# What's the Minimum amount of water pressure?



## jpos34 (Aug 31, 2019)

I'm looking at possibly doing a install of irrigation myself but trying to figure out a lot of questions. I bought a pressure tester from Lowe's and on my outdoor spigot I'm getting exactly 40PSI, which I feel like I need more than that. I'm my basement I have a fire sprinkler system that is installed off the main water line before the pressure regulator and it's showing a reading of 110 PSI roughly. I tried adjusting my pressure regulator to increase the 40 PSI but it didn't increase any. Would I be installing my irrigation system of the main line before the pressure regulator or does it go after the regulator? If after can I change regulator out to a larger one in order to get more pressure. It took my outdoor spigot exactly 1 min to fill a 5 gal bucket for reference.


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## ENVY23 (Sep 14, 2021)

It goes off the mainline, usually right after the meter so it's easier to find the waterline to tie into, but definitely before your pressure reducer. I installed my own at my last house, so I'm happy to answer any questions.


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## g-man (Jun 15, 2017)

I would try to figure out why your pressure is so low. Maybe you have an issue with the regulator. You want the pressure to be around 65psi. High pressure sounds great, but they do cause more damage and water hammer. Irrigation tutorials recommends to go after the regulator.


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## jpos34 (Aug 31, 2019)

g-man said:


> I would try to figure out why your pressure is so low. Maybe you have an issue with the regulator. You want the pressure to be around 65psi. High pressure sounds great, but they do cause more damage and water hammer. Irrigation tutorials recommends to go after the regulator.


You think I need to get a plumber to look at the regulator? I've adjusted the bolt on top of the regulator and it didn't change the pressure at all. I really would like to do the install
Myself to save money but also thought about getting someone out for a quote and they may have a suggestion as what to do as well. What do you think get a plumber or Do you know any DIY ways to check for faulty regulator


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## g-man (Jun 15, 2017)

Find the manual for the regulator and use it to make sure you are adjusting correctly. It might need a flush/cleaning or something like that.


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## ENVY23 (Sep 14, 2021)

g-man said:


> I would try to figure out why your pressure is so low. Maybe you have an issue with the regulator. You want the pressure to be around 65psi. High pressure sounds great, but they do cause more damage and water hammer. Irrigation tutorials recommends to go after the regulator.


Are you sure? https://www.irrigationtutorials.com/connect-sprinkler-system-to-water-supply/

_"after any water meters and before the house emergency shut-off valve"_

Every house I've owned, the shut-off valve is the first thing in line once the pipe enters my house. Right behind it is the pressure regulator. Now, irrigation tutorials _does_ say that if your pressure is over 100psi at the connection point, you will need a pressure regulator there to bring your irrigation system below 100psi. In this case, you would tap into your mainline with a T, install a shut-off valve, then the pressure regulator, followed by your backflow preventer.

Not trying to nitpick, I know I'm new here, but I was a member of the "other site" and just recently found this one. I have a lot of respect for you and everyone here, since starting this obsession I have a learned a ton from you all.


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## g-man (Jun 15, 2017)

To me it is implied in this section, if 55PSI is good, why have double?:



> For a pressure regulator to work accurately the pressure setting on it must be at least 15 PSI lower than the inlet pressure. So if your static pressure is 70 PSI, the highest pressure you should set on the pressure regulator would be 55 PSI. 55 PSI is a good pressure for both the needs of a house and a sprinkler system.


In the OP case, I think 110PSI is just too much. I know Hunter valves can handle 150psi, but I think you can get a lot of mist at those pressures in the nozzles.

There is a whole section on just this topic. https://www.irrigationtutorials.com/gpm-psi-municipal-water-source/


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## ENVY23 (Sep 14, 2021)

I totally agree 110psi is too much. I just don't like the idea of tapping into the lines inside my house. If you tap into the line inside your house, then you have to drill a hole in your house to run that line back outside to the valve box(es), etc. Of course I guess it depends how your house/water lines are setup, but it just seems like more headache to me. I prefer to keep things as separate as possible, so that any issues are isolated and don't effect one another. Pressure regulators are relatively cheap so I would install a 2nd one like I mentioned above, between the irrigation shutoff and the backflow preventer, to get him to a more reasonable PSI.


