ᐅ Installation issues with the pressure hose from the rainwater cistern to the domestic water system

We have one cistern and a domestic water supply system for each semi-detached house. The problem with the pipe penetration through the slab in the utility room is that the concrete contractor installed it too deep and also used 90° bends. Since the ground will still be filled in (which the concrete contractor knew), embedding the penetrations that deep was actually unnecessary. But now that it’s done, it is as it is. We also didn’t pay enough attention or provide detailed instructions. I’m sure it will be better with the next house. 😉

The problem now: The standard 1-inch (2.5cm) pressure hoses are so rigid and inflexible that we probably won’t be able to pass them through the penetration without extensive excavation. We first need to dig a roughly 50–60cm (20–24 inches) deep hole in the gravel and then guide the hose up 1 meter (3 feet) through a 90° bend inside a DN100 (4 inch) sewer pipe.

Are there more flexible pressure hoses available that are still suitable for a suction line with a total length of about 15–20 meters (50–65 feet)?
Direct product recommendations including name and type would be very welcome 😎. I couldn’t find anything suitable at the building supply store or hardware store, and with online products, I can’t check their flexibility firsthand 🙄.

Best regards
Burkhard