Home bathroom and sanitarySewer pipe - important to gradient, diameter and material

Sewer pipe - important to gradient, diameter and material

  • Worth knowing about the sewer
    • Type of sewage
    • Material of sewage pipes
      • HT-tube
      • KG pipe
      • Stoneware pipes
      • 2.4. PE pipe
      • 2.5. More drainpipes
    • Diameter and capacity of sewer pipes
    • Minimum gradient of the lines
    • 5. Ventilation of sewage systems
    • 6. Obligation to leak test

The sewer often plays a subordinate role in house building or renovation. But the sewer pipe and pipes are crucial to the condition and comfort of a home. In addition to the right pipes, a sufficiently large gradient and the diameter of the pipes play important roles in wastewater disposal.

Usually in this country a separate discharge of regular wastewater and rainwater is required. For example, the demands placed on the pipes differ because, for example, domestic waste water can have high temperatures that the wastewater pipe must endure for a long time. There are many different regulations and regulations that you must take into account when constructing the wastewater treatment plant. How big the gradient of a sewer pipe should be and which materials are suitable for the underground piping, we show here in our overview. Here you can also see the diameter of the sewer pipes.

Worth knowing about the sewer

This section gives you an overview of the terms, dimensions and prices of sewers.

Type of sewage

Wastewater is sometimes differentiated into real wastewater and rainwater. In a so-called mixing process, there is a sewer in the community, which receives both wastewater and rainwater. In other municipalities and cities, the rainwater is derived separately from the wastewater, then it is the separation process.

Of course, depending on whether your municipality uses the separation process or the mixing process, you must also separate your wastewater separately from the rainwater. If you use a private wastewater treatment plant, you have no choice but to separate the wastewater from the rainwater anyway.

If your municipality uses the separation process or you have your own wastewater treatment plant, the rainwater must be removed separately. If the house or land is not connected to the public sewage system, the rainwater is led into a sewage ditch. Here too, however, attention must be paid to a sufficient minimum gradient.

Tip: As the owner of a small wastewater treatment plant, you should be very careful that your rainwater can not run into the system. As soon as larger amounts of rainwater overload the system, it can not work properly and the dirty water would run unclear. This automatically invalidates the operating permit of your small wastewater treatment plant. The costs of this regulatory offense are usually painfully high.

Material of sewage pipes

Depending on the purpose of the sewer, different materials are used for the piping. Inside buildings, for example, special heat-resistant HT pipes are necessary. The right piping should always be used in the right place to allow the sewer system to withstand the stresses. KG pipes are more stable than HT pipes and are therefore used outdoors.


The HT pipes are recognizable by their special gray color. Thus, the HT tubes visually set themselves apart from the orange KG tubes. The abbreviation HT stands for these pipes for heat-resistant. Therefore, the HT pipes are laid inside buildings as sewer pipes. Here it is important that the sewage pipes are not only resistant to chemicals and coarse dirt, but also to heat.

Cost of HT pipe
The individual pipes, branches and connectors may not cost the world. But the whole assortment that you need for a single-family home adds up to the costs.

  • Branch 45 ° - Connector for two HT pipes on one HT pipe - DN 40 - about 1, 70 Euro
  • Branch 87 ° - Connector for two HT pipes on one HT pipe - DN 40 - about 1, 70 Euro
  • Reduction - HT pipe reduction in normal design - about 1.30 euros
  • Reduction short - HT pipe reduction in a short design - about 1.50 euros
  • Siphon bends for the wall connection of sinks - about 2.00 Euro
  • Pipe - sewage pipes for the interior - DN 50 - 1 m - about 2.50 euros
  • Cleaning pipe - cleaning access for HT pipe system - DN 50 - 1 m - about 3, 80 Euro
  • Cleaning pipe - Cleaning access for HT pipe system - DN 100 - 1 m - about 4.00 Euro

KG pipe

The orange KG pipe is usually made of sturdy PVC. It is installed outside the house because of its high stability and resistance as a baseline for the sewer system. Meanwhile, there is still a green variant of KG pipes. This is called channel base pipe 2000 or KG2000 pipe. This variant is even more stable than the orange KG tube. but is also used only outdoors, where it does not depend on the heat resistance. However, the green KG2000 pipe raises about twice the cost of the KG pipe.

