# Irrigation GPM and PSI



## mnikon (Jun 7, 2018)

Hello all! I am new to the forum here but have been following for quite some time. I am currently in the process of updating my existing irrigation system from Hunter PGP ultra rotors to MP rotators. The main issue I seem to be having is system pressure. I have read through quite a bit of the irrigation tutorials website but still can't seem to figure out my issue. My home provides 11gpm @ 50psi. However every single rotor zone seems to only operate @ 20psi. While 20psi is low for the MP rotators the 3000s seem to work fine in the front lawn where my heads are only spaced @ 20ft. I am however 2nd guessing the swap in my backyard as the heads are spaced closer to 25-30ft. My main question is what in the world could be eating up 30psi from the source to the heads? I would prefer to operate these at their recommended 40psi. Any help would be greatly appreciated!


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## mnikon (Jun 7, 2018)

A few more notes i forgot to mention. From what I can tell all valves are 1", all laterals are 1" and all sprinklers connect to 1/2" funny pipe from the laterals.


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## Ecks from Tex (Apr 26, 2018)

Welcome! I have questions.....



> My home provides 11gpm @ 50psi.


How do you know this and at what point in your system was it measured?



> every single rotor zone seems to only operate @ 20psi.


How are you measuring this? Are you measuring each head or what exactly are you doing to make this determination?


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## g-man (Jun 15, 2017)

Welcome to TLF.

How are you measuring the psi at the heads? When swapping to the mp, do you plan to swap the bodies to the regulated ones?

Do the valves have flow controls?


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## mnikon (Jun 7, 2018)

The GPM was done based on pipe size from irrigation tutorials. I also confirmed with a bucket test. The system pressure was taken from the spigot on the irrigation mainline. Each head was tested by placing the gauge inline @ each head in the zone.


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## mnikon (Jun 7, 2018)

g-man said:


> Welcome to TLF.
> 
> How are you measuring the psi at the heads? When swapping to the mp, do you plan to swap the bodies to the regulated ones?
> 
> Do the valves have flow controls?


As of right now the areas with MPs are just using standard Hunter Pro Spray bodies.


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## Ecks from Tex (Apr 26, 2018)

mnikon said:


> The GPM was done based on pipe size from irrigation tutorials. I also confirmed with a bucket test. The system pressure was taken from the spigot on the irrigation mainline. Each head was tested by placing the gauge inline @ each head in the zone.


If I'm in your shoes, my first concern would be that the GPM from my house is not accurate. Irrigation tutorials also cautions against the bucket test. Normally I don't think it would matter if you weren't having an issue, but I think in your situation you've got to play detective, so to speak, and go back to the source. That probably requires you calling your water provider to get supply information (I have done this as well) and then figuring out how to get the most accurate reading at your house.

My worry is that you don't have the pressure you need. Pressure regulated bodies and flow control valves may be in your future, but before you go fixing problems you aren't sure you have, I'd get the most accurate numbers I can.


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## g-man (Jun 15, 2017)

I would do the meter test. Open the meter and record the number. Trigger irrigation and run it for 10mim (without anything else in the house running). Record the second number and calculate your gpm that way.


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## mnikon (Jun 7, 2018)

Ecks from Tex said:


> mnikon said:
> 
> 
> > The GPM was done based on pipe size from irrigation tutorials. I also confirmed with a bucket test. The system pressure was taken from the spigot on the irrigation mainline. Each head was tested by placing the gauge inline @ each head in the zone.
> ...


I was afraid of this. I moved into this home with the irrigation already installed. We have always had pressure issues in the house if the irrigation is running. Mostly noticed when 
I shower in the mornings before work. The more and more research I do the more and more im finding whoever did my irrigation didnt know what they were doing totally. Including every rotor being nozzled exactly the same. This was the main reason why I started digging into this was the uneven watering and dry spots I was getting from my system. The old nozzles were WELL over 11GPM per zone. I have renozzled everything to get approptiate coverage but the pressure issues remain. I will be calling my Water company asap to fogure out what numbers they claim to be offering. I will post back with my findings. Thanks!


