Do individual irrigation system branch pipes need backflow preventers?

Question

I have an inground sprinkler system with 3 zones.

The water line coming up from the basement is going to the valves and has a Wilkins backflow preventer on it. I am adding 2 new valves/zones for drip irrigation. According to my research, I need to put a backflow preventer on those 2 new zones.

My question is, if I have one on the main waterline feeding the zones do I really need to put 2 more on the 2 new zones? The backflow preventer gets screwed on to the valve followed by a water filter and then a pressure reducer.

Answer 1

The instructions probably state the need for backflow prevention assuming there is none existing. ( probably legally motivated)

If you have backflow prevention on the main line to the system manifold or line to the valves then you do not need any other backflow prevention.