Cost KG tube

KG pipes are sewer pipes available for installation in the ground and in different diameters:

  • DN 100 - 0.5 meters - about 1.50 euros
  • DN 200 - 0.5 meters - about 6.50 euros
  • DN 315 - 1 meter - about 32, 00 Euro
  • DN 400 - 1 meter - about 50, 00 Euro
  • KG cleaning pipe - DN 100 - 1 meter - about 15, 00 Euro

Stoneware pipes

In the past, only stoneware pipes were used for wastewater. Since they are considerably more expensive and heavier than the KG pipes mentioned above, the pipes made of stoneware are hardly used in a private setting. However, the stoneware pipes are particularly resilient in static terms. Therefore, they are often used in public spaces under roads, for example.

2.4. PE pipe

PE pipes can be installed both inside and outside buildings. The PE pipes are usually black and often somewhat more flexible than the other types of pipes for wastewater discharge. Therefore, PE pipes are often used in garden sheds and arbors to dispose of the wastewater.

2.5. More drainpipes

  • Stainless steel pipe - compatible with plastic pipes - suitable for indoor and outdoor installation - but expensive
  • Concrete pipe - ground line in the outer area - armored and unarmed variants available - very favorable
  • GJS pipe - brown - Pressure pipe for service water disposal - Cement mortar lining with galvanized casing
  • SML pipe - reddish coated - sanitation in the building - material gray cast iron
  • GRP pipe - sanitation / chemicals - material fiberglass and plastic

Diameter and capacity of sewer pipes

The diameter of the sewer pipes is designated DN. For example, in a blueprint, a pipe with a diameter of ten centimeters is called DN10. Underground pipes according to DIN 1986-100 should have at least 10, better 15 cm in diameter.

The diameter of the main or sewer pipe must be additionally adapted to the number of occupants of a building. In a multiple dwelling, either a much stronger pipeline may be required, or corresponding additional sewage pipes may need to be installed. In addition, as few underground lines as possible should run underneath the building itself. The better option is to use manifolds, as they can be more easily remediated later if damage occurs.

Minimum gradient of the lines

The minimum slope that must be maintained on a manifold is 0.5 centimeters per meter of laid pipe. However, if the pipe is not ventilated, the slope must be even 1 cm per meter of laid pipe. On the property, however, you should leave the calculation of the lines to a specialist. The pipework of the sewage system must be laid at least 80 cm deep in the ground so that no frost can damage or freeze the pipes. This is hard to afford for a layman.

5. Ventilation of sewage systems

Venting the sewage system is not just about removing odors. Much more important for the function of the sewer, is the pressure equalization in the system. All waste water downpipes must be provided with ventilation. These must be DIN compliant according to DIN EN 12056 . In addition, the DIN 1986-100 for drainage systems for buildings and land in the execution of the vent must be considered.

  • Venting ensures pressure equalization in the sewer line
  • Good ventilation can reduce the minimum gradient
  • Odors and gases are discharged through the vent pipes
  • DIN-compliant design important

6. Obligation to leak test

As of the beginning of 2016, every property owner must ensure the tightness of his sewers. There is even an obligation to provide proof of a tightness test. According to DIN 1986-30, the owner of a property automatically counts as the operator of his own wastewater treatment plant. He is therefore solely responsible for their proper operation. Most landowners do not know anything about this rule. The leak proof must be renewed later every 20 years, the cost of which is borne by the landowner.

  • since 2016 Tightness test for sewers mandatory
  • Costs are to landowners
  • Leak proof must be renewed after 20 years at the latest
  • The tightness test must be carried out by a certified specialist
  • Subsequently, a renovation of the pipes is often necessary

Tips for quick readers

  • separate wastewater types - rainwater and real wastewater
  • Do not introduce rainwater into small sewage treatment plants
  • only a few underground lines under a building
  • if possible, use a manifold for merging
  • Apartment buildings require several sewage collection lines
  • or large diameter sewer
  • Minimum gradient of the lines must be maintained
  • Slope different for ventilated and unventilated lines
  • Diameter of the pipes
  • Sewer pipe - HT or KG for separate wastewater types
  • Ventilation of sewage systems DIN-compliant
  • Ensure pressure equalization by venting
  • Gases and odors are removed via vent pipe
  • Proof of leakage test since 2016 mandatory
  • Proof must be renewed after 20 years

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