Hello, My sprinkler system runs off an irrigation well system with a bladder tank. The well has a 1HP Jet pump that will only pump 8 gpm @ 40-60 psi. As the system runs after 3-4 minutes the pressure will drop to 20 or so psi and the sprinkler heads start to drop. So I'm not getting enough water from the well. What I was considering was to add city water to the system but it also is only 9gph and 35-40 psi to where I can connect from city water. So what I was considering is combining the two to get more gpm and the pump will take care of the pressure which cuts out at 60 psi. This will only be used for the sprinkler system. I have a Watts backflow preventer which I will use to keep the irrigation water out of the city system. I want the well to be used primarily. So will it be all right to do this?
Where should I put the inlet for city water? Before the pump inlet? After the pump, before the bladder tank? After the bladder tank?
I hope you understand what I want to accomplish. Thanks

You should run this idea by a mechanical engineer. I think there is a flaw in your design. I think TORO offers free sprinkler design calculations.

In the interim: to increase GPM you need either: 1. more pressure through existing pipes or 2. upgrade your pipes to larger size

If your volume delivery drops after few minutes than you have either: undersized pipes, too many sprinkler heads on one branch, or small pump.

Thanks for the input Milo. The well used to have a submersible pump. It wasn't working so I took it out and put the jet pump in.
The pipes and lines are all 1" to the sprinkler heads. I think the pump is just not up to par for the system. Previous owner told me pump quit working after only 2 seasons of watering. I think because this is a very sandy area and the sand wasted the pump.
Maybe I'll go back to another submersible. Thanks again.

Or consider installing "booster pump" on your sprinkler system.

I think it's a gpm problem. The zone that is the worst has 10 sprayer heads 1804 Rainbirds. Maybe I'll switch to 4-5 rotors. They go farther and actually have nozzles that use less water per minute. Thanks again

Quote:

---

So what I was considering is combining the two

---

You can't do that! Chapter Twelve, Section 1286.6 Of The Standard Plumbing Code under "Private Water Supply" reads: No private water supply shall be inter-connected with any public water supply.
There are no exceptions to this.
I like Milos idea of adding a booster pump. Regards, tom

Thanks for the heads up speedball1. Looks like I go with a new submersible or a booster. Thanks again.