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## mnikon (Jun 7, 2018)

g-man said:


> I would do the meter test. Open the meter and record the number. Trigger irrigation and run it for 10mim (without anything else in the house running). Record the second number and calculate your gpm that way.


This is a great suggestion! Funny how one can overlook things. For clarification when you say "Open the meter" are you refering to a spigot? Or something else?


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## mnikon (Jun 7, 2018)

A little more info. on my system......I have 8 zones total. Zone 1 is 6 MP rotator SRs, zone 2 is 4 MP rotator 3000s (1 does 360), zone 3 is 5 MP rotator 3000s, zone 4 is 5 PGP Ultras, zone 5 is 5 PGP ultras (2 heads do 360s), zone 6 is 6 PGP ultras, zone 7 is 6 MP rotator side strips, zone 8 is 6 MP rotator side strips. Zones 1,7,8 do 40psi exactly so tbose are good. Im assuming from the lower GPM. Which seems ultra low at around 2-3GPM only. Keep in mind this entire system was existing and I'm trying to do the best with what I was given.


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## Ware (Jan 28, 2017)

mnikon said:


> This is a great suggestion! Funny how one can overlook things. For clarification when you say "Open the meter" are you refering to a spigot? Or something else?


No I think he's talking about opening the water meter box and getting readings from the dial on the meter. Around here you would need a "key" for the meter box. Also note that some dials read in cubic feet, so you would convert to gallons (1 cubic foot = 7.48 gallons).


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## g-man (Jun 15, 2017)

Zone 6 and 8 have 6 pgp and they are all working? Have you calculated the theoretical GPM for those zones?

Open the meter means going to the yard and finding the metal top that the water company has the water meter at. The meter has the CCF of water measurements.


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## Ware (Jan 28, 2017)

Note 1 CCF is one hundred cubic feet, or 748 gallons. Moral of the story is just pay attention to the units on the meter face. :thumbsup:


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## Ecks from Tex (Apr 26, 2018)

mnikon said:


> Ecks from Tex said:
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> > mnikon said:
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No worries dude even if that's the case it's a problem that can be lessened and you can DIY with a little patience. I don't have a pressure problem but I definitely have/had a coverage problem so I understand how frustrating it can get trying to solve. Gman gave you a good measuring method so just keep troubleshooting.


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## mnikon (Jun 7, 2018)

g-man said:


> Zone 6 and 8 have 6 pgp and they are all working? Have you calculated the theoretical GPM for those zones?
> 
> Open the meter means going to the yard and finding the metal top that the water company has the water meter at. The meter has the CCF of water measurements.


Zone 6 is the only zone with 6 PGPs. Yes they work but only @ 20psi. Zone 8 is 6 MP rotator side strips. Zones 1,7,8 all run fine @ 40psi. Im assuming from the lower gpm consumed by the side strips and SRs. It's only zones where PGPs were initially installed I'm getting 20psi. Including the front zones 2 and 3 where I have swapped PGPs out for MP rotator 3000s. Thank you for the clarification on opening the meter. I will see what I can do with this as I'm in MN and our meters are in the basement to prevent freeze. Mine is burried in a closet unfortunately. May be messy to open the meter up. The theoretical GPM for zones 7 and 8 is only 2.6GPM😔. Theoretical for zone 1 is only 2.3GPM. That seems silly low.


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## g-man (Jun 15, 2017)

Wait the water company goes to your basement every month to bill you? I don't think the meter could be in the basement.

There is a relationship between gpm and pressure drop. As you flow more water it will drop more pressure (more friction with the pipes). Switch to MP will be a positive thing to do since they are lower flow.


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## mnikon (Jun 7, 2018)

g-man said:


> Wait the water company goes to your basement every month to bill you? I don't think the meter could be in the basement.
> 
> There is a relationship between gpm and pressure drop. As you flow more water it will drop more pressure (more friction with the pipes). Switch to MP will be a positive thing to do since they are lower flow.


