We are buying a house that will be delivered in a couple of months. This house is new construction, next to 5 other houses with new sewer and stormwater utilities. And our surprise was that the first floor terrace drain, which is about 50 m², is built into the wall but faces the courtyard, which gives the two rooms a free fall of about 40 cm from the floor, so that the water goes into the courtyard drain. This patio, which will have to divert the water collected by the drainage system, plus the water from the terrace above, will be doomed to not be able to take advantage of this fact. My question is, can I oblige them to take this drainage out into the general drainage system of the house?
As far as I know, there are no rules regarding the drainage of rainwater inside the house.
However, it is important to remember that runoff and rainwater should be separated inside the house so that it drains independently to the outside.
Most importantly, a second drain or overflow should be provided in case the existing drain does not work properly.