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helenawall (Agricultural) (OP)
3 Dec 06 18:33

Hi, I am trying to find out a approximate cost off irrigating 6 acres with well water.
I got a 5g/min pump however i do not know the specs of how much electricity it pulls and i am just looking for a average figure.
Say I need 1 inch/acre = 27154 gal.

How much electricity would a average submersible pump use to pump 27154 gallons and how much would that cost?

Any one that has real life experience doing this that has a similar figure like I spend $x amount of dollars per year
irrigating a 2acre pasture or so pleas feel free to inform me.
gary50 (Mechanical)
6 Dec 06 7:25
The cost of irragation depends on the speed of it. If you use lot of time to pump the wateramount, you need only small pump and cost is low. But if you want to make it very fast, you need big pump and the cost is higher.

Best Regars
Helpful Member!  waross (Electrical)
6 Dec 06 8:36
With the figures that you have given, to pump 27154 gallons per day with a 5 gpm pump, your pump must run 90.5 hours per day.
You may wish to consider a larger pump.
blueoak (Civil/Environmental)
6 Dec 06 10:04
Based on the Nebraska performance data for electricity
water horsepower per hour per kilowatt hour is 0.885
And water horsepower = gallons per minute / 3960 * total head
total pumping head = pressure(psi) + required lift
helenawall (Agricultural) (OP)
6 Dec 06 10:38
Thanks for the reply s I actually typo ed i got a 25galon/h pump.I figure it will take 4.5 days to do the field and it would cost me about $11-15
waross (Electrical)
9 Dec 06 7:43
If you start with a comparison well that is 10 feet deep, it will cost twice as much to pump from a well that is 20 feet deep and 10 times as much to pump from a well that is 100 feet deep.
It depends.
helenawall (Agricultural) (OP)
9 Dec 06 11:14
Thanks for all replys the easiest way to figure out cost is to look at how long it would take to pump amount of water needed to flood field 1 inch, then max energy usage of the pump to operate/pump for that time take that times and what you pay for elect kWh and your done all the other calculations are a waste of time.
helenawall (Agricultural) (OP)
9 Dec 06 11:20
PS.The pump I got is already positioned in the well and the energy it uses is in relation to how deep it needs to be to bring out water (if you would put a inadequate submersible pump in your 4" well you would burn out the motor.)the variables are pointless to pander since it will never use more energy that it can pull.DS
waross (Electrical)
10 Dec 06 1:58
Two things we need to know to help you.
1> What is the cost per kilowatt hour in your area.
2> What is dynamic head.
These parameters will give a minimum energy cost, assuming 100% efficiency. To this we should add about 20% to 30% for real world conditions.
Don't count on a 25 GPM pump putting out 25 GPM under any but design conditions. You have to use the pump curves which are unique to each pump.
Under conditions of increased head, your 25 GPM pump may only deliver 5 or 10 or 12 GPM. You have to check the curve for your particular pump.
BigInch (Petroleum)
30 Dec 06 16:15
Head_feet = (Pd-Ps)*144/62.4
Ps = Suction Pressure PSIG
Pd = Discharge Pressure PSIG

The required hydraulic power is,
Power_ftlbs_per_sec = Head_feet * Q_gpm /7.4805/60

HorsePower = Power_ftlbs_per_sec /550

Power_input_to_pump (Hp)= HorsePower/Pump_Efficiency

Electrical Power required is,
Power_input_to_motor (kW) = 0.746 * Power_input_to_pump/motor_efficiency

multiply your power input to motor by the cost per kWh x the running time.

BigInchworm-born in the trenches.

engineguy2 (Industrial)
15 Jan 07 17:55
I recommend spending the money and using a generous pump to save time, and in the long run, money.

Good Luck.


BigInch (Petroleum)
16 Jan 07 3:08
An oversized pump not only wastes money whenever it runs, but also requires larger pipe diameters and valves.

BigInchworm-born in the trenches.

griffengm (Industrial)
16 Jan 07 7:49
Lessons learned in over twenty years of irrigating small acreage (2-4 acres)
1. If you have a day job, it is difficult to have too large a pump.  Conflicting schedules will inevitably cause the pump to be shut down when it should be running. Extra pump capacity allows the job to be done in a timely manner and when you have time.

2. Regardless of the pump size it is going to go down at the worst possible moment (Corralary to Murphy's law). Larger means you can catch up a little easier when it is fixed.  With irrigation I do not believe there is such a thing as too far ahead.

3.  There is a relationship between distance from dealer/parts and breakdown timing. If your supply source is via the internet, the same lightning strike that takes out your pump will also take out your computer.  Even if the guy down the street is double the internet cost he will be there in spite of the lightning strike.

BigInch (Petroleum)
16 Jan 07 8:06
#1, if you evaluate your requirements and have to pump a certain amount of water in one day and size the pump for that flow, then the pump would not be oversized for that particular application.

BigInchworm-born in the trenches.

blueoak (Civil/Environmental)
19 Jan 07 15:10
The pump sounds fine for sprinklers.

25 gal/hr = 3.34 cu.ft./hr = 0.022 acre inches /day.  It has to be 25 gpm or 1.32 acre inch/day.
I do not know your climate, but if don't have summer rains you need to be able to irrigate at about a minimum of 80% of your peak ET unless you don't mind losing fall growth a lot.  
So your peak ET is probably somewhere near 0.3 in/day for grass (depending on location normally 0.25 to .35). Check your efficiency.  For sprinklers about 80% if you did a good job, I like 70% for older or if you have cows walking around(they cosntantly break sprinklers).  If you get donuts of green grass drop it another 5%.  Also 2 acres is small so if you are going to run any animals on it you also need to factor in some days without water so you don't compact the ground too much.  If it just for hay give yourself 1 day in 10 for breadowns.

Overall a good flowrate for your situation depending on pressure at 25 gpm.  I would think you could automate it and run 4 zones.  If you are good with the nozzles you choose you might even get away with ag use times (at night) and save some money.

Reading over the comments I think you may have the head required wrong.  You also have to run the sprinkler at about 60 ft of head.  With inlet losses it was hard to get a good system with less than a 70' vertical drop.  Check with Rainbird or Toro specs.

Of course, if you are flooding this all goes out the window.  For flood you need the head of a large stream of water to get the water across the field.  Pasture is hard to flood with small constant streams, ie 3 days on and 3 days off on irrigation ditches.  The people I have seen trying to flood small pastures get about 40% with a lot of water weeds.  I would be interested in how you are going to irrigate if it is flood, basin, border, corrugations, or wild land.

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