Question
Im installing a new sprinkler system.  There had been a previous system
before but it was removed.  The supply goes from 3/4" copper to 1" PVC sch
40 where it is capped off.  I have a 3/4" PVB backflow preventer.  My question
is, can i just continue on with the 1" pvc, and use reducer fitting to connect in
and out of the PVB?  I also have a 3/4" pressure regulator that is the same
question.  I dont see a problem but i could be wrong.  I have about 9-12gpm
and a static water pressure at the source of around 82psi ( which is why i
have the pressure regulator).  I have all the supplies for 1" PVC for the whole
system, so I'm hoping to be able to use it.

Answer
Hey Andrew I hope this helps. You are correct, stay with the 1" pvc mainline and reduce it from the backflow preventer. You will get better volume with the 1" line. You might not have to install the pressure regulator. If you're getting 82psi, this is a good pressure for your system. If it was above 90psi, then you might put it on. Let me know if I can be of anymore help. Thanks and have a great day.