Help! Math test on water pumping costs

[Ballvalve]

Problems with a well share- nasty neighbors. They are complaining they are not getting enough $ for the gallons of water pumped. Cost is only for the electrical cost per gallon pumped.

1 hp submersible pump producing 500 gallons per hour. I used 3 KW per hour [which I think is generous] at .13 cents per KW = .39 cents. .39 Divided by 500 gallons = .00078 cents per gallon.

Is this math correct? Sure seems like it to me, but since we are heading to lawyers, would love to have my head checked. On my posting this question in 2012 Valveman answered with a even lower figure.

So if I used 10,000 gallons of water, x .00078 cost would be $7.80

I know we have many other variables - efficiency, pumping water level, pressure level [head] at shut off, type of pump, csv or pressure tank or cistern. There are some crazy complicated calculators out there on the web. What would you use as a general number?

 

[Valveman]

If you had all the figures to do a wire to water efficiency, you could be more exact. But volts X amps = watts. A 1HP pulls 9 amps max at 240 volts. That is 2160 watts, or 2.16KW. At 13 cents a KW that would be 28 cents per hour. With a flow rate of 500 GPM per hour, 56 cents per 1000 gallons would be the pumping cost.

 

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[Texas Wellman]

Valveman how do you rectify those numbers with the ones given by franklin's AIM of 1200 full load watts and 1600 maximum watts? I thought that due to the power factor that it wasn't a straight calucaltion V x A = W?

 

[Valveman]

My old AIM manual shows 1700 watts at SF amps, but I don't know how they get that number. V x A x PF is more correct, but 9 x 240 x .9 is still 1944 watts. Maybe they are using 220 volts and 8 amps with a PF of .97. But you know a 1HP sub pulls 9 amps at 240 volts.

 

[Reach4]

You could wire in a watt-hour meter if there is skepticism. You can search for watt hour meter on an auction site.

 

[Ballvalve]

Thanks for the help!