Yes indeed the basement due to deep winter freezes in MN. They have a wireless transmitter connected to it so they can drive by and read your meter monthly. Cool huh?

Edit. My main issue with the rotators out back is zone 5 utilizes 2 360s and 1 270. Even with the rotators im still over my supposed 11gpm which i think weve determined is completely false lmao. Also the heads are spaced further than the front lawn so even the MP3000s @ 20psi wont give me full head to head coverage.

Edit 2 - Zone 5 theoretical GPM with MP rotators would be 10.08GPM @ 25psi. Technically shy of 11gpm but again that isnt accurate.


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## mnikon (Jun 7, 2018)

Almost wondering if theres an issue with my supply line in the yard feeding the house. 2.6GPM cant be legit can it?


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## Ecks from Tex (Apr 26, 2018)

mnikon said:


> Almost wondering if theres an issue with my supply line in the yard feeding the house. 2.6GPM cant be legit can it?


I'd you know how much the water co supplies you, and what your pressure is at the house, you can probably figure that out.

And you could go dig a small hole at the main and see how big the line is. I'm wondering if the installers put in a small line


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## mnikon (Jun 7, 2018)

Ecks from Tex said:


> mnikon said:
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> > Almost wondering if theres an issue with my supply line in the yard feeding the house. 2.6GPM cant be legit can it?
> ...


I would dig unfortunately water mains are 6ft+ deep here due to deep freeze in winter. Meter comes into the basement under slab.


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## Ecks from Tex (Apr 26, 2018)

mnikon said:


> Ecks from Tex said:
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What size line feeds the meter?


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## mnikon (Jun 7, 2018)

Ecks from Tex said:


> mnikon said:
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3/4" main in, 5/8" meter, 3/4" main out. However, the irrigation is at the tail end of the house main. So everything in the house comes off the main before it heads outside to the irrigation. Changes to 1" out of home to the irrigation after shutoff valve in basement. Not sure if it being @ the end of the main has any affect?


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## g-man (Jun 15, 2017)

3/4 main is pex or copper?


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## mnikon (Jun 7, 2018)

All copper sorry


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## g-man (Jun 15, 2017)

That should be plenty of gpm. Could you have a pressure reducing valve?


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## mnikon (Jun 7, 2018)

g-man said:


> That should be plenty of gpm. Could you have a pressure reducing valve?


There is a 50psi pressure regulator after the meter. I've wondered if that could be the culprit but wasn't 100% sure as I get a static PSI @ 50. It's not until the irrigation is running that the psi drops to 20psi on most zones and the mainline itself.

We've already determined a 10psi drop @ just 2.6GPM.


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## g-man (Jun 15, 2017)

I would check on it. As the flow increases thru the regulator, there will be a pressure drop. I googled this one (Apollo brand) so you could see a 12psi drop with a 10gpm flow. You will need to check yours.

http://sprinklertalk.com/manuals/conbraco/IOM_36c.pdf

I would increase it to 55psi static. Other things to check, clog filters.


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## mnikon (Jun 7, 2018)

g-man said:


> I would check on it. As the flow increases thru the regulator, the will be a pressure drop. I googled this one (Apollo brand) so you could see a 12psi drop with a 10gpm flow. You will need to check yours.
> 
> http://sprinklertalk.com/manuals/conbraco/IOM_36c.pdf
> 
> I would increase it to 55psi static. Other things to check, clog filters.


 :thumbup: Good info. Looks like maybe I'll look into the pressure regulator, could be it after all. God only knows how old it is. House was built in 1959. It certainly seems to be a supply issue of some sort. I just had to be sure I wasn't going crazy cause ive reverse engineered this thing in my head about a million times now.


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## Ecks from Tex (Apr 26, 2018)

mnikon said:


> g-man said:
> 
> 
> > I would check on it. As the flow increases thru the regulator, the will be a pressure drop. I googled this one (Apollo brand) so you could see a 12psi drop with a 10gpm flow. You will need to check yours.
> ...


