# GPM concerns



## jakemauldin (Mar 26, 2019)

Ok so I have a bit of an issue, I tested my water flow rate and I'm only getting out 10 GPM and that is right at the meter, I have great pressure of 80 PSI. This is coming out of a 3/4" line. The mainline is 8". The flow rate seems really low and after reading what the flow rates of particular sprinklers are makes me wonder if I'll ever be able to run an irrigation system on that. Do you guys have some input on this? I have read hours and hours worth about irrigation and it is still a very confusing topic.


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## unclebucks06 (Apr 25, 2018)

What test method did you use?
You can do a system on 10gpms. Thats what my original system was until I got a well.

I think you wanted to do a large yard though so 10gpms is going to be tough.


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## SCGrassMan (Dec 17, 2017)

Did you test from that 3/4 feed to the house, or from a hose bib?


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## jakemauldin (Mar 26, 2019)

I did it from a hose bib that I stubbed up a foot after the meter. Then I checked it at the house as well. But I used the 5 gallon bucket method


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## g-man (Jun 15, 2017)

3/4 Copper or PEX?


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## unclebucks06 (Apr 25, 2018)

Hose bib is going to restrict a little. Might try a balll valve to see if you can gain a few more gpm.


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## jakemauldin (Mar 26, 2019)

its from a 3/4 tap to 3/4 meter then I ran 1" pex for all supply lines


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## g-man (Jun 15, 2017)

PEX is very restrictive to flow because the internal diameter is small. I have 3/4 PEX to the meter and then from the meter to the house. I designed my system to not exceed 5gpm.

This table used to be in irrigation tutorials.com


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## jakemauldin (Mar 26, 2019)

so I wonder if changing out the Pex to a steel pipe coming off of the meter would help then "Y" off leaving my PEX to the house but continue black pipe to the valves of the irrigation. My thoughts are that my house has decent enough gpm without issues since most appliances don't call for a major rate of flow. Then that would leave me getting the most possible GPM to the irrigation at least. Please correct me if someone thinks I might run into more issues doing it this way.


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## g-man (Jun 15, 2017)

I don think you should use a steel pipe on potable water. If you want to switch, then go to 1in copper. 1in copper from meter and T to the irrigation, then switch it to PEX for the house.


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## jakemauldin (Mar 26, 2019)

@g-man I like how you think. I hope I can get some additional GPM from that. Because I believe they only allow a 1" tap for that 8" main and that's about 1500 extra since they have to bore under the road for it. Not sure I'm ready to do that until I know for sure I'm not going to be able to accomplish my goal with the 3/4" tap I have now. 
That leads me to my next question, Is a flow rate of 10-12 GPM going to leave me with an outrageous number of zones to irrigate 2ish acres?


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## g-man (Jun 15, 2017)

You can leave the 3/4 tap at the main and only change after the meter.

So the first question, do you really want to pay to irrigate 2acres from city water? A well will pay for itself in no time.

To give you some numbers, 1in of water over an acre is 27,154 gallons. If you do just 1in a week for the 2 acres, then that's 217,232 gallons of water.


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## jakemauldin (Mar 26, 2019)

@g-man Well, I don't really want to pay them, It's a little better since we are on a co-op. The rates of our co-op are a little better. A well would be ideal but It will cost me 12k to get a well dug. Our water table is very deep where I live. I don't have 12k to drop on it at the moment; Definitely not prior to Momma getting her pool put in.


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## g-man (Jun 15, 2017)

Ok to finish the calculation. 27,154 gallons at 10gpm = 2715 minutes/acre = 45hrs/acre.

Let's say you target 0.5in, that drops the 45hr to 22hrs. You will then need to break out your lawn and do a section every night (~12hrs) to be able to do the whole 2 acres.


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## SCGrassMan (Dec 17, 2017)

Sometimes, you can just get a larger meter put in, without changing the feed line, and you could Y off the line just past the meter.

In my area, they will also install a second meter for about $800 specifically for your irrigation.

Hope something in that helps or gives you some stuff to explore.

$15k for a well, even a deep well, sounds very steep. Around me they're about 3k with the pump and the whole 9 yards, so maybe check around on that as well?


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