Drainage water lifting system

Drainage water / Drainage DIN 4095

Drainage to protect structures

A drainage system consists of drainage, control and flushing equipment, as well as the drains.

Inspection and flushing manholes should be located at every change of direction of a drainage line and should be equal to or larger than DN 300. The inspection chambers must be arranged in such a way that the drainage can be checked at any time. The planning of a drainage system goes hand in hand with the planning of the building waterproofing.

Three cases are listed in DIN 4095 for deciding whether a drainage line is required.

1. If only soil moisture is present in highly permeable soils (sealing without drainage)
2. If accumulating water can be removed via a drainage system and if it is ensured that there is no water pressure on the building waterproofing. (Waterproofing with drainage)
3. If pressing water is present, usually in the form of groundwater, or if it is not possible to drain the water via a drainage system. (Waterproofing of the building is required here, e.g. watertight tank/basement, without drainage)

When a drainage system is built, it must be constructed at the correct height around a building and have appropriate control options. The specifications for this can be found in DIN 4095.

According to DIN 4095, 8.5, drainage water should run off with a natural gradient or by artificial lifting into a receiving watercourse. Infiltration into the site itself is also possible and desirable. If there is no possibility of infiltration, structural precautions are taken in new buildings to ensure that the parts of the building exposed to drainage water are waterproof. If drainage water seeps into the ground, the soil must be permeable.

Very highly permeable Gravel, gravel soils

Highly permeable Coarse sand, gravel sands

Permeable sands, mixed-grained soils with a high coarse fraction

Weakly permeable loam, mixed-grained soils with a low coarse fraction

Very slightly permeable loam, silty clay

Drainage systems on old houses / existing house systems

Retain? Disconnect? Convert?

This question will be discussed frequently over the next few years.

Drainage systems are often incorrectly connected to the sewer, especially in existing buildings.

The drainage bylaws of cities and municipalities often specify how drainage water is to be handled. If this is not regulated, the relevant authority must be contacted on a case-by-case basis at contact .

Today, we know of building basements in cities that have become waterlogged, where draining into the public sewer has been consistently prohibited. The consistent sealing of sewers through renovation procedures has also led to rising groundwater levels in parts of Germany and has resulted in the basements of old buildings that have been dry for decades now becoming waterlogged. Their masonry lacks the necessary waterproofing and the buildings are also not sealed at the bottom.

What was previously only ground moisture around the cellar can become pressing water in the next few years.

Drainage water may not be able to seep away.

This is the case if the groundwater is very high up against the building or if, for example, the soil survey shows that there is no subsoil capable of infiltration.

An exception can be made in individual cases with the responsible authorities.

In this case, drainage systems must always be connected without backflow.

The following also applies here: backed-up wastewater with a high load on the municipal sewer must not be allowed to enter the drainage system through communicating pipes and thus into the subsoil (groundwater) and possibly contaminate it.

Drainage water lifting systems are accessible shafts, usually DN 1000 mm in diameter. Divided into an inlet area for drainage water and an area for sediment-free, collected drainage water in the pump sump.

A pump can be installed in the pump sump which either feeds backwater-free drainage water to an infiltration system or, possibly after permission has been granted by the authorities, to the public sewer.