Water line question advice needed

[Ohmthis]

I'm getting ready to trench my water and power to my pole barn. My question regarding my water is this. Would running a 3/4" line to my barn be stupid if I'm tying it into a 1/2" at the house? I don't have access to run the line to bigger tubing in the house. Running 1/2" out there seems inadequate. BTW the run is 430' and I will only have a sink and maybe a urinal later. I thought about a separate meter and main line, but that is over 650'. Thanks for any advice given.

 

[Aquamoose]

Interesting, your setup is practically identical. I ran 1" to my well and it supplies an urinal, sink, and two hydrants. It certainly doesn't hurt at all to go bigger in case your 1/2" increases down the road.

DO bury it below the frost line and use the black plastic piping made for that. I ran it in 3" pipe along with electric heat tape inside it to protect against freezing from the ground down 4 ft., past the frost line.

I also buried my electric in the same trench. You may want to throw in cables for Internet, phone, cat 5 for future use. One thing I wished I'd done was plumb for air to my garage while keeping the compressor in the shop.

 

[roscoe2000]

Make sure when you backfill to a strip of caution tape a few inches above your electrical lines the full length of your run for future excavations in that area. That way anyone will know that utilities are buried below.

 

[fwerring]

I'd at least run 3/4"...while you will have the 1/2 restriction at the house, you'll have less resistance to flow over the 430' with 3/4 line.

And while you're only planning on a sink and urinal, you will eventually want a frost proof hydrant outside. At least I did. Might want to put it in now while you have the trencher.

Any chance you could hook to the supply line that feeds your house? It's probably 3/4 or 1", you could tee off of that, put in a below ground shutoff so you could turn the water off going to the shop if you had to.

Fred

 

[Ohmthis]

Yeah, I am a master electrician, so the depth and marker for the power is known. I'm also putting in a 1 1/4 conduit for low voltage. Taking the water to the main would be very difficult, one direction would be to go through a driveway and sidewalk, the other would be taken through rock for about 30'. My plan was to run 3/4, but didn't know if that was a waste of money. Thanks all!

 

[The Cobbler]

400 plus ft has a lot of friction loss. I would even consider 1" for that distance, even though it's being fed by 1/2"

 

[Grayguy]

I'd do 1" PE for a 400ft run. The price difference is marginal

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[Ohmthis]

I have thought about 1" and you are right the difference is pennies a foot for 1" over 3/4". I'm not sold on it being fed by 1/2". I had a burn pile right where my barn sits years ago. I ran several 3/4" hoses together to get water out there in case of emergency. It had pretty good water pressure and flow. Hence my looking at 3/4. Thanks all! If it was feeding a shower or other high use fixtures out there I would be looking at all I could get. But for just a sink and urinal I don't see the need. In the future would a booster pump be an idea?

 

[sberry]

Inch would be cheaper than a booster. You can relate this to electric,,, if you fed this circuit with a few ft of 14 before it left the house a 10 would carry more at 400 ft than a 14 or a 12 regardless of what you fed it with.

 

[Ohio Auto]

I'm not in the business like maybe some of you, but my thoughts are different than what I see posted.

1/2" is going to give you better water pressure, especially going that long of a distance. Water volume as you know cannot be increased by going with a bigger line. I like having good pressure vs. volume as I wash my vehicles and spray down my shop floor with my water supply.

 

[sberry]

Given the same volume the pressure will be better with a larger line, just like an electric wire.

Water volume as you know cannot be increased by going with a bigger line.

How would we get more?

 

[The Cobbler]

I'm not in the business like maybe some of you, but my thoughts are different than what I see posted.

1/2" is going to give you better water pressure, especially going that long of a distance. Water volume as you know cannot be increased by going with a bigger line. I like having good pressure vs. volume as I wash my vehicles and spray down my shop floor with my water supply.

Pressure & volume work together sort of. the longer the run the more "friction loss" you have. so a 1/2" line @ 440' is going to have a lot more friction loss than the same run with a 1" line. the more friction loss, the less volume, as a result the less pressure when the tap is open. at off the pressure will be the same however.

case in point, my home had a 1/2" water service probably 100' from the main line on the street. When the washer was filling, the toilet would barely fill, and if you turned the faucet on at the same time, no water would come out of the faucet.
I replaced the 1/2" line with 1" line up to the meter, I didn't change any inside plumbing and we now can flush the toilet while the washer is filling, and have tons of volume/pressure at the bath faucet.
make sense?
we went from always "limp" water at the hoses & faucets to a good solid stream.

