If you need a sprinkler pump for your irrigation system, which sprinkler/irrigation pump do you need? A self-priming above-ground pump or a submersible in a well?
This post will help you gather the information you need to choose the right one for your needs. If you have a new installation, this post can provide you with the information needed to get the right pump for the job. If you have an existing sprinkler system and pump, this information will let you know if you have the right pump for your application.
A vast majority of sprinkler systems have undersized pumps that undersupply the correct flow and pressures and give the illusion of working properly by providing the bare minimum of flow and pressure, if at all.
The timer may be the brains of the sprinkler system, but your pump is the heart, and a strong one allows the sprinkler system to operate at peak efficiencies providing a beautiful landscape for years to come.
The information provided assumes the user has a basic knowledge of irrigation, plumbing, and electrical and is intended for residential and small commercial sites.
This information is a basic “rule of thumb” or the minimum or maximum requirements to size a pump. Should you feel uncomfortable with this information and prefer more exact details, don’t hesitate to contact a local pump specialist.
Table of Contents
New Pump Installation
Do you need an above-ground pump or a deep well and a submersible pump?
If you are in an area where shallow wells are easy to do and provide plenty of water, or your property is on a lake or some other water source, then an above-ground pump is a cost-effective option for you. Otherwise, a deep well and a submersible pump will be required.
Replace Existing Pump
Does your existing pump give you the performance it should or that you should have?
If it is about to fail or has failed, you may want to replace the pump with the same model if it has worked well for you. However, many pumps are undersized from day one, providing less than adequate water flows and pressures giving the illusion of proper water application.
Use the sizing information provided to determine if replacing the pump with the same model will work for you or another more efficient model for you.
Locate The Pump For Your Needs
With this information, you can now contact your area pump or irrigation supply house and ask which one they have to suit your needs.
By doing so, you’re using a locally available pump, which means parts are readily available if repairs are ever needed. The pump is easily replaceable if needed. You are using one that will be familiar with local pump service people.
Many manufacturers, choices, applications, and your geographic location can determine which one is best for you.
Area pump supply houses have already learned which one will give you what you need over the years, and knowing this information will stock only a few types to choose from, making the selection process much easier.
You may have to choose from 2 to 3 pumps that are close to your requirements. Which one do you choose?
Look at these three options:
1. A pump at 10% to 20% more GPM and pressure than you need.
2. A pump that pumps close to or exactly what you need.
3. A pump that is just under your GPM and pressure requirements.
If possible, resist the urge to cut corners to save money “today” by getting option two or three. Once you install and begin using the pump, it begins to wear out, reducing its water flow and PSI capabilities.
Within a few short years, it’s performing well below your expectations, your landscaping is suffering, and now your wishing you had the better quality one. Now you have the added expense of replacing the pump with the same one and begin the process all over again, or you put the better pump in.
By getting a pump that pumps a little more water and pressure, you can always throttle back on GPM and pressure, and as the pump wears over the years, you will have an extra performance to use when needed giving you years of extra use and much less worry and aggravation. But if the budget is tight, then option number 2 will be your best choice.
Be aware that horsepower may be misleading. Sometimes going bigger doesn’t always work. Pumps come in three designs… low head, medium head, and high head.
A low head one will pump a lot of water at very little pressure like a pool pump. A medium head one will pump a little less water and little more pressure.
A high head one will pump even less water at much higher pressures as needed for irrigation systems. All three design types could have the same horsepower but provide three totally different performances.
On more than one occasion, we have switched out 2 HP pumps with 11/2 HP multi-stage pumps to get better flow and pressures. Or it may take a 2 HP centrifugal pump to do what a 1 HP submersible was flowing. Sometimes it’s the application that dictates pump size and design type.
Do you get a cast iron or all-plastic pump? Plastic types are usually a lot cheaper than cast-iron types and will perform about the same. But from our experience, plastic pumps, either centrifugal or submersible, have a much shorter life, so we use cast iron pumps for longevity and fewer problems.
New Or Existing Centrifugal Pump Sizing Information
Here are some hard facts you need to know when sizing/picking an above-ground pump of any kind and its location. For best performance, the pump must be located as close to the water supply as possible. The suction side and pipe plumbing of the pump is the key to operating at peak performance.
At sea level, we deal with 14.7 pounds of gravity. When a pump is turned on, it begins to remove the atmosphere inside the suction pipe. As it does, the 14.7 pounds of gravity pressure pushing down on the surrounding water begins to push water up, replacing the atmosphere being removed in the suction pipe.
