Water pipeline for water backfeeding and irrigation

Your garden landscaper has no idea. Sure, 32mm means less loss, but the number of sprinklers in the circle depends on consumption. The 12 sprinklers should work with 1.8 m3/h and your pump capacity. What does laid in a ring mean? Hopefully not really a ring. That would be hydraulically bad.

Yes, then he probably has less experience with irrigation or always plans everything conservatively. I agree with you. Then I'll leave everything as it is. It was said to be planned as a ring main which supplies the sprinklers evenly with pressure and water. So from the valve for the sprinkler circuit, all sprinklers are connected in the ring. Maybe I also misunderstood something?

One always talks about a sprinkler circle/ring. However, the pipe should not form a ring because this is hydraulically poor. It still works though. A more even distribution along the pipe is better. With pressure-compensated housings, it no longer plays a big role.

Yes, okay. So I start with circle 1 and the line runs in series through to sprinkler 12. The line ends there too?

Better is central supply and then 6 sprinklers on each side.

Thank you, very good tip. I can also manage to divide exactly on the left and right into 6 sprinklers each.