 

[sberry]

You have quite an investment in the rest of it, inch line would give near full service depending on incoming pressure, 3/4 might not be bad depending on that but I live on 250 ft of inch and don't know I am not right at the well. In your garage you want to fill bucket or run a decent pressure washer or water some grass you can.
I have a place I run hand washing from garden hose about 300 ft, it works.

 

[Ohmthis]

Sberry, the the comparison to electric was definitely thought about. I know that if I need a certain voltage and amperage I can calculate what's needed. My problem is I don't know what I need (in psi and gpm). I just know what I'm planning on using. I know I could get the flow numbers of certain fixtures, find out what pressure I have at the 1/2" line in the house and find a calculation, but damn! Thanks a lot everyone!

 

[OccupantRJ]

At the length you are going, I would definitely go with 3/4 or 1". You may want to run a pressure washer out there some day.

 

[Daniel Dudley]

When I ran water, I trenched around to the side of my house where I could access a larger line, and ran 1 inch from 1 inch right past the pressure tank. In my case it was worth it to run an extra 50 feet of trench.

 

[sberry]

Ohm, the calc is very similar and your demands low and you really only need enough pressure to make the water go where you want. Your demand will be low and if its a little slow it probably doesn't make a lot of difference.
The material pricing here is so minor that its worth considering, as you said you are running a single fixture most of the time, its not going to be a deal breaker either way.

I am sure someone has a chart similar to voltage drop tables but its relatively minor considering the load calc. At 200 ft or so a 3/4 still gives fairly respectable service, you are doubling that so a larger pipe isn't severe overkill and an outright waste. 1/2 pipe is similar to 14 in the wiring world.

 

[cdoo932]

You will lose pressure going from 1/2 inch line to anything bigger. Just run 1/2 line the whole way.

 

[J Persons]

I replaced my 75' waterline a couple of years ago, from the meter at the city main to my house, due to low pressure and volume. The original line was 3/4", and it was replaced with 1½" line. They also installed two outside water faucets. I now have lots of pressure and volume. I questioned the 1½" line connecting to a 3/4" line and was assured I would get more pressure and volume. If I wanted a 1½ meter. it would be expensive for the meter, and my water rates would also go up, because the larger meter is considered a commercial meter.

 

[Ohio Auto]

You will lose pressure going from 1/2 inch line to anything bigger. Just run 1/2 line the whole way.

Exactly.

 

[1grnlwn]

With a 1/2" restriction at the house it doesn't make any difference what size pipe you run. Plumbing is all about flow, pressure is irrelevant.

 

[rlitman]

With a 1/2" restriction at the house it doesn't make any difference what size pipe you run. Plumbing is all about flow, pressure is irrelevant.

Couldn't be more wrong. Static pressure is irrelevant, pressure under flow is not, an smaller lines will give greater pressure drop.

 

[1grnlwn]

Ah you win the ******* contest. Must be because of your really small hose.


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[The Cobbler]

You will lose pressure going from 1/2 inch line to anything bigger. Just run 1/2 line the whole way.

With a 1/2" restriction at the house it doesn't make any difference what size pipe you run. Plumbing is all about flow, pressure is irrelevant.

time how long it takes to fill a 5 gallon pail with 400' of 1/2" garden hose hooked to your faucet.
then try the same experiment with 400' of 3/4" or 1" garden hose .
after you've done that, come back & report your findings.
you will find you're wrong...

 

[kaffine]

Looking at pressure drop tables 1/2" PEX pipe has a pressure loss of 5.3psi per 100ft @ 2GPM where 3/4" will only have 1.02psi and 1" would only have 0.35psi loss.

Go up to 5GPM and pressure loss per 100ft is 1/2" 27.4psi 3/4" 5.26psi and 1" 1.58psi per 100 ft.

What is the water pressure at your house?

I would think HDPE pipe would be somewhat close to the pressure losses of PEX the pressure loss tables I found for HDPE weren't in psi and I'm too lazy to convert.

I would go with 1" unless 3/4" is a lot cheaper and I wouldn't consider 1/2" at all.

 

[sberry]

You will lose pressure going from 1/2 inch line to anything bigger. Just run 1/2 line the whole way.

Exactly.

