Not sure what you elevations are but at 550' it is the friction loss of the pipe that will cause the problem.

Lets say you want 15 GPM. (I picked that because I doubt you well pump would exceed that)

Not accounting for fittings or elevation, hereÂs what you would have:

3/4" - 49' of friction loss per 100' pipe
Thus you would have no water with 3/4" pipe!

1" - 15' of friction loss per 100' pipe
Unless you start with about over 95 PSI, again no water or only a trickle!

1-1/4" - 3.5' friction loss per 100' pipe
About a 20 PSI drop without accounting for ftgs or elevation

1-1/2" - 1.75' friction loss per 100' pipe
About a 10 PSI drop without accounting for ftgs or elevation

1-1/2" poly pipe should be your choice depending on your available pressure. You may wish to consider 1-1/4" and repump/pressurize out in the barn. Add in a rise in elevation and these numbers are skewed immensely. Then you may be looking at 2" and re-pumping.

Good thing you asked, many people make this mistake and find out later that they have no water or usable pressure once pipe is laid and buried.

I did not check the facts used for the above post. When no water is flowing, the pressure at the destination will be the same as at the source- if the elevation is the same. Pressure losses will occur because of increased elevation at the destination. If this is not your situation, the pressure loss will occur while water is flowing. But some water will be available at the destination. Pressure loss due to friction may sharply reduce the flow rate. If you wish to only fill a watering trough, the 3/4" should do the job.

A Little Giant 3/4" lawn hydrant has a flow rate of 20gpm @ 60-85psi.

20gpm exceeds the maximum allowable flow velocity for 3/4" or 1" pipe.

At 20gpm the minimum allowable pipe size is 1-1/4" and that would have a friction head loss of 2.59psi/100' of pipe.

With a 550' run the friction head would be 5.5 x 2.59psi = 14.245psi friction head loss plus whatever the Vertical head loss or gain is for change in terrain elevation

Increasing the pipe to 1-1/2" would reduce the friction loss to 1.22psi/100ft

I shot from the hip on my numbers but looks like lazy pup is right assuming the installer doesn't use a bunch of insert couplings to get there. My numbers are probably closer to sch 40 PVC losses.

Found my chart for poly:

3/4" 160# poly pipe with no fittings is 85.2225# loss in 550'

1" 160# poly pipe with no fittings is 25.1605# loss

I dont get it bus driver, the purpose of the long run of pipe is to flow water thus after a gallon the water flow will drop off to nothing on 3/4".

A rated flow of a faucet does not necessarily mean that the flow rate will be that much anytime water is drawn from that faucet (or hydrant). For example, your kitchen faucet might be rated at 2.2 gpm. But in your typical use, you might use it at a lower flow rate by opening it only partially. Pressure losses in piping due to friction are dependent on the flow rate. The cited friction losses will be less at lesser flow rates. I own a house , 2 1/2 baths, supplied by more than 700' of 1 1/4" black poly pipe. The source is at 50 psi, a well pump. The house is about 10' lower than the pump storage tank. The water pressure and supply at the house is very satisfactory. I heartily endorse using calculations to predict outcomes. But interpretations of those calculated results is also important.

I would expect a barn with water troughs will require a significant flow, more than to wash hands being he is hinting he has animals and other purposes for a significant flow such as washing. That was my sole meaning

The 10' drop is definitely an advantage for you bus driver.

The proper method of sizing the line to his barn is to begin with the number of cattle, horses or other livestock then check the livestock demand tables to determine how much water is required daily for each animal. By example a riding horse requires 25-30gal/day but a milk cow requires 35-45gal/day.

In respect to Bus drivers comments I would agree that is highly unlikely to happen, but for the sake of design we are required to design for the worst case scenario.

When designing the main water supply line to a structure we are required to first compute the total load for the structure based upon fixture demands listed in the code.

For illustration I have worked up the total demand for your house as follows:

Bath #1
Lavatory 2gpm 8psi
W.C.(tank type) 3gpm 8psi
Bathtub 4gpm 8psi

Bath #2
Lavatory 2gpm 8psi
W.C.(tank type) 3gpm 8psi
Bathtub 4gpm 8psi

½ bath
Lavatory 2gpm 8psi
W.C.(tank type) 3gpm 8psi

Kitchen
Kitchen sink 2.5gpm 8psi
Dishwasher 2.75gpm 8psi

Laundry Tub 4gpm 8psi

Hose bibb 5gpm 8psi
Total load 37.25gpm 8psi

It must be understood that if the velocity of flow exceeds certain specified limits there is a high risk of premature pipe failure from excessive pipe wall erosion therefore the pipe friction loss tables are clearly marked to show the maximum flow rate for each size of pipe. 1-1/4" PE-SDR pipe is limited to a maximum of 20gpm.

I would wholeheartedly agree that it is very unlikely that you would ever run all the fixtures simultaneously, but that is not an impossibility so for the sake of argument let us examine the outcome if you were to run all fixtures in your house simultaneously.

