What size sprinkler pump do I need?
A sprinkler pump is like any other pump. It produces pressure and flow. Generally speaking when sprinkling your flow is higher than your home use. There are those times when we want to run a sprinkler with just one hose and move the hose around the yard to where it is needed next. In this case a sprinkler pump is just going to be too big. All pumps have a minimum and maximum flow rate. Most sprinkler pumps have a minimum flow rate of 20GPM’s. So unless you are using 3 or 4 sprinklers at one time the pump will have problems. If you are just going to run one sprinkler on one hose then it would be to your advantage to use a jet pump not a sprinkler. The jet pump will give plenty of pressure and a smaller flow rate that will not hurt the pump.
It would be best to check how much water you need and then pick a pump based on that flow rate. Remember to check the friction loss in your system because it could rob you of needed pressure, (Please read “I don’t have enough pressure”) 23 vertical feet equals 10PSI.
To know your flow rate just look at your sprinkler heads you are using. They should tell you how much water and pressure that are required to make the pattern you are looking for. Multiply the number of heads you will use in each zone by the GPM of each head and that will be your water requirement. Your pressure requirement will be the pressure needed at the head or nozzle, you only have to figure the highest pressure needed by one nozzle, do not add them all up. Add in all appropriate friction losses in the piping system to the farthest sprinkler head. Again you only need to add the longest run of your main line and the longest lateral off that longest run. If the pump can get the water to the farthest sprinkler, all the sprinklers that are close will have more pressure because there will be less friction loss in those zones. And don’t forget your vertical elevation. That is figured from the center of the pump to the highest point you want to pump the water. If you have a lot of elevation you may have to use more water at the lower locations so they do not have too much pressure. The sprinkler manufacture can tell you how much pressure is too much pressure. Too much pressure will cause the sprinkler to mist, if it does not blow the sprinkler head right out of the ground.