View Full Version : Increase GPM Possible?

06-16-2007, 12:18 AM

I'm new to this site and have a question for the pros. We measured today the PSI and GPM at our house. We were thinking about having a sprinkler system installed, but after today, we're thinking it's not possible. Our static PSI is 86, but our GPM at 40 PSI is only 3.75. It took 1 minute and 20 seconds to fill a 5-gallon bucket at 40 PSI. Isn't that too little to be able to have a sprinkler system installed? We tested again at 50 PSI and it took 2 minutes and 50 seconds to fill a 2-gallon bucket, which meant .705 GPM. Is there anything that can be done to raise the GPM? We're on city water, not a well, and there's nothing on our system that's regulating the water on our side of the meter that we can find.

Any information is helpful, even if the answer is that we're stuck and there's nothing we can do.


06-16-2007, 01:41 PM
Where did you do your bucket test? That flow seems awfully low for a city system.

With a static of 86 psi, how did you adjust the pressure for your flow test?

Try it again, without messing with the pressure. Use the faucet or hose bib that is absolutely the closest to your meter. If you have a draincock on your pressure regulator at the water entrance, that is a great place to check it.

06-16-2007, 09:14 PM
We did the bucket test at the outside faucet closest to the water main. First we put the gauge on the outside faucet in the back and looked at the PSI, which was 86. Then we turned on the outside faucet closest to the water main. We adjusted that until the other outside faucet in the back had the gauge PSI reading of 40. Next we put a bucket under the outside faucet closest to the water main and timed how long it took to fill a 5-gallon bucket.

Are you saying we should do the test on the outside faucet closest to the water main without having the other faucet turned on to make the PSI reading 40? We don't have a pressure regulator at all. We basically found some directions that told us to put a gauge on a faucet outside and then turn on the faucet closest to the water main. Adjust that faucet until the gauge read 40 PSI, and then fill a bucket from the faucet closest to the water main. That's the instructions we followed.

We've found that when we run two or more sprinklers at the same time, there's practically no flow of water inside the house.


06-17-2007, 10:40 AM
That's a pretty severe test. Try the bucket again with the other valve closed.

Doing it the way you did, you should have caught and measured both open valves.

I would be amazed if you don't have a pressure regulator on your entrance. Not saying you're wrong, but it is pretty standard. Should be the first thing in the house where your line comes in from the street.

Bottom line, I think you're in better shape than you think. Get a static pressure reading and a GPM from one single open faucet.

Better yet, get a reputable irrigation firm to come out, analyze your situation and give you a bid on a system.


Sorry, just re-read your reply. I understand what you did now, and it may be somewhat valid, but try your GPM bucket test again with the valve wide open, paying no attention to pressure. Observationally, it might be interesting to note what the pressure is when the valve is wide open. But, don't tweak the valve to achieve a pressure. Just open it up and see how long it takes to get five gallons.