Millions of German homeowners and builders are threatened by backwater damage – they just haven't realised yet. There has never been as much damage caused by flooding and backwater as in the past few years. And yet many house builders and homeowners still don't know that they can and even must protect their property effectively against backwater. These days, local authorities and insurance companies require such protection. Not enough enlightenment and consultation is provided by experienced specialists. The current changes in climate – sudden torrential rain, especially in the summer months – make it vital to draw people's attention to the subject of backwater protection. Professional and suitable draining of both plot and building also contribute maintaining the value of the property in the long term.

BACKWATER - an explosive subject

Heavy rainfalls are increasing

The problem of backwater has always existed. Because for economic and technical reasons, sewage pipes are designed for average rainfall. This means the mixed wastewater pipe can fill up very quickly in the event of a cloudburst.

What's new is the fact that meteorological experts agree: there will be more and more heavy rainfalls in future. The reason: Global warming leads to more evaporation from the earth's surface. This fills rain clouds which then discharge torrential rain.

Local authorities are not liable

Local authorities are not liable for water damage caused after a so-called once-in-a-hundred-years flood. This decision was taken by the Federal Court of Justice in May 2004. According to this latest judgement, local authorities are not liable for damage caused by sewage systems flooding in the event of force majeure. For the first time, the judges in Karlsruhe also defined when exactly heavy rain is to be classified as force majeure: "In the case of unusually heavy rain that only occurs about every 100 years."

Caution: Local authorities are playing safe and ordering plot owners that they have to protect themselves against backwater.

BACKWATER PROTECTION - What you need to know

Problem:

During heavy rain, the water level rises above the so-called backwater level. This term is usually used to mean street level. Rooms in the basement or cellar quickly become flooded. The result: Damage caused by ruined flooring, furniture or electric appliances, soaked household goods and a great deal of hassle and costs for those living in the house.

Solution:

Draining systems such as floor drains, washing machines, sinks, showers (grey water) or toilets (black water), which are below the backwater level have to be protected effectively and permanently against backwater. Wastewater that flows through gravity fed pipes into the sewage system have to be protected by a backwater valve. If the public sewage pipe is higher than the drainage spot, the wastewater must be pumped upwards via a fully automatic lifting station.

BACKWATER is always possible

For economic reasons, public mixed and rainwater pipes cannot be dimensioned in such a way that they can deal with extremely heavy rain without any problems. For this reason, flooding of the sewage pipes and backwater in all connected pipes must be expected in heavy rain.

Other reasons for backwater can be:

Blockage, burst pipes or damage to the sewage system.
Pump failure, if the drainage system is connected to a pumping station.
High water levels in the recipient (stream or river).
Pipe blockage or diversion due to repair work.
Increased wastewater feed, for example when sewage systems are being rinsed, the fire brigage is in action or more pipes are connected to the sewage system than originally planned.

Safe protection through backwater valves

According to DIN EN 12056, backwater protection is to be provided by wastewater lifting stations. Alternatively, backwater valves can be used. The application requirements according to DIN EN 12056-4 are:

There has to be a gradient to the sewage pipe.
The rooms must be rooms of low-priority use.
This means that in the event of backwater, no great material damage may occur or the health of the inhabitants be impaired.
The number of users must be small.
There has to be another toilet available above the backwater level.
In the event of backwater, it must be possible to do without the draining point.

Specification of the constructional conditions

The main selection and application criteria for backwater protection systems depend on several different factors. In particular, the operator's wishes, the object to be drained, the position of the sewage pipe, type of wastewater and respective norm requirements must all be taken into account.

First of all, it has to be decided whether the backwater valve for interior or exterior installation is to be used.

: Backwater protection within buildings

: Backwater protection outside buildings

Which Staufix ® do you need ?

Depending on the type of installation there are various KESSEL backwater
products to choose from. Check your country's EN 13564 backwater
valve requirements for what type of valve is certified for use in your
situation. In the case that this information is not available in your area,
please contact KESSEL directly and we will glad to recommend a product
best matching your needs. KESSEL offers a complete line of fully
certified backwater valves from Type 0 thru Type 5.

For in-line wastwater pipes
Type 0 KESSEL Staufix ® 71... Series
Type 1 KESSEL Staufix ® 72... and Eurofix-Clausio ®
Type 2 KESSEL Staufix ® 73... and SWA
Type 3 KESSEL Staufix ® FKA, Pumpfix ® F

For floor drains
Type 4 KESSEL Single flap floor drains
Type 5 KESSEL Pumpfix ® S, Drehfix ®, Universal, Volatile liquid traps

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