I’m not sure if this is the right category to post this so here goes. Long story short I am getting ready to install my backflow preventer, Zurn 34-720A Wilkins Pressure Vacuum, on my DIY irrigation system. The main water supply is the pipe coming out from under the storage shed. It tees off to the left for the water hose bib and the irrigation is on the right. The other two PVC pipes in the pictures go out to the yard irrigation. The second picture is a mockup of my plan. My question is should I move the water hose bib to the down leg (the outlet side) of the backflow preventer as demonstrated in the third picture? That way the water hose bib will be protected by the backflow preventer and the backflow will be installed 12 inches above the hose bib. You’ll have to excuse the bad photoshop lol I attached pictures.
[https://s33.postimg.cc/oggq467bz/IMG_6805.jpg]
https://s15.postimg.cc/yehcfdbcr/IMG_6814.jpg
https://s15.postimg.cc/exwmsgy4r/IMG_6814newnewnew.jpg
A hose bib is usually essential to have after any type of PVB or backflow device since the hosebib is also susceptible to having contaminants flow back into the potable water system.
Some of the Home centers sell a vacuum breaker that goes directly on the hose big just for that purpose.
Many cities, counties and states require some kind of protection. You can watch so many horror stories on systems that have no backflow protection and it would gross you out since it not only stops chemicals but also waterborne parasites.
Furthermore, a hose bib after any protection device will allow you to measure the pressure in the line which can give you an indication as to device failure further down the line as well as assist you with your irrigation distribution calculations based on your true working pressure.