ᐅ Slightly below finished road level, is backflow protection necessary?

Hello,

the planner for our house does not consider a backflow preventer or similar device necessary and has not included anything like that in the drainage planning. The reasoning was roughly that if the plan is approved as it is, we wouldn’t need one.

We are complete beginners and would like to hear several opinions.

The finished floor level will be 5 cm (2 inches) above the “reference height point” shown in the attached drawing (drainage planning drawing). However, the fully developed street will be somewhere between 5 and 15 cm (2 to 6 inches) higher than the construction road.

We have a toilet and a shower on the ground floor.

Thank you in advance...

Hello

All wastewater lines located below the backwater level must be drained using a lifting system.
For example, if a walk-in shower is situated below the street’s drain cover, a lifting station is required. A backwater valve alone is not sufficient.

Olli

Thank you!

We are now having another check to see if the house can be built a bit higher after all. The building notification / building permit application has already been submitted (and is practically approved). Let’s see if this causes any issues...