Lifting system backflow plate

One more thing, if

we are just before the building permit application and our developer claims that we are obliged to plan and implement a backflow prevention system.

he really is a developer:

that's _HIS_ problem, not yours! You have bought a piece of house and land at a (hopefully) fixed price. If he has overlooked in the planning that a lifting system is required: HIS bad luck! He must deliver a house that complies with the regulations at the agreed price.

Best regards,

Andreas

Even if the ground floor is 30 cm below street level, the top edge of the toilet is 15-20 cm _ABOVE_ the street and thus above the backflow level.

Nothing can come up from the toilet, unless you have a local black hole with a reversal of all gravitational laws in your bathroom….

This argument is wrong. I find it just as annoying when the crap comes back up from the floor-level shower. When there is too much rain and the flap is closed, everything is then pushed into the shower. Not nice.

Hi,

this here...

I find it just as annoying when the crap comes back out of the floor-level shower. When there is too much rain, everything is pushed into the shower because the flap is closed. Not nice.

... would indeed be unpleasant. But the OP didn’t say anything about a floor-level shower on the ground floor. If there is one, however, it is enough to install a small lifting unit just for the shower, which then costs only 500-1000 € more including installation and all that. It only gets expensive for those who can also pump wastewater containing feces.

Best regards,

Andreas

Even if the ground floor is 30 cm below street level, the top edge of the toilet is therefore 15-20 cm _ABOVE_ the street and thus above the backwater level.

Maybe a floor drain in the utility room?
Also not ideal.

There are also municipalities where backwater valves are not allowed.

But the information from the OP was partly contradictory. A clarification would be necessary here.

Our ground floor is about 30 cm below the last backwater level in the sewer.

I tend to agree with your provider regardless of whether it is 30 or only 20 cm. Incidentally, a lifting system is not for rainwater but for wastewater; so here it concerns your smaller and larger business.

The top edge of the finished floor is below the backwater level, so a lifting system is necessary; as a provider, I would not assume liability if you wanted to build _without_ one, against better knowledge.

Rhenish greetings

Hi,

regardless of the fact that the OP would have to clarify whether the top edge of the finished floor is below or above the backwater level and whether it concerns wastewater or rainwater:

The top edge of the finished floor is below the backwater level, so a lifting station is necessary; as a provider, I would also not assume liability if you, against better knowledge, wanted to build _without_ one.

Now please explain to me how something is supposed to come out at washbasin drains that are at least 50-60 cm and toilet rims at about 50 cm. That is still 20 cm ABOVE the backwater level. A walk-in shower is a special case; for that, a small lifting station would indeed make sense.

In any case, in the event of a sewer overflow, a lifting station would be useless. Then the house just floods through the front door. If the OP's information is correct, at the moment the sewer overflows, a full 20 cm of water stands at the front door. Then you don’t have to worry about the washbasin or any drains anymore!

Best regards,

Andreas