--------------------------------------------------------------------------------

You will lose pressure going from 1/2 inch line to anything bigger. Just run 1/2 line the whole way

Where did you guys learn this?

 

[radrush]

With a 1/2" restriction at the house it doesn't make any difference what size pipe you run. Plumbing is all about flow, pressure is irrelevant.

Couldn't be more wrong. Static pressure is irrelevant, pressure under flow is not, an smaller lines will give greater pressure drop.

1grnlwn = wrong

rlitman = right

1grnlwn has not taken into account friction loss due to the smaller pipe.

If I were you I would absolutely not run anything smaller than 1". But then again there is no way I'd tap into a 1/2" line. I seriously doubt that you are going to be happy with the results if you tap into a 1/2" line.

My 600' water line has a 3/4" tap at the street. Going with the philosophy that anything worth doing is worth overdoing I ran 200' of 2" line, 200' of 1-1/2" line, 150' of 1-1/4" line and then 50' or so of 1" line into the house to the pressure reducer. It steps down to 3/4" after the pressure reducer. Since the water pressure at the street is a good 150psi I get a massive amount of volume and pressure at the house.

 

[Novicaine]

The plumbers ran about 60' of 1" black plastic to my shop hooked into a 1/2" line on the house side -- I have the same volume and pressure as in the house, works just fine. I figure I can always hook into bigger in the house if needed, but it's fine.

 

[Highbeam]

Always use one inch or bigger. It is foolish to save three cents cheaping out on this line. The cost of suffering low performance far exceeds the upsize cost.

Im a civil engineer, i do this for a living. Bigger is better in this case to maximize flow and pressure from the small feed. Heck, a 12 inch main would be better than a one inch. People that think you get less water through a larger pipe are ignorant about the science.

The only reason the string of garden hoses seemed adequate was that your nozzle is an intentional restriction.

 

[1grnlwn]

Since the water pressure at the street is a good 150psi I get a massive amount of volume and pressure at the house.

Congratulations, sounds like you wasted a lot of money on pipe!

 

[Junkman]

Standard rule of hydraulics and flow. Double the diameter, and increase the flow by 4 times. Volume, pressure, and distance are all interrelated, and I don't have the time or patience to start teaching again. Just use the largest diameter pipe that you can reasonably afford, within reason. That means anything between 1" and 2". After that, you are just wasting money.

 

[TK LP]

What is your minimum supply pressure? You may not have any issue to begin with, if your pressure is high enough, the pressure drop may still not impact your usage. Increasing line size will help with pressure loss, but will slow velocity. You could run a 4" fire hose, but with a 1/2" supply, you won't be putting out any fires. Running a 1" poly supply line won't cost much more than a smaller line, so it's probably fine, and if you upgrade later, you're covered, just remember your 1/2" supply is a restriction on your flow. A 1/2" supply is marginal for a urinal, a shower with a modern low consumption water saver head is less demand. For that mater, you could go to a waterless urinal. Typical water closets use tank head pressure to flush, so they require very little pressure, and add versatility. If supply is really and issue, you could also use a well/bladder tank to store pressurized water, which would keep you in water.

 

[sberry]

ve made it possible to use smaller pipes despite numbers of people added to a system. 1/2 was good when it had a greedy 5 gallon fixture on, now it serves 3 fixtures and the shower doesn't scald when the toilet is flushed,,, same pipe, less demand spread out over a bit longer time.
He isn't going to starve service here, not running a household of teenagers constant, itas simpley a matter if a little extra cost is worth it. As you can see the line loss figures someone posted, at 5 gpm almost no real loss with 1 inch and 27 loss with 1/2... this is irrelevant if its fed with 1/2 or not.

Ohm,,, look at long wire feeds, tapps to fit a 60A breaker feeding a 4/0 wire.

 

[Ohmthis]

I think our pressure is ~65-68 psi. The pressure drop chart shows I would lose roughly 1/2 the pressure with 1/2 line. I'm pricing out 3/4 and 1", also try to see if I can snake it through the finished ceiling to the mechanical room where I can access larger pipe. One setback is a fairing tight curve. Thanks for everyone's advice.

 

[sberry]

If the 1/2 run isn't too long your first scheme isn't too bad, if you have 10 ft off 1/2 prior to the connection its ok, 100 ft and it starts to be an issue. You have great water pressure, some loss wont be an issue.