This post was originally published last April. Since we received so many good comments on it at the time, we thought it was worth a repeat, in case you missed it the first time.
Here’s a question that more of us should know the answer to. How much water can you get for $1?
With a submersible water system, it’s easy to figure out. We just need to know 3 things:
- The GPM delivered by the pump
- The power consumption of the motor
- The price of electricity
For our example, we’ll use the most common unit in the United States, a ½ horsepower, 10 GPM pump. We can ignore whether it’s 2- or 3-wire, since the power consumption is identical for both units.
From page 13 of the Franklin Electic AIM Manual, the power consumption of a ½ hp motor is 0.96 kilowatts. But, we pay for electricity in terms of kilowatt-hours. That is, the number of kilowatts multiplied by the number of hours we used those kilowatts. So, if we run that ½ pump for 1 hour, we’ll consume 0.96 kilowatt-hours (0.96 kilowatts x 1 hour).
According to the latest figures from the US Department of Energy, the average retail price of electricity in the US is 9.7 cents per kilowatt-hour. To keep the math simple, we’ll just round that to 10 cents.
So, putting it all together, if we run that pump for 1 hour, we’ll pay:
0.96 kilowatt-hours x 10 cents per kilowatt-hour x 1 hour = 9.6 cents
To get to $1, we would need run the pump about 10.4 hours:
0.96 kilowatt-hours x 10 cents per kilowatt-hour x 10.4 hours = $1.00
That 10.4 hours converts into 624 minutes (10.4 hours x 60 minutes). With our 10 GPM pump, that would mean 6,240 gallons for a dollar.
So, for $1, we provided over 6000 gallons of cool, clean, fresh well water. You can run the same exercise with different ratings of motors and pumps. But, no matter what, your customers will never find a better deal anywhere.