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## jimmythegreek (Aug 7, 2020)

Depends where in the USA you're from. Cold climates it's all inside. Warm can be outside. Drilling thru house is no big deal. You always want a shutoff for the irrigation right off main line. If above 70psi use a reducer. You can run higher it just eats valves quicker. Fine to tap ahead of anything household with a T just valve it off for emergency amd service. You dont want to use street shutoff for irrigation


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## jpos34 (Aug 31, 2019)

My home is 3 years old next month, and I've only ever been able to run 1 water hose at a time due to low pressure. Do you think I could have had a faulty regulator from the get go? Any way to test the regulator short of just replacing it all together?, I've searched the Web but coming up short in my searches. I wouldn't necessarily mind tapping into the main line outside but I would also like to test that pressure to be sure that I would get enough pressure directly from the city but Im not sure how I would do that. As I stated and showed in the picture in my original post my sprinkler system is before the regulator and shows a pressure of 110 but I don't know all the ins and out of a sprinkler system so I didn't know if they put some kind of pressure booster on that or not.


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## Frankzzz (Aug 23, 2021)

I just looked at the instructions that came with my pressure regulator that I had replaced by a plumber just a few years ago. For mine, you have to tighten the bolt (turn it clockwise) to increase pressure. (I thought that was the case, is why I checked the instructions to be sure.) I know, it's counterintuitive. 
Just looking at a few youtube vids on how to adjust it, that seems standard for water pressure regulators. It also seems to be standard that they usually come factory set at 50psi.

So, you might want to try that with yours, just in case. Otherwise, you need a new regulator. No way to test it, other than adjusting it and measuring like you've already done.

If you are able to increase it, you don't want to increase above about 55 psi. Things inside your house like toilets, refrigerator ice maker / water dispenser, washing machine, and dishwasher, can only handle around 60-70 psi.

Read the tutorial that g-man linked above.


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## PerennialRyeglass (Sep 9, 2021)

I strongly recommend getting a second PRV for your irrigation. What size is your regulator? Should be 3/4". I've seen some ridiculous set ups where immediately after the meter, the pipe is reduced to 1/2". The volume of water able to travel through 1/2 vs 3/4 is quite substantial. Unless you get it absolutely screaming through there, flow will always reduce when multiple fixtures are used.

I'd tee off before your PRV, add your valve, irrigation PRV, and BFP. If you wanted to, provided you have exposed pipes in your basement ceiling, crawl space, whatever you have, you can cut the current water supply to your spigots off, cap it, then run your newly teed irrigation line to them. Then its just your hose spigots that you already have that will have higher pressure and the rest of the house can remain unchanged. No new holes in the wall.


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## jpos34 (Aug 31, 2019)

@PerennialRyeglass I have a 5/8 meter, with 3/4 coming out and into the house. I sent a design request to rain bird but they said my GPM isn't enough. It took exactly 60 seconds to fill a 5 gallon bucket so 5 gpm, said I need a minimum of 8. To me it seems that GPM is my main concern and not the pressure as I would probably just tee into the main line outside the house. I have a basement so everything is exposed to be able to adjust/modify as needed. Is there anyway to increase the GPM that I'm getting?


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## PerennialRyeglass (Sep 9, 2021)

jpos34 said:


> @PerennialRyeglass I have a 5/8 meter, with 3/4 coming out and into the house. I sent a design request to rain bird but they said my GPM isn't enough. It took exactly 60 seconds to fill a 5 gallon bucket so 5 gpm, said I need a minimum of 8. To me it seems that GPM is my main concern and not the pressure as I would probably just tee into the main line outside the house. I have a basement so everything is exposed to be able to adjust/modify as needed. Is there anyway to increase the GPM that I'm getting?


Provided you haven't maxed out the outlet pressure of the PRV, you could try to boost it up a bit. Technically, you could just keep increasing pressure until you get your 8gpm. The problem is you'll reduce the life of your PRV, potentially blow up fittings, have incredibly loud pipes, among other issues. This is why its impractical. By having a dedicated line for irrigation with an appropriately sized PRV, you can keep your house quiet and safe, and just have a larger high volume line to your irrigation.

Do you have a laundry tub or something closer to the PRV? Every fitting in a system causes a restriction to flow, and so volume decreases and back pressure increases. Try the bucket test with whatever faucet is closest to the PRV.. see if there's much of a difference before any adjustments. Its hard to make an accurate recommendation without being able to see the system.

I may try to math it out tonight if I get a chance. It's been a while since I've dipped into fluid dynamics.. I'm a bit rusty.

Do you see a model number on the PRV?