But there is a limit to how far the water will go up the pipe. For every 2.31 feet (roughly 2 feet and 3 3/4 inches), you lose 1 PSI of gravity force, and that limit is only 33.9 feet mathematically. Still, due to pipe friction losses and pump inefficiencies, the rule of thumb is that 25 feet are the maximum any pump will lift water regardless of other factors. Plus, for every 5 feet of “total suction lift” the pump has to deal with, it loses about 15% to 20% of its discharge GPM.
Another factor to consider is that for every 2000 feet of elevation, you will lose 1 PSI of the 14.7 PSI gravity force. Over 25 feet of lift, they will pump very little if any water and may begin to cavitate.
Cavitation is a process where the water is under enough vacuum force to literally separate itself forming small bubbles that explode in it, making the pump sound like it’s full of rocks.
The pump will never prime or pump water, and if left to run long enough, the cavitation can damage the pump’s internal parts. This calculation applies to all centrifugal pumps, whether the water source is a shallow well, lake, or another water source.
So, the closer we get and keep the pump to water, the more gravity we have and can pump more water and pressure. This is why the suction side of any pump is more important than the discharge side. We can virtually overcome any problem on the discharge side of the pump by sizing the pump accordingly.
Also, gallons per minute (GPM) determines pipe size… not pump taps. Your pump can come with much smaller or larger suction and discharge tap sizes than the pipe needed to meet its GPM flow. Plumb out of those fittings but immediately and within a couple of feet, expand or reduce to the pipe size that meets or exceeds the GPM flow rate.
We recommend using galvanized, brass, or copper fittings from the pump using nipples and bell reducers until you meet your pipe size, then covert over to PVC SCH 40 pipe for all pipe exposed to the elements and once underground, convert to standard PVC or poly pipes.
When pulling water from a lake, shallow well, or another water source, you will need a self-priming pump of some sort. Jet pumps are a good pick for systems requiring low flows such as 5 GPM to about 15 GPM. They provide a steady flow and good pressure. However, most sprinkler systems usually use well above these flow rates.
Our next pick will be self-priming centrifugal pumps. They have large pump bodies to hold their priming water and can pump from 15 GPM to about 45 GPM depending on horsepower (3/4HP to 2 1/2HP) and site conditions. If higher pressures are needed then, multi-stage pumps are a good option within the same horsepower range.
These pumps use two or more impellers to increase flow and pressure, providing 20 to 45 GPM with pressures up to 65 PSI, if not more. 3 HP and 5 HP can provide from 45 GPM to 80 GPM plus.
Once you get into higher flows and/or pressures, we would strongly recommend contacting a pump specialist to assist you in sizing a pump because you will probably need a custom-sized pump for your needs.
- Jet Pumps
- Self Priming Centrifugal Pumps
- Multi-Stage Pumps
- 3 HP and 5 HP Pumps
What To Look For When Buying A Lawn Sprinkler Pump?
When choosing a lawn sprinkler pump, you need to understand that all sprinkler pumps are not created equal. There are many styles and benefits when it comes to owning certain sprinkler pumps, and figuring out the difference between one lawn sprinkler pump and another sprinkler pump can get quite confusing, but lucky for you that you came across this article that will give you some basic and priceless information about some of these sprinkler pumps.
When looking for a water pump for irrigation, you need to remember that different brands carry lawn sprinkler pumps, which are better than others.
Owning a stainless steel lawn sprinkler pump has a huge benefit, and that is it will withstand corrosion, and the durability is usually good when it comes to a stainless steel sprinkler pump.
Another thing you want to look out for when choosing a sprinkler pump is motor size and speed. Obviously, having a better motor in a sprinkler pump will allow it to pump out water faster, and the life span of the pump will be much better than with a lower quality motor.
Some lawn pumps are designed more for just lawns, while others are designed to sprinkle small lakes, ponds, rivers, and such.
The benefits of having a sprinkler pump with a fast and strong moving motor are great because if you are trying to sprinkle a small pond, then a fast and stronger motor will do the job fine. Still, if you want to water a basic lawn, then a simple and basic sprinkler with an average motor will get the job done.
Now there are a few different types of them. For instance, there are pumps installed above ground, and then there are pumps installed underwater, and then there are pumps installed below the ground but have a motor above ground.
Whatever pump you end up getting, make sure that it is durable and will last for quite a while, and don’t sacrifice quality for the price.