At 37.5gpm the velocity of flow in your 1/1-4" pipe is 8.025fps and the "friction head loss" is 8.23psi/100ft x 700 feet = 8.23 x 7 = 57.61psi loss. On the other hand, because of the drop in elevation from the pump to the house you gain 10 of vertical static head, which is 4.34psi so the actual pressure loss is 57.61psi 4.34psi = 52.97psi, therefore to meet code minimums you would have to run your pump with a cut-in pressure of 60.97psi and with a typical 20psi differential the cut-out pressure would then be 80.97psi. Keep in mind that code maximum for a potable water system is 85psi therefore if this were a 2 story house you would not have sufficient water pressure to push the water up to the second floor..

Taking this discussion to the next level, while your house is 10ft below the level of your pump your ground floor is no doubt slightly higher than average terrain at the house location and your shower head is 6 higher than the ground floor, therefore the shower head is probably not more than a few inches below the level of the pump and you get no vertical static head gain.

Per code specification we would be required to run a 2" line for your house.

As I stated in the beginning, when designing the water supply & distribution system we are required to compute for a 100% load on a Single Family Residential Structure.

For Multi-Family Residential Structure (Greater than one but not more than four dwelling units and not to exceed three stories in height) we first compute the total demand for each dwelling unit then we may use 80% individual unit demand to compute the aggregate total demand load for the structure.

For a Commercial Residential Structure (Five or more dwelling units and may exceed 3 stories in height) we compute the load for each dwelling unit, then we use 60% of the individual dwelling unit demand to compute the aggregate total load for the structure.

Interesting post by lazypup. That system would perform wonderfully. It assumes continuous flow rates for water usage. To digress slightly, it brings to mind how much codes can hamper those of limited financial means. Comply with code or do without. On a practical note, if one had a similar situation where the pipe is already installed and proves to be only marginally adequate AND the use of water is sporadic, a bladder-type storage tank could be used near the point-of-use. It would fill to system pressure, with elevation affecting that pressure, and the drawdown capability of that tank would be available exclusive of the friction pressure loss of the supply to the tank. Freeze protection, if needed, would be required.

Busdriver

Your bladder tank mention brings up memories

I remember as a young man starting out I cared for a 4 story commercial building. The flushometers on the 4th floor didnt work. We had good pressure/no volume

To fix quotes were to:

1. Repipe (remove galvanized)
2. Booster system (Afraid of old piping problems)
3. Remove urinals and toilets and install tank type

Well with no $ available, I installed a 10 gallon drawdown bladder type well tank in the closet behind the restrooms and all was well

Made me a 22 year old hero.

In the original post "Barnfield" is asking what size of line he needs to provide water to his barn and pasture area.

To properly answer the question we would need to know the number and type of animals in the barn or pasture then we would need to consider the drinking habits of the animals themselves.

By example, if we were supply water for milk cows we would need to provide 35 to 45gal per cow per day, therefore if we had 10 cows we would need to provide 450gal/day.

We must then consider the drinking habits of the cows. By example, if we place a watering tank in the pasture we would need a 450gal tank to provide a full days supply of water and theoretically we could allow the water to run continuously for the 24 hours so we only need 0.3125gpm. In this case we could run a 1/2" line and use a toilet ballcock to control the level of the water in the tank, however stock watering tanks are fairly expensive so typically they would use a 100 or 150gal tank.

Research has shown that cows are herding animals and individual animals seldom venture more than 250 feet from the group therefore if the water tank is more than 250 feet from the primary grazing location the cows tend to wait until the entire herd is ready to go to the water at the same time, and under these circumstances they tend to make the trip to water about 2 times a day. The problem here is that each cow consumes 35-45gal/day so they will each consume about 17.5-22.5 gal on each trip to the water and they tend to only remain at the water location about 30 minutes before returning to the grazing area. In addition, cows do not drink water at night so we must plan on them drinking in the morning then returning in mid to late afternoon. In this scenario we would need a 225gal tank and a water supply that could fill that tank in about 8 hours. If we were to still allow the water to run continuously we could get by with a water supply that provides 0.468gpm, and here again we could set up an automatic watering system with a toilet fill valve or we could use a manually controlled hydrant and stand there waiting 10 - 15 minutes for the tank to fill.

However, there is another factor relating to the habits of the animals that we must consider. If we install a tank and water supply that can only meet the need at the individual drinking times, the water level in the tank will drop extremely low before all the animals have opportunity to drink. As the water level drops, the cows sense that as a limited supply of water and they tend to drink a considerable amount more than they actually need. The end result here is a high stress level on the herd because the stronger animals push into the water first and they drink more than they really need so there is a very limited supply to the younger and weaker animals that get to the tank last.

The solution is to place the tank were it is located within 250 feet of the primary grazing area, then each animal feels comfortable to wander over to the water tank whenever they are thirsty and there is never a crowd of animals competing for the water.

MOOOOOOO!