Water line sizing

[AA7483]

I recently trenched a water line out to my house, probably about 80 feet or so to the house. This is going to be used for a hand washing sink and a hose bib. I ran 1" poly. The point where this pipe enters the house, I only have a 3/4" cpvc line to tie into. I'll also be tying in my irrigation for that side of the property to that 1" line. I purchased the property next door where I built the shop. Ill be irrigating about a quarter acre. My concern is having enough pressure taking my 1" out of the 3/4". Its going to be damn near impossible to access the 1" line that comes into the house where the meter is. Its at the opposite corner across driveways and sidewalks and through a finished portion of the basement on the inside.

 

[sberry]

The inch will help with pressure loss on the 80 ft run. It's not a problem putting the 3/4 to it. It doesn't hurt other than to allow a little more to flow.
Where there is limited flow or the possibility of more demand than supply larger lines and fittings allow for more and can drop system pressure. This is why the downsize and supply tubes for sink and toilets and why frost free and common hose bibs exist, they want some resistance so it doesn't *** gushers and drop the pressure every where, flush and scald in the shower etc.
In my own case have a bigger system, 1 1/4 pipe to the shop, a couple inch branches and big enough tank that i can open a 3/4 valve and still have system pressure, I fill some tanks etc.

 

[joes99]

Do you have a pressure reducing valve inside your house? I would connect to the entrance line before that. I think that you would need the additional pressure to run irrigation and cover the distance

 

[sberry]

Just like electric it is based on use and load. If the line is too small there is friction loss, increases as demand goes up. If the irrigation sprinkler is too big it causes pressure drop. You do not reduce the pressure at the start, if you wanted to do that could simply use a smaller line or hose. Inch poly is good for this job, most of the loss at hi demand is going to occur on the 3/4 section which will be somewhat of a choke, acts as a reducing valve to some extent.
Open a big valve at one point and won't have any pressurev atv the kitchen sink. This is about applying the correct load.

 

[AA7483]

Im not super concerned with pressure at the shop. Don't think that will be an issue. More concerned with the irrigation. Just to clarify, the irrigation line will be coming from the house, not after the 80 ft run to the shop. My concern really is just that the 3/4 line comes from the front of the house where it comes off of the 1" main. Just concerned with using the 3/4 line to tap my irrigation and shop supply off of. Getting back to that main just really isn't an option.

 

[larry_g]

You'll be fine running a sprinkler off of the 3/4" coming from the house. You could also tap into the 1" line anywhere and be fine. I run 2 #30 rainbirds off of 5/8 hose that is 100' long and they work fine. Go do the math and check the flow rates of your 3/4" at the pressure your system is running at. Then check the flow rates of different sprinklers available to you. You don't say if your using hose and a sprinkler or a buried system and popup heads.

lg
no neat sig line

 

[ripperd]

Irrigation will still work, you just may need to use smaller zones than you could with full 1". Are you having a company do the irrigation? They should flow test the hookup being used to determine the GPM/pressure, and therefor maximum zone size.

 

[Falcon67]

We have a well for irrigation. I can run 6 good size rotator heads off a 1" line covering about a 60x50 area. All the spider lines to the heads are 1/2" standard push hose, but you have to get the volume there first. Depends on what you mean by "irrigation". 3/4" isn't going to do squat on 3/4 acre IMHO. The lot next to our house is where the shop sits and is 65 x 110. To cover that was 4 1" lines and 12 heads. I cut and killed off two of those lines that ran under the shop. You could figure that if allowed to go 360 degrees, the heads could have covered around 120x170 total area more of less. Note that was 4 zones of which 2 could run at one time thanks to well volume. If you intend to water all of 3/4 acre, I see a lot of pipe runs, many heads, several zones and staggered watering. Hope city water is cheap where you live.

 

[larry_g]

http://www.rainbird.com/sites/default/files/media/documents/2018-04/Charts_30Hand30WH.pdf

The OP stated ~ 1/4 acre to be watered.

Ill be irrigating about a quarter acre.

If you check the above link you will see that two of the sprinklers above will cover that and more. I use one of the above and a #35 which can be set for part circle. For the OP he might use one #35 and two sets to get the job done. It depends on the layout of the parcel and the water available. It also depends on that amount of automation required. I still drag hoses to water this place.

lg
no neat sig line

 

[buzzworth]

Water pressure vs water volume.
Hook up a line to you 3/4" line and see how many 5 gallon buckets you can fill in a minute.
This will give you a baseline for calculating your sprinkler.

 

[JCQuick]

I have a 3/4" line comming off a 1" from my well to shop about 60' no problem with pressure at all. Its just for sink and hose bib