Hello everyone,
We are close to submitting our building permit / planning permission, and our builder claims that we are required to plan and install a backflow prevention system.
We understand this in principle. However, what really isn’t clear to us is why we are not allowed to install a backwater valve for sewage and are allegedly required to install a lifting station (sump pump system).
Here is the situation:
The plot is completely flat, and rainwater is not allowed to be discharged into the sewer system anywhere in the development; it must drain into an infiltration pit. Our ground floor is located approximately 30cm (12 inches) below the last backflow level in the sewer. The property / development is situated on top of a hill, so no water is flowing downhill toward it; in fact, water drains away quickly.
This means that for a rare event that might occur once every five years, when the sewer cannot handle the rainwater, we are supposed to install a lifting station.
In our opinion, a backwater valve would clearly be sufficient in this case, not a lifting station. The lifting station serves a different purpose for us. Furthermore, this system is not allowed to be installed outside the building, so we would have to have a flap and the system under the slab in the utility room.
The whole setup is estimated to cost about 7,000 euros (around $7,700) without any excavation work.
Are we being too simplistic, or is the builder correct?
By the way, for insurance purposes, a backflow prevention device is important. A flap valve alone should be enough and certainly achieve the same effect.
Thank you for your opinions.
We are close to submitting our building permit / planning permission, and our builder claims that we are required to plan and install a backflow prevention system.
We understand this in principle. However, what really isn’t clear to us is why we are not allowed to install a backwater valve for sewage and are allegedly required to install a lifting station (sump pump system).
Here is the situation:
The plot is completely flat, and rainwater is not allowed to be discharged into the sewer system anywhere in the development; it must drain into an infiltration pit. Our ground floor is located approximately 30cm (12 inches) below the last backflow level in the sewer. The property / development is situated on top of a hill, so no water is flowing downhill toward it; in fact, water drains away quickly.
This means that for a rare event that might occur once every five years, when the sewer cannot handle the rainwater, we are supposed to install a lifting station.
In our opinion, a backwater valve would clearly be sufficient in this case, not a lifting station. The lifting station serves a different purpose for us. Furthermore, this system is not allowed to be installed outside the building, so we would have to have a flap and the system under the slab in the utility room.
The whole setup is estimated to cost about 7,000 euros (around $7,700) without any excavation work.
Are we being too simplistic, or is the builder correct?
By the way, for insurance purposes, a backflow prevention device is important. A flap valve alone should be enough and certainly achieve the same effect.
Thank you for your opinions.
One more thing, if
this is really a developer:
that is _HIS_ problem, not yours! You have purchased a house and land at a (hopefully) fixed price. If he has overlooked during the planning that a lifting station is mandatory: HIS bad luck! He must deliver a house that complies with the regulations at the agreed price.
Best regards,
Andreas
loreen1303 schrieb:
we are just about to submit the building permit / planning permission application, and our developer claims that we are required to include and install a backflow prevention system.
this is really a developer:
that is _HIS_ problem, not yours! You have purchased a house and land at a (hopefully) fixed price. If he has overlooked during the planning that a lifting station is mandatory: HIS bad luck! He must deliver a house that complies with the regulations at the agreed price.
Best regards,
Andreas
andimann schrieb:
Even if the ground floor is 30 cm below street level, the top edge of the toilet is still 15-20 cm _ABOVE_ the street and therefore above the backwater level.
Nothing can come up from the toilet unless you have a local black hole reversing all the laws of gravity in your bathroom… This reasoning is incorrect. I find it just as frustrating when sewage backs up through a walk-in shower at floor level. When there is heavy rain and the flap is closed, everything gets pushed back into the shower. Not pleasant.
Hi,
this...
... would indeed be unpleasant. However, the original poster didn’t mention a walk-in shower on the ground floor. If there is one, it’s usually enough to install a small lifting station just for the shower, which with installation and everything else costs only about 500–1000 € more. It only gets expensive if the system also has to handle sewage.
Best regards,
Andreas
this...
Saruss schrieb:
I find it just as annoying when the crap comes back out of a walk-in shower. When there’s too much rain and the valve is closed, everything gets pushed into the shower. Not nice.
... would indeed be unpleasant. However, the original poster didn’t mention a walk-in shower on the ground floor. If there is one, it’s usually enough to install a small lifting station just for the shower, which with installation and everything else costs only about 500–1000 € more. It only gets expensive if the system also has to handle sewage.
Best regards,
Andreas
C
Caspar202020 May 2016 15:21andimann schrieb:
Even if the ground floor is 30cm (12 inches) below street level, the top edge of the toilet is still 15-20cm (6-8 inches) _ABOVE_ the street and thus above the backwater level.Maybe a floor drain in the utility room?
Not ideal either.
There are also municipalities where backwater valves are not allowed.
However, the original poster’s information was partly contradictory. A clarification would be helpful here.
B
Bauexperte20 May 2016 15:50loreen1303 schrieb:
Our ground floor is about 30cm (12 inches) below the latest backflow level in the sewer.I tend to agree with your provider regardless of whether it is 30 or only 20cm (12 or 8 inches). Besides, a lift station (sump pump) is not intended for rainwater but for wastewater; so this concerns your smaller and larger sewage.The finished floor level is below the backflow level, so a lift station is necessary. As a provider, I would also not assume liability if you were to build without one against better advice.
Regards, Bauexperte
Hi,
regardless of whether the original poster needs to clarify if the finished floor level is below or above the backflow level and whether it concerns wastewater or rainwater:
Now can someone please explain to me how anything could flow out of washbasin drains, which are at least 50-60 cm (20-24 inches) and toilet rims at about 50 cm (20 inches) above the backflow level? That is still 20 cm (8 inches) ABOVE the backflow level. A walk-in shower at floor level is a special case, and a small lifting system would indeed make sense there.
In any case, in the event of a sewer overflow, a lifting system would be useless. The house would simply flood through the front door. If the original poster’s information is correct, at the moment the sewer overflows, there would be about 20 cm (8 inches) of water at the front door. You don’t need to worry about washbasin drains or any other outlets then!
Best regards,
Andreas
regardless of whether the original poster needs to clarify if the finished floor level is below or above the backflow level and whether it concerns wastewater or rainwater:
Bauexperte schrieb:
The finished floor level is below the backflow level, so a lifting system is necessary; as a supplier, I would also not take responsibility if you decided to build without one against better advice.
Now can someone please explain to me how anything could flow out of washbasin drains, which are at least 50-60 cm (20-24 inches) and toilet rims at about 50 cm (20 inches) above the backflow level? That is still 20 cm (8 inches) ABOVE the backflow level. A walk-in shower at floor level is a special case, and a small lifting system would indeed make sense there.
In any case, in the event of a sewer overflow, a lifting system would be useless. The house would simply flood through the front door. If the original poster’s information is correct, at the moment the sewer overflows, there would be about 20 cm (8 inches) of water at the front door. You don’t need to worry about washbasin drains or any other outlets then!
Best regards,
Andreas
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