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## jpos34 (Aug 31, 2019)

PerennialRyeglass said:


> jpos34 said:
> 
> 
> > @PerennialRyeglass I have a 5/8 meter, with 3/4 coming out and into the house. I sent a design request to rain bird but they said my GPM isn't enough. It took exactly 60 seconds to fill a 5 gallon bucket so 5 gpm, said I need a minimum of 8. To me it seems that GPM is my main concern and not the pressure as I would probably just tee into the main line outside the house. I have a basement so everything is exposed to be able to adjust/modify as needed. Is there anyway to increase the GPM that I'm getting?
> ...


 Apollo36 CLF-104-01


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## PerennialRyeglass (Sep 9, 2021)

[/quote]
Apollo36 CLF-104-01
[/quote]

So, looking at the specs of that PRV, you should be able to adjust it get up to 75psi. I wouldn't go above 60. Not because of the stress on the PRV but more so because that's about the limit that code generally dictates for the sake of safety on your pipes. I know you said you've tried adjusting it and had no luck. You can take the nut off the bottom of the unit, with the water shut off of course, and see if the strainer is clogged or restricted.

If its clean, and you are for sure not getting any difference with adjusting it, then it's likely pipe size restriction. 60psi should be able to deliver 8gpm. Technically 40psi SHOULD do it, based off some charts I have.


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## jpos34 (Aug 31, 2019)

Apollo36 CLF-104-01
[/quote]

So, looking at the specs of that PRV, you should be able to adjust it get up to 75psi. I wouldn't go above 60. Not because of the stress on the PRV but more so because that's about the limit that code generally dictates for the sake of safety on your pipes. I know you said you've tried adjusting it and had no luck. You can take the nut off the bottom of the unit, with the water shut off of course, and see if the strainer is clogged or restricted.

If its clean, and you are for sure not getting any difference with adjusting it, then it's likely pipe size restriction. 60psi should be able to deliver 8gpm. Technically 40psi SHOULD do it, based off some charts I have.
[/quote]

When you say pipe size restriction I have a run of about 100 feet from where meter is till main line runs into my basement. Pipe is 3/4 pex. Could I realistically run a larger line from meter to my house to get more water volume? Or tap sprinkler system line right near meter. I figured if I had trencher already I may as well run a larger line to my house anyways to help with volume in the rest of the house?


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## PerennialRyeglass (Sep 9, 2021)

jpos34 said:


> Apollo36 CLF-104-01


So, looking at the specs of that PRV, you should be able to adjust it get up to 75psi. I wouldn't go above 60. Not because of the stress on the PRV but more so because that's about the limit that code generally dictates for the sake of safety on your pipes. I know you said you've tried adjusting it and had no luck. You can take the nut off the bottom of the unit, with the water shut off of course, and see if the strainer is clogged or restricted.

If its clean, and you are for sure not getting any difference with adjusting it, then it's likely pipe size restriction. 60psi should be able to deliver 8gpm. Technically 40psi SHOULD do it, based off some charts I have.
[/quote]

When you say pipe size restriction I have a run of about 100 feet from where meter is till main line runs into my basement. Pipe is 3/4 pex. Could I realistically run a larger line from meter to my house to get more water volume? Or tap sprinkler system line right near meter. I figured if I had trencher already I may as well run a larger line to my house anyways to help with volume in the rest of the house?
[/quote]

3/4" should be fine. I have yet to see a house that has larger than that supplying it. Did you check the strainer in the prv? I assume your meter isn't in your house then eh? 
Whether you tee off of your main line to the house inside or out, it'll be the same result. You'll still need a separate PRV so you don't put the 110psi to your sprinkler heads.

You SHOULD be able to get your 8gpm though that existing prv though.. so something's up if you can't. Im not an irrigation expert, so for that, maybe someone else has a better idea. However, I do make a living installing various piping systems so that part I do understand.

Any pictures of the PRV and the piping around it? Where the sprinkler take off is? Just trying to get a better idea of what's going on there.


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## jpos34 (Aug 31, 2019)

@PerennialRyeglass Here are some pictures. Let me know if you have any questions.


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## g-man (Jun 15, 2017)

1/2in pex sucks for water flow. Did you try to adjust the prv?

By the way, whoever installed that valve on top of the electrical panel was not thinking.


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## PerennialRyeglass (Sep 9, 2021)

jpos34 said:


> @PerennialRyeglass Here are some pictures. Let me know if you have any questions.


I want to slap the plumber that made that mess. That's a short run. I'd swap it for 3/4 just because it's so easy.

On your sprinkler, to the left of the gauge reading 110, what fitting is on the dead end there? I can't zoom in to see.

