Here’s the basic procedure to follow if you’re trying to find the right pump horsepower and model for a new irrigation system. You’ll probably want to refer back to this list as you learn more.
Related how-to pump articles:
How to Select a Replacement Pump For An Existing Irrigation System.
How to Select a New Pump for an Existing Irrigation System.
How to Design a New Irrigation System to Use wit an Existing Pump.
How to Improve the Performance of an Existing Pump.
How to Select a Pump for a Rainbarrel.
1. Research the Water Supply Limitations and Laws.
Find out if there are any limiting issues for your water supply capacity. You need to find out if there are any flow issues that might cause your pump to “run dry” or use up all the available water. A pump can be severely damaged if it runs dry (no water.)
Examples: if pumping from a stream or lake there may be only a limited amount of water you can take without pumping the water source dry! There may also be legal restrictions on how much water you can take, especially from creeks or streams, you should check to make sure. You don’t want to buy an expensive pump only to have the Fish and Game Department or EPA order you to remove your pump because it is endangering some fish, or frog, or whatever. Make sure you have the proper permits to take the water!
Another example: in some locations wells have very limited capacity due to lack of groundwater. This is really common in areas with underground granite rock formations, like in the western mountains of the USA. If you plan to use a well for the water supply but haven’t drilled it yet, talk to an experienced well driller in your area for help with determining the likely capacity of a well at your location. It is strongly recommended that you drill the well and test the capacity before you design the irrigation system or buy a pump! The well driller will install a temporary pump to test the well capacity.
2. Learn About Pumps.
Learn about pumps by studying these two pages:
The above two pages are the core of this tutorial. They contain all the information you will need to know to pick the best pump for your system.
3. Create Your Irrigation Design.
Create an irrigation design or have someone make one for you. Way too many people run out and buy a pump at this point, often because they see one on sale, and then they try to design the irrigation to match the pump. That is possible to do, but it is not the best way and will almost always result in problems and substantial extra expenses. Design your irrigation system first, then get a pump with the capacity to operate it. Once you have designed your irrigation system you will know the exact flow and pressure it requires and can buy the right pump. The Irrigation Design Tutorial on this website will guide you step-by-step through the design process. Unlike most irrigation design tutorials this one goes into detail on the unique design requirements for irrigation systems that use pumps.
Once you know the exact pressure and flow requirements of your irrigation system you can research the available pump models and select a preliminary pump model that meets the requirements you established above.
At this point go back and take another look at your irrigation design. You might wish to make minor changes to the irrigation system design based on what you now know. You will have learned a lot more at this point than you knew when you started! Usually all is good at this point. But sometimes you will discover that a minor tweak of the irrigation design would allow the use of a less expensive or more efficient pump, and it might be worth making the change while it is still only a change on paper.
4. Start Shopping!
Once you have completed all the above items you can pick out a great pump for your system and buy it.
Yes, this method of selecting a pump requires considerable up-front effort! However, it will give you an excellent balance between pump and irrigation, leaving you with a very efficient irrigation system! The pump is a major part of your system and a good pump is not cheap. It should work efficiently to save you money day-after-day, and provide many years of trouble-free service. Remember that a little up-front time invested is likely to save you money for years to come.