Yeah that's a huge red flag to me. And I bet you've got an old in line filter close by too or at the valves. I would at a minimum check both, clear filters and increase regulated pressure. But I would also consider replacing them with something newer from sprinkler warehouse.com if feasible.


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## mnikon (Jun 7, 2018)

Ecks from Tex said:


> mnikon said:
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I dont appear to have any in line filters before the valves. Unless they're buried before the valve boxes. Irrigation comes out of house to backflow preventer then there's a hose spigot then straight into the ground to the valves.


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## g-man (Jun 15, 2017)

The manual from the Apollo prv shows a mesh/filters. I don't know what prv model you have but it might have one too. The Apollo manual describes the need for maintenance and how to do it. Try to find the manual for your model/brand.


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## Ecks from Tex (Apr 26, 2018)

mnikon said:


> Ecks from Tex said:
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If you troubleshoot and still aren't sure, I would suggest posting some pictures of your meter intake/output, your piping setup in the basement, your valves, the pressure regulator, etc. Might help diagnose. The filters won't be buried and unaccessable, so no need to go down that path.


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## mnikon (Jun 7, 2018)

I have a call into the city. They're having someone come out to determine if the problem is on their end. I will post more info when I hear back from them.


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## mnikon (Jun 7, 2018)

So I have to apologize slightly. Apparently I do NOT have a pressure reducing valve after my 
water meter. I am not sure why I thought I saw one at some point. Here's a few pictures of the meter setup in the front of the basement as well as a few other pics of the system. The main runs through a finished ceiling with the only branches before it exits the rear of the house for irrigation being the bathroom cold water and water softener (I guess they didn't care about soft cold water in the main level bathroom). I know those are the only branches because I finished the ceiling myself. The rest of the house comes off of the softener output. I also wanted to mention that we often hear our backflow preventer clicking/ticking even without using any water source. Not sure if this is also a sign of low house pressure?


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## mnikon (Jun 7, 2018)

Ok all, i really appreciate all the help you guys have provided so far! The city had a chance to stop out and check things out on their end. He was unable to provide any sort of GPM statistic but did say the mains are regulated @ 50psi. He said it's all based off gravity from the water tower in my area. His only suggestion was to upgrade from my current 5/8" meter to a 3/4" meter to eliminate any restrictions due to pipe size/meter size. He said this may help with flow rate a little. I will be getting the meter upgraded hopefully within the next week but figured I would reach out to get your thoughts and opinions on the situation. Thanks again for all the help guys!


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## Ecks from Tex (Apr 26, 2018)

mnikon said:


> Ok all, i really appreciate all the help you guys have provided so far! The city had a chance to stop out and check things out on their end. He was unable to provide any sort of GPM statistic but did say the mains are regulated @ 50psi. He said it's all based off gravity from the water tower in my area. His only suggestion was to upgrade from my current 5/8" meter to a 3/4" meter to eliminate any restrictions due to pipe size/meter size. He said this may help with flow rate a little. I will be getting the meter upgraded hopefully within the next week but figured I would reach out to get your thoughts and opinions on the situation. Thanks again for all the help guys!


Yes I agree on the meter upgrade; with your low water pressure you don't want to leave any pressure on the table. I'll be honest I hadn't had a chance to look closely at your most recent pictures, but I'll mark this thread so I can go through and see if there is anything else that stands out. It's eventually going to all come together for you!


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## g-man (Jun 15, 2017)

Meter upgrade should help. Lowering the gpm of a zone will also reduce your pressure losses.

One of your valves (3rd second image) has a flow control. Make sure it is open enough for that zone. Also check all the gate valves to be fully open (I like ball valves better).


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## mnikon (Jun 7, 2018)

Ok, im installing the 3/4" meter right now. Checked the flow control on the 1 valve and it's wide open so that shouldn't be an issue. Im struggling to lower the GPM per zone especially zone 5 as there are 2 - 360* heads, 1 - 270* head, 1 - 180* head, and 1 -90* head. The 2 360*s on one zone make it tough to keep the GPMs low. As of right now theyre doing 3GPM with the 270 doing 2GPM and the 180 and 90 both doing 1.5GPM for a total of 11GPM. I realize the 90 and 180 should technically be a lower GPM but the standard blue nozzles only do 1.5GPM on the smallest nozzle. Its looking like i may have to switch to the red nozzles and increase my run times unfortunately. Im skeptical on switching the back lawn to MP rotators as I don't believe they'll offer full head to head coverage with only 20psi. I could draw a rough sketch of the backyard with head spacing and post a picture to get your guys thoughts if you think it could help.


