I am installing a medium pressure mister system. I will be tying into the hose bib supply. I will remove the hose bib and install a tee to tap off of. My neighbor had this same system installed and I'm not sure what the plumber did. I attached a photo to see if anybody could explain this setup to me. Just not sure what the purpose of this setup is. I was just going to add a tee and shutoff valve for the water feed to the pump.
Thanks in advance for any help.
Don

That is a testable back flow prevention device known as an atmospheric vacuum breaker the “hose bib” is really the winterization drain

Do I need this setup? Or can I just replace the hose bib and add a tee and shut off for the mister supply line?
We don't freeze here in Phoenix as long as I insulate the exposed pipes.

I assume that is for irrigation purposes your mister can be added with a T but will not have backflow protection
As for whether you need the backflow prevention, vacuum breaker, will be up to your local township codes or water provider

If it were me, I would put a tee after the back flow preventer, which would be the top pipe and add your mister connection there



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Thank you



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Can I get by with just the back flow preventer? Or do I also need the vacuum breaker?

It is the same thing

The device in your picture is known as an atmospheric vacuum breaker which is a type of backflow preventer