I have a septic tank in my house in Spain.
All the 110mm PVC toilet soil pipes drain into the tank.
Additionally, there is one 110 mm PVC pipe that collects rain water that also drains into the tank.
This is not good because it interferes with the proper working of the septic tank and it wastes rain water (it also has the added problem of flooding the septic tank)
I am thinking of cutting that rain water pipe, sealing the end that goes to the septic tank and diverting the other end into a water reservoir where the rainfall of all the other roofs of the house is collected.
The problem with this is that I wonder if I will be interfering with the proper ventilation and pressure equalization of the soil pipes and septic tank.
The septic tank needs air, that was provided by that rain pipe. If I seal it, I may stop the septic tank from working properly. If I don't seal it, since the cut will be inside a basement, I wonder if the basement will get bad smell and insects.
Also, since each toilet soil pipe has a water trap, will the soil pipes work properly if the whole system is sealed (i.e. no air entering at any point)
Thanks,
Antonio