Here is the situation. I have a job that we were told that the service line was 1 1/4" but turns out to be 1" poly which changes everything. Heres why: service line 1" poly 550' long from street. 5/8 meter Delivery line 3/4" 3/4" dual check static pressure is 45psi with regulator. belived to be 55 wide open. Heres my question. I would like to run safely from 5-10 gpm. I know that I can do about 4-5 but it would be marginal. The calculations I did tell me that at 12 gpm I would get a wooping 21 psi. How would you go on this one? its a 45 head system at aprox 30' spacing. I'm considering adding a pump to the system to insure its right but would like to avoid. I'm worried that either way I will be restricted because of the 550' poly service line. Any advice is welcome. This is a bit diferrent than what I've incountered so far. Thank you in advance.