Is it ok to use galvanized pipe for the water supply?
My friend had his house in Florida repiped with PEX and they replaced the backflow preventer. It seemed odd that they used galvanized pipe.
To me it seems like the correct choice, especially since it is in an outdoor location.
Since I'm not an expert, I'd recommend waiting for other professional's comments.
The galvi is on the irrigation side of the back flow device you should see an arrow pointing that way ,I think over a period of time like any galvi it's gonna corrode and close up the did it for stability, how long that takes is a big guess