mm for external sewerage must be at least 1.5 - 2 cm per running meter.

Errors in determining the angle of inclination of pipes

The largest number of blockages and sewer failures are due to improper design. Failure to comply with the rules of SNiP leads to the breakdown of water locks, an unpleasant odor in the room, poor drainage from the sink and bathroom, silting of pipes. A pipe rupture and a sewer spill can lead to contamination of human pathogens, as well as poisoning by toxic fumes.

Installation errors are the incorrectly selected pipe diameter, the lack of a drain pipe and ventilation. As a result - low pressure and difficult passage of viscous masses due to poor air circulation in the system.

In addition to a slope, improper pipe joining angles, lack of seals, incorrect transition of a smaller diameter to a larger one can lead to poor operation of the sewer system.

More problems are caused by improper installation of cast iron pipes, in which sediment forms faster, since they have a rough surface. Stagnation of fluid in one of the areas leads to rotting and leakage of pipes.

Plastic communications are less prone to blockages, but even in them, muddy sediment can accumulate if the system is incorrectly designed - choose the wrong diameter or incorrectly calculate the slope. Non-professional workers often try to increase the slope of the pipes, believing that in this way the wastewater will reach the sump faster.

The use of cheap building materials leads to their rapid failure. High-quality products are checked with special equipment for the presence of hidden cracks, chips, burrs inside. If the manufacturer neglects to check for quality, such products are cheaper, but only the buyer is responsible for them.

It is unreasonable to install powerful purification systems in the place where conditions and soil allow to clean the effluent in a natural way, without harming the environment.

When installing a sewage system in a new building, design and calculations should be carried out by specialized organizations that have engineers on their staff. A license for this type of work is required. It is desirable that the company has experience of work in local climatic conditions, on this type of soil.