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## mnikon (Jun 7, 2018)

The new 3/4" meter is in and I'm happy to say it was worth the effort! I have easily gained an additional 10psi @ each head putting me in the 30psi range in my larger zones now. Also my house water works far better with the irrigation running. I'm easily getting an additional 6-8ft from each head which helps me feel far better about making the switch to MP Rotators in the back lawn. Can't thank you guys enough for all the help and direction through this!! You all rock!!


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## g-man (Jun 15, 2017)

One big benefit of the mp is the lower gpm per zone. This means lower pressure losses (by a square factor if I remember the formula correctly). You do have to run the zone longer to get more total precipitation.


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## Ecks from Tex (Apr 26, 2018)

mnikon said:


> The new 3/4" meter is in and I'm happy to say it was worth the effort! I have easily gained an additional 10psi @ each head putting me in the 30psi range in my larger zones now. Also my house water works far better with the irrigation running. I'm easily getting an additional 6-8ft from each head which helps me feel far better about making the switch to MP Rotators in the back lawn. Can't thank you guys enough for all the help and direction through this!! You all rock!!


Awesome! Great news

I would suggest pressure regulated heads for the MP rotators. Will keep them working as intended


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## mnikon (Jun 7, 2018)

Ecks from Tex said:


> mnikon said:
> 
> 
> > The new 3/4" meter is in and I'm happy to say it was worth the effort! I have easily gained an additional 10psi @ each head putting me in the 30psi range in my larger zones now. Also my house water works far better with the irrigation running. I'm easily getting an additional 6-8ft from each head which helps me feel far better about making the switch to MP Rotators in the back lawn. Can't thank you guys enough for all the help and direction through this!! You all rock!!
> ...


Is there a benefit to the regulated heads even if you're not getting 40psi or greater on a zone? I did upgrade my largest zone out back already and am still questioning the MP rotators back there. Even with the flow increase I'm still only achieving ~20psi @ the heads on this zone. The zone uses 10.08GPM @ 20psi being there are 2 - 360s, 1 - 270, 1 - 180, and 1 - 90. Maybe a leak in a lateral somewhere but i don't get any soaking puddle areas after running the system, or just the GPM are too high still. I am contemplating moving a head off this zone to another that's only using ~5GPM with rotators to help balance things better.


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## Ecks from Tex (Apr 26, 2018)

mnikon said:


> Ecks from Tex said:
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Having low psi, you could regulate pressure under 40 psi to each head and that might give you some uniformity, so at the very least you could assess whether you're getting proper coverage.

But I am in agreement, you've done all you can at the meter and now you need to start looking at the zones.

You were able to confirm there is not a pressure regulator after the meter, correct?

Have you read this page on irrigationtutorials.com? https://www.irrigationtutorials.com/balancing-pressure-irrigation/ It might be helpful to give you some ideas on how you need to assess your down-the-line psi problem.

30 psi at the heads is not optimal but definitely workable. Much better than a few days ago. It sounds like you have a good idea how to rearrange your zones, but i suppose we'd need to see a simple sketch to be able to weigh in on the logistics. The numbers you mentioned in reference to moving a head to a better zone works.


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## Rain Bird Corp (Jun 6, 2018)

mnikon said:


> Is there a benefit to the regulated heads even if you're not getting 40psi or greater on a zone?


If a Rain Bird 1800 PRS series spray head is installed on a line with pressure equal to or less than its pressure set rating, there will be no pressure benefit. There will be a small amount of additional pressure drop through the head resulting lower pressure provided to the nozzle compared to a spray head with no PRS device.


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