Monthly cost of running a pump?

To calculate the cost of running the pump you would like to install use one of the following formulas:


  • WATTS 
    If the pump is rated in watts use this formula: 

    ​Pump wattage divided by 1,000 x cost per kilowatt hour x hours in a day x 30.4 (billing days each month) = Cost per month to run.    ​ 

    So if I have a pump that uses 300 watts and my electricity costs $0.15/kWh the formula would look like this:

    300 / 1,000 x 0.15 x 24 x 30.4 = $32.83 a month to run.


  •  AMPS
    If the pump is rated in amps use this formula:

    ​Pump amps x volts divided by 1,000 x cost per kilowatt hour x hours in a day x 30.4 (billing days each month) = Cost per month to run.

    So if I have a pump that uses 3 amps and my electricity costs $0.15/kWh the formula would look like this:
    ​
    3  x 120 / 1,000 x 0.15 x 24 x 30.4 = $39.39 a month to run.

​

  • Not all pumps are created equal. A pump that
    will move 3,900 gallons in an hour could cost
    ​you as little as $16/month to run or as much as $90/month to run so shop around and pay close attention to the watts or amps that a pump uses. The cheapest pump is not always the best and a pump that costs a little more to buy will save you thousands of dollars over the life of the pump in electrical costs alone.

POND CONSTRUCTION

The most important thing to take into consideration is the amount of water you want to move. For the health of the pond you need to change or cycle the entire pond every hour. This means if you have a 500 gallon pond you need a 500 gallon per hour (gph) pump to circulate the water. If you want to have a stream or waterfall this is not sufficient. A simple ratio to figure out the size of pump you need is: stream width x desired depth of the water in the stream x 50. For example, if I want an 18 inch wide stream, 2 inches deep the calculation looks like this: (18x2) x 50 = 1800 gph. This leads you to the next question. Which type of pump should I buy, an out of pond pump or an in pond or submersible pump? Do not buy a swimming pool pump or a Jacuzzi pump they are inefficient and will cost a lot of money to run.

Submersible pumps are the least 
expensive to buy, but the most 
expensive to run. A 3900 gph pump you
can buy at Home Depot will cost you 
 around $250 to buy. It will use about 
 700 watts of electricity. There are new 
 generation pumps that will use 175 watts
​ of electricity and pump 3900 gph - they 
​cost $350 and up. Inexpensive submersible pumps also clog easily since they have a built in screen to keep leaves and other junk out. More expensive pumps will not have the built in screen and can suck junk up to 1 inch in diameter through them. They do have advantages compared to centrifugal pumps in that they are quiet since they are in the water you will not hear them.

​Centrifugal or out of pond pumps 
start around $350, but they run on 
less electricity and pump more 
water. They last longer and have 
fewer mechanical problems as well. These pumps will pump up to 10,000 gph. These type of pumps may produce a slight whining sound as they run, so keep them as far away from areas that have seating for pond enjoyment. Do not forget about running electricity to the pumps. It would be smart to run the wire in 1/2 inch PVC electrical conduit piping so later you do not accidentally cut into the wire and electrocute yourself. Place the GFCI outlet in a water resistant enclosure 3-6 feet from the pond and at least 1 foot above the ground. Check with your local city codes for exact requirements.


On average, plan on replacing the pump every 5 years if you are running it 24 hours/day all year.