ᐅ Electric backflow preventer for toilets located below backwater level?

Hello everyone,

Our ground floor is located below the backwater level. However, there is sufficient slope from our house’s wastewater pipe to the street sewer. Is it allowed to drain with an electric backwater valve and slope? Or do we necessarily have to use a lifting station to pump above the backwater level?

I am aware of the standard DIN EN 12056, which states that this is only permitted for rooms with secondary use. The question is, when does this standard have to be applied? We live in Hamburg. Is compliance with this standard mandatory there? Or is it required nationwide?

Thanks for your help
wagib

To my knowledge, there are also electric backwater valves with built-in pumps, such as the Pumpfix from Kessel. In the event of backflow, these pump the wastewater against the backflow. In that case, a lifting station would no longer be necessary.

We would need this in case we create a basement apartment, so that the toilets can still be used during a backflow situation.

Why would you want to pump even more sewage into an already overloaded sewer system in case of backflow?

Because it’s mandatory. ;-) It happens anyway with everyone who lives above the backwater level. It is even required according to the standard I mentioned that this capability is in place.

@Uwe82:
I took a look at the Pumpfix. It also has an official building authority approval from DIBt, which states: "The installation must comply with the conditions of DIN EN 12056-4. Deviations from the above-mentioned standard, section 4, last paragraph, must not lead to the connected drainage points of the backwater pump system being unusable." This essentially means that the system pumps against the backwater.

However, DIN EN 12056-4 specifies in this paragraph:
"A backwater valve can be used if
- there is a fall towards the sewer,
- the rooms are of secondary use, i.e., no significant valuables or the health of the occupants are at risk in case of flooding,
- the user group is small and has access to a toilet located above the backwater level,
- the drainage point can be taken out of use during backwater."

This means the room must still be of secondary use, the number of users must be small, and a toilet above the backwater level must be available. Unfortunately, this does not apply to my situation.

Deviating from this standard, it is still ensured that the toilets can be used. The standard probably does not yet consider the Pumpfix. Of course, I do not know how it would look in this case 😉