Backflow pump - Does such a pump take up a lot of space?

Hello everyone,

we are building a single-family house and are in the middle of the planning phase, shortly before completing the floor plan and preparing the final building application. Our planner has now brought the following to our attention:

"Due to the elevation of the sewage shaft (MW, D 508.90, S 505.68 See LP)
in the street, for safety reasons we had to plan a sewage pumping system as
backflow protection."

We are now wondering what (MW, D 508.90, S 505.68 See LP) means? Presumably, these are elevation indications?! But what does D mean and what does S mean? Attached is our site plan. Is this backflow pump really necessary? Since it naturally involves additional (unplanned) costs and surely also causes maintenance and operating costs, we would really like to avoid such a pump. Are there alternatives to such a pump? Does such a pump take up a lot of space? And what does something like this cost?

Thanks in advance for your help!

Best regards
The Klödis

Hello,

MW means mixed water, meaning sewage and rainwater are discharged in one channel.

D = cover of the channel/manhole
S = brine of the channel/manhole

Are you building with a basement?

Regards
Urmel

Hello,

usually the elevation level of the channel directly in front of your house is considered. D=508.9 means that the manhole cover of the channel is at 508.9 m above sea level, and in the worst-case scenario the wastewater could back up to that height. If you have drains, toilets, showers, etc. in your house below this level, the house would flood without additional protection when the channel fills up.

You can install simple backflow valves, which theoretically is enough. But if they get stuck (ask yourself: will you really dismantle and clean these things every 6 months?), you have a problem...

I assume you are building with a basement. Then wastewater pipes for the drains in the basement will possibly be below 509.9 m. The wastewater pipes for the ground floor and upper floor are then routed separately out of the house; they are higher, so nothing will happen there.

Then as a safe solution you need a lifting system for everything that occurs in the basement. If you have a toilet there, it gets ugly; otherwise, such a small lifting system is not a big deal. Space requirement about like a crate of beer and costs depending on the model 300-800 €.

Best regards,

Andreas