Reason I ask is, is that a dry pipe sprinkler? If it is, that 110 psi could actually be air pressure. Unlikely for residential but I don't know code for your area. That fitting almost looks like it's a male end for an air compressor to hook up to.

At least it's expansion pipe/fittings so you don't get the normal choke points at crimped PEX fittings. With crimped the fitting has to fit inside the pipe, so actual ID is closer to 3/8 for 1/2. With expansion you maintain ID as it should be.


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## jpos34 (Aug 31, 2019)

PerennialRyeglass said:


> jpos34 said:
> 
> 
> > @PerennialRyeglass Here are some pictures. Let me know if you have any questions.
> ...


 Does this picture help? It looks like a male fitting to me. when you say dry sprinkler what does that actually mean? Also are you saying that you would run a 3/4 to that spigot?


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## PerennialRyeglass (Sep 9, 2021)

jpos34 said:


> PerennialRyeglass said:
> 
> 
> > jpos34 said:
> ...


So there's dry pipe and wet pipe sprinklers. Dry pipe, from the valve to the sprinkler heads is filled with compressed air. This keeps the pipes dry. The air pressure is higher than water pressure to keep the valve closed. When the air is released from a head going off, the water pushes the valve (basically just a check valve) open and you get water.

Wet pipe, the entire system is full of water right up to the sprinkler heads.

Looks like a hose thread though. Let me think on that for a minute


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## g-man (Jun 15, 2017)

g-man said:


> Did you try to adjust the prv?


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## jpos34 (Aug 31, 2019)

g-man said:


> g-man said:
> 
> 
> > Did you try to adjust the prv?


I did but to no avail. nothing changed.


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## PerennialRyeglass (Sep 9, 2021)

jpos34 said:


> g-man said:
> 
> 
> > g-man said:
> ...


Edit:
So now that I have a minute to look at it on a larger screen, it'll be a wet pipe system. That hose fitting is for draining the system. So, chances are, the PRV has failed, or the strainer is partially blocked. You can hook a garden hose to that fitting, and SLOWLY crack the valve open. If the pressure stays steady and you can tell it's just water, then your prv has failed. You may or may not have that alarm bell go off above your head lol but it should shut off once you shut the valve and the flow stops.


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## jpos34 (Aug 31, 2019)

@PerennialRyeglass If you look at the initial post of the pressure gauge showing 110 it says Air/Water. as for any other markings I would have to look when I get home.


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## PerennialRyeglass (Sep 9, 2021)

jpos34 said:


> @PerennialRyeglass If you look at the initial post of the pressure gauge showing 110 it says Air/Water. as for any other markings I would have to look when I get home.


Yep, that just means the gauge is suited to be used on both air, or water systems. That's all.


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## jpos34 (Aug 31, 2019)

PerennialRyeglass said:


> jpos34 said:
> 
> 
> > @PerennialRyeglass If you look at the initial post of the pressure gauge showing 110 it says Air/Water. as for any other markings I would have to look when I get home.
> ...


 When I get home tonight I will look for any other kind of indicators, if it comes down to it ill call the guy that installed the system,. I got a card from him when the house was built.


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## MasterMech (Sep 24, 2017)

jpos34 said:


> @PerennialRyeglass I have a 5/8 meter, with 3/4 coming out and into the house. I sent a design request to rain bird but they said my GPM isn't enough. It took exactly 60 seconds to fill a 5 gallon bucket so 5 gpm, said I need a minimum of 8. To me it seems that GPM is my main concern and not the pressure as I would probably just tee into the main line outside the house. I have a basement so everything is exposed to be able to adjust/modify as needed. Is there anyway to increase the GPM that I'm getting?


If you're measuring GPM at a house spigot - you are losing flow due to your home plumbing and the PRV which is dropping the pressure to 40 psi. To be 100% accurate, you need to measure the flow AFTER installing the irrigation tap near the meter. I also have a 5/8" x 3/4 meter, and 3/4" incoming Pex. I have less than 100 psi of incoming pressure for sure and I have no trouble running 5-6 heads pulling 2-3 GPM each with my irrigation tie in directly after the meter.

ETA: It's Flow @ psi that matter too. You need to measure the flow with the pressure gauge at operating psi for your system. So if you plan on designing around heads that need 40 psi, you need need to throttle the flow until your gauge reads your design pressure + any built in pressure drop due to piping or valves. Let's say you calculate losing 5 psi to valves and piping, you need to measure the flow with your pressure gauge reading 45 psi.


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