Cistern always empty despite rain

So, we have now poured water directly into the downpipes. Not a drop reaches the cistern. It should come out under the lid on the right and left. I will have to call the architect today.

Constipation? Are there any grids or inspection openings anywhere at the inlet?

Somehow your water kind of escapes somewhere, what happens if you pour a lot in, basically with a hose? Does it back up and overflow?

Would you like to take a photo of the downpipe?

To my knowledge, there are "switches" that can be installed in the downpipe to direct the water either into the sewage system or alternatively into a cistern. Maybe it's just a simple handle?

A silly question: Have they already connected the rainwater pipes to the [cistern]? Not that they were accidentally connected to the wastewater... €: OK, then there wouldn't be any water in it at all...

So all the gutters lead into the cistern. When you pour water in, you can hear it in the pipe. They are combined in front of the house, then a pipe runs into the cistern under the parking space. The filter is clean, the leaf catcher baskets as well. You are right, the water is going somewhere. The architect will inform the company and then everything will probably have to be checked, if necessary by camera inspection. It remains exciting. Thanks for the help!