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superD

New Member

1

Saturday, April 20th 2013, 8:05pm

Low Water Pressure

Hi, This is my first post, so I hope I put this in the right place.

My yard is pretty big, almost 1/2 acre
I want to install a sprinkler system so I have been gathering some information

I am on city water and have a 1 inch meter. I dug down to the main line and it is 1 inch too. PVC.

I measured the water pressure at my hose spigot and I was surprised to see that the gauge said I have 40 PSI. Since Im on city water, that seems real low to me. its about 70 feet from the meter to the hose spigot.
I thought maybe the gauge is bad so I went to the hardware store and got another and It also says I only have 40 PSI.
I still didn't believe it so went to the neighbors house and they also have 40 psi at the hose spigot.

I measured several times all through the day today and it never changed any measurable amount.

At 40 PSI, I really cant see installing so many zones to make it work. Or I guess installing some real big pipes to decrease the losses.

So, I guess my question is this. Is there some sort of pump or something that could boost the water pressure?

Funny thing about this whole thing is, the wife dug out our home inspeciton from 4 yrs ago and the inspector noted the water pressure at 60-70. can it go down that much? I dont have any leaks anywhere. no new construction within a couple of miles of me.

Im really at a loss, no pun intended, on what the best option is, or to just scrap the idea.

thanks

Wet_Boots

Supreme Member

Posts: 4,087

Location: Metro NYC

2

Sunday, April 21st 2013, 11:52am

If you live in an area of new construction, pressure will drop as more homes are connected to the water supply. In any event, you should be prepared to proceed based on your measurements.

3

Monday, April 22nd 2013, 12:12am

make sure you have checked at different times of the day....i.e morning, lunch, and midnight for consistency. ;)

superD

New Member

4

Saturday, April 27th 2013, 12:51pm

Ive been checking the gauge all week during mornings evenings and nights. The lowest reading I have seen is 38, the highest is about 42.
No new construction anywhere even close to me. I called the water department an found out they have regulated the water pressure in my area of town to about 45 last year with plans to drop it a bit more in January.

Given the pressure I have now, and the amount of yard to water, and a future decrease in pressure, it looks like my design will need a booster pump. Looks like I have a lot of learning to do about those things.

Wet_Boots

Supreme Member

Posts: 4,087

Location: Metro NYC

5

Saturday, April 27th 2013, 1:11pm

If you have a 1-inch meter in a pit near the curb, you can tap into the main just downstream of it and upsize everything from that point on.

Even with the low pressure, you can get by, on a half-acre property. It just won't be as cheap and easy compared to having a 100 psi street pressure. You'll need to do all you can to preserve the water pressure.

Sight unseen, the largest concern is if the property slopes uphill from the water supply, perhaps making it necessary to employ a pressure-robbing RPZ backflow preventer.

Where's your location?

superD

New Member

6

Saturday, April 27th 2013, 3:46pm

Im in East Texas in a town called Longview.

My house is on the highest part of the lot, and the ground slopes away slightly from the house on all 4 sides. Elevation change from the house to the meter is about a foot I would say. 15 inches at the most. Distance is about 60 feet. 15 feet from meter to the road.

just as a fyi, there is not very good soil here. Its mostly red clay and water dont sink in quick, so I think light water application would be best for me. So I was looking at the rainbird and hunter rotary sprays that have a decent radius but low precipitation rate. from what Ive read about them, they work best from 35 - 40 psi. for those, I just couldnt tolerate hardly any loss at all.

I will keep figuring it out though and looking at different sprinklers to and see what I can come up with. This is getting interesting for me and Im liking learning new stuff along with the challenge.

pass1

Active Member

Posts: 34

Location: east coast

7

Saturday, April 27th 2013, 4:15pm

low static

You are going to be hard pressed to have any more than 25-28 psi at the heads.. Buy the time you figure your pressure losses through the service line from the street, the meter, any check valves, backflow device, valves, mainline, lateral lines, fittings, elevation, it's all going to add up. Of course, your losses are going to be based on how much flow ( gpm) you have. Do your math carefully on this one.

superD

New Member

8

Saturday, April 27th 2013, 4:45pm

low static

hi Pass1,

yup. Its interesting. I actually helped a friend of mine for the last month or so install his sprinkler. His works great by the way. First time for both of us. That's what got me on the kick of installing myself one.

As it turns out he has a lot more pressure than I do, I think because he lives real close to the water tower and is in a relatively new neighborhood and has better infrastructure.

I didnt quite fully understand the whole pressure loss deal (probably still fully dont) which is why I was kind of shocked when mine is about 40 and he has about 60. I have learned a lot about this in the last week or so. - I even measured from my house to the nearest water tower, and the elevation difference too! Im just that way, Im the kind of guy that I need to actually understand what is going on.

I think the wife is about put out with me too because of it! :huh:

Wet_Boots

Supreme Member

Posts: 4,087

Location: Metro NYC

9

Sunday, April 28th 2013, 1:01pm

For the money, you might do best with the 'primitive' Rainbird Maxipaw impact heads. They can actually function well with 25 psi at the heads.

As for the heavy soil, you might want to explore the concept of "Cycle and Soak" and see how it applies to watering heavy soils with sprinklers capable of causing runoff problems.

Scott76

Active Member

Posts: 46

Location: Kansas City

10

Thursday, May 2nd 2013, 1:23pm

By using a spigot on the house, you have all of the drop through the meter accounted for. If you tap in the yard, by the meter can, you will actually have a bit more pressure. You drop pressure through every turn in the piping from the meter to the spigot. This will eliminate multiple that are in the house. Your flow rate is a huge factor in your friction loss in the piping you use.

This chart is very helpful in determining how to lay out your system. http://www.irrigation.org/uploadedFiles/PDF_Documents/IA_Friction_Loss_Charts.pdf

Mind you the loss listed is per 100 foot of pipe, but if you plan your runs accordingly, you will see that you won't drop too much if you keep your flows as low as possible. If you have 40 psi at the tap and run 500 feet to a head through 1" schedule 200 pipe you will have 38 PSI at the head if you are flowing 5 GPM out that head. Knock the flow down to 2 GPM and you have 39.65 PSI at the head.

Hunter makes the MP Rotator, which is a low flow head that uses a 4" pop up spray body. You can get those 4" sprays with PRS, which will regulate the pressure out the head to a fixed PSI, so long as you have the pressure at the head. Hunter makes the PRS with different pressure outputs, 30 and 40 psi. Rainbird makes a 4" PRS head with a 30 PSI output. Use those along with some math and a system is more than designable. It's going to have many more zones than your friends, but it's certainly doable if you want to spend the money.

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