Backflow preventers for installation within a building

Protection against backwater and water in the cellar

It happens again and again: during heavy thunderstorms or heavy rainfall, the sewer cannot drain the enormous amount of water quickly enough. The water is pushed back from the sewer into homes or commercial buildings, and often floods areas in cellars and basements. This causes considerable damage, resulting in high costs and, last but not least, a lot of annoyance . And yet it is not difficult to solve. A backflow preventer prevents water from the sewer from entering the building. Different types of protections are available for different circumstances and requirements . 

What is backwater?

The term “backwater” describes a phenomenon in which more water temporarily ends up in the sewer than the sewer can process. This can happen, for example, during heavy rainfall or a flood (sewer blockage). The wastewater then begins to rise within the sewer and comes out wherever it can, such as sewer drains and in the worst case, into the drains, sinks and toilets in your basement.

Protection against backwater

Drainage system without backwater protection:

With very high rainfall, the water level rises above the so-called return level. This is usually the height of the road surface. Lower areas in basements and cellars can quickly flood. This leads to significant damage and costs .

Drainage system with backwater protection:

The waste water, which flows via the free fall to the sewer, is protected by a backflow preventer. When backflow occurs, the valve is closed so that waste water can no longer enter the house. If the public sewer is higher than the drainage points in the building, the waste water must be pumped through a lifting station above the backwater level.

What factors should you take into account when choosing a product?

In order to choose the right backwater preventer, a few questions must first be answered. We have summarized these questions below.


1. What type of wastewater needs to be disposed of

Whether it concerns the discharge of faecal-containing or faecal-free waste water, influences the functioning and reliability of the backwater protection. Therefore, before choosing a product, you should ask yourself which plumbing fixtures should be drained through the product. The decisive factor is always the type of waste water that flows in the flow direction via the backwater preventer to the sewer. 

If feces are supplied from urinals or toilets via the connected pipes in the flow direction, this is waste water containing feces.

Faecal-free wastewater is water without faeces, such as wastewater from showers and washing machines.


2. Where should it be installed?

A renovation, stylishly integrated into new construction, installed inside the building or outside the building in a house connection shaft: depending on the local situation, backflow preventers can be installed in different places. You can easily choose the right solution for your situation from the available variants.

Free-standing installation

The cheap, clean and standard-compliant solution for retrofitting backwater systems: ideal for the renovation of old buildings at risk. To avoid having to re-lay all wastewater pipes, which would entail extensive construction work, the central backwater protection can be installed in the existing exposed wastewater pipe. This makes the backwater system easily accessible for maintenance and cleaning of the pipes.

Floor installation

This practical and attractive variant for new buildings provides extra space in basements for toilets, showers or laundry facilities. The backwater system is hidden in the floor. The set can be easily installed and the cover can be tiled as desired, which offers scope for different interior styles and living trends. Whether it will be a music room, home office or wellness oasis.

Earth installation for the building

Until now, products for protection against inflowing water have mainly been installed inside buildings. Very new paths are now being explored. For this purpose, a house connection shaft with integrated backwater protection is placed in front of the building. Depending on the type of waste water (black or gray water), a backwater system can be retrofitted at any time, for example if the basement is given a different function. This way, clients and operators can always err on the side of caution.


3. Is there a drain to the sewer?

When choosing the right backwater protection, not only the type of wastewater and the installation location are important, but it is also important to check whether there is a gradient between the wastewater pipes and the public sewer.

Decay into the sewer

If the sewer is lower than the backwater protection, the domestic wastewater is discharged via the natural gradient. Backwater preventers and hybrid lifting stations can be used here.

No descent to the sewer

If the sewer is higher than the backwater protection, the wastewater must be pumped to the sewer via a backwater loop using a lifting station.


4. How many drainage points are there?

Should they be protected separately or rather centrally in the collection pipe? The best drainage strategy to choose depends on the number of drainage points placed below the backwater level.

Protection of individual drain points

Each drainage point, such as a sink, shower or washing machine, is protected with its own backwater protection.

Central protection

Backflow preventers or lifting stations integrated in the collection pipe protect all connected discharge points.


5. Should it also be possible to drain wastewater during backwater?

If the backflow preventer is closed, no waste water can be discharged from the basement. If that is a problem, you should choose a product that can also drain wastewater without restrictions during backwater.

Protects against backflow

The backwater valve prevents sewage from entering the house.

Drains during backwater

Despite backflow from the sewer and a closed valve, domestic waste water can be discharged via a pump. This way the drainage system can continue to work.

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