How Do You Prime a Sprinkler Pump? Pump Priming Tutorial

Introduction

If you’ve ever turned on your sprinkler system only to find weak or no water flow, you may have asked yourself, “How Do You Prime a Sprinkler Pump?” Priming is a simple, essential maintenance task for most residential and commercial sprinkler systems that use centrifugal pumps. It involves filling the pump casing with water to remove trapped air, allowing the pump to create the suction needed to move water from your source (well, pond, or cistern) to your sprinklers. Without proper priming, your pump will run inefficiently, lose pressure, or even suffer permanent damage from running dry. This comprehensive tutorial will walk you through everything you need to know about sprinkler pump priming, including when to do it, the tools you’ll need, step-by-step instructions for different pump types, troubleshooting tips, and best practices to keep your system running smoothly all season long.

• What Is a Sprinkler Pump and Why Does It Need Priming?
• When Do You Need to Prime a Sprinkler Pump?
• Tools and Materials You’ll Need for Pump Priming
• Step-by-Step Guide: How Do You Prime a Sprinkler Pump?
• Priming a Centrifugal Sprinkler Pump
• Priming a Submersible Sprinkler Pump
• Comparison: Common Sprinkler Pump Types and Priming Requirements
• Tips and Best Practices for Successful Pump Priming
• Common Mistakes to Avoid When Priming a Sprinkler Pump
• Troubleshooting Priming Issues
• Frequently Asked Questions
• Conclusion

What Is a Sprinkler Pump and Why Does It Need Priming?

A sprinkler pump is a specialized water pump designed to move water from a source (such as a well, pond, rain barrel, or municipal supply) to your lawn or garden sprinkler system at the pressure needed for even coverage. The most common type of residential sprinkler pump is the centrifugal pump, which uses a rapidly spinning impeller to create centrifugal force that pushes water outward through the discharge pipe.

How Sprinkler Pumps Work

Centrifugal pumps cannot pull air, only water. When the pump casing is empty of water and filled with air, the impeller spins freely without creating enough suction to draw water from the source. Priming fills the pump casing and the suction line (the pipe that draws water from the source to the pump) with water, eliminating all trapped air. Once the casing is full of water, the impeller can create the suction and pressure needed to move water through the entire sprinkler system. Submersible pumps, by contrast, are installed directly in the water source, so they are always fully submerged and do not require priming under normal conditions.

When Do You Need to Prime a Sprinkler Pump?

You will need to prime your sprinkler pump in several common scenarios, most of which involve air entering the pump casing or suction line:

• After installing a new pump or system: New installations often have trapped air in the pipes and pump casing from the manufacturing and installation process, requiring priming before first use.
• After a prolonged power outage: If power is lost for more than a few hours, water can drain back from the system into the source, leaving air in the pump and suction line.
• After seasonal shutdown: If you turn off your sprinkler system for winter, the pump will lose prime when you restart it in spring, as water drains from the lines and casing.
• If there is a leak in the suction line: Even a small crack or loose fitting in the suction pipe can let air into the line, causing the pump to lose prime over time.
• If the pump runs but no water comes out: This is a clear sign the pump has lost its prime and needs to be refilled with water to restore suction.
• If the pressure tank is empty or not building pressure: A drop in pressure tank water levels often indicates the pump has lost prime and is not refilling the tank as it should.

Tools and Materials You’ll Need for Pump Priming

Priming a sprinkler pump requires only a few basic tools and materials, most of which you likely already have around the house:

• Garden hose with access to clean, potable water: Used to fill the pump casing with water and expel trapped air.
• Adjustable wrench or screwdriver: To remove and replace the priming plug on the pump casing.
• Plumber’s (Teflon) tape: To seal the priming plug and suction line connections, preventing air leaks that will cause the pump to lose prime quickly.
• Clean bucket: Optional, useful for catching water when removing the priming plug, or for holding water if your garden hose cannot reach the pump.
• Funnel: Optional, helpful if your pump’s priming port is small and a standard garden hose does not fit snugly.
• Clean rag: To wipe up spills and dry the priming port before replacing the plug.

Step-by-Step Guide: How Do You Prime a Sprinkler Pump?

The following steps work for most centrifugal sprinkler pumps, the most common type that requires priming. Always consult your pump’s user manual for model-specific instructions before starting.

1. Turn off power to the pump at the breaker box. This is a critical safety step that prevents the pump from accidentally turning on while you’re working, which could cause injury or damage to the pump. Lock out the breaker if you have small children or pets nearby to prevent accidental activation.
2. Locate the priming port on your pump. This is usually a small, threaded plug on the top or side of the pump casing, often labeled “Prime” or marked with a prime symbol. If you cannot find it, refer to your pump’s user manual for the exact location.
3. Close the discharge valve that leads to your sprinkler system. This valve is typically located on the pipe exiting the pump and leading to the pressure tank and sprinklers. Closing it prevents the water you add to the pump from flowing out into the system before the pump is running.
4. Remove the priming plug using your wrench or screwdriver. Place your rag under the plug to catch any residual water that may drain out. Inspect the plug and the port for debris or damage, and wrap the plug’s threads with fresh plumber’s tape if the old tape is worn.
5. Connect your garden hose to a clean water source, and insert the free end into the priming port. If the port is too small for the hose, use a funnel to direct water into the port without spills.
6. Turn on the water supply slowly. Let water flow into the pump casing until you see water start to overflow out of the priming port. This indicates the casing is full of water and all trapped air has been expelled. For pumps with long suction lines (over 25 feet), you may need to let water run for 5 to 10 minutes to fill the entire line.
7. Turn off the water supply, remove the hose or funnel, and quickly replace the priming plug. Tighten it securely with your wrench or screwdriver, but don’t over-tighten, as this can damage the threads. Wipe away any spilled water with your rag.
8. Open the discharge valve slowly to allow water to flow into the pressure tank and sprinkler lines.
9. Turn the power back on to the pump at the breaker box. Let the pump run for 1 to 2 minutes to build pressure in the system. You’ll hear the pressure tank’s pressure switch click off once the system reaches the set pressure (usually 40-60 PSI for residential systems).
10. Check your sprinkler heads to confirm water is flowing properly. If water is sputtering or not coming out at full pressure, turn off the pump, re-prime it, and check for leaks in the suction line.

Priming a Centrifugal Sprinkler Pump

Centrifugal pumps are the most common type used for residential sprinkler systems, and they require priming any time air enters the casing. If your centrifugal pump has a foot valve (a one-way valve installed at the bottom of the suction pipe, near the water source), this valve will hold water in the suction line between priming sessions, reducing how often you need to prime. To check if your foot valve is working, turn off the pump, remove the priming plug, and see if water flows out of the port. If water flows out freely, the foot valve is holding water as it should. If air comes out, the foot valve is damaged and needs to be replaced. For centrifugal pumps with long suction lines, you may need to prime the pump twice to fully fill the line with water and remove all trapped air.

Priming a Submersible Sprinkler Pump

Submersible sprinkler pumps are designed to be installed directly in the water source (well, pond, cistern), so they are always fully submerged in water and never require priming under normal operating conditions. However, there are a few scenarios where you may need to bleed air from the system: if the water source ran dry and air was drawn into the suction line, if the pump was removed for maintenance and reinstallation, or if there is a leak in the discharge line that let air in. To bleed air from a submersible pump system, turn off power to the pump, open the drain valve on the pressure tank, and let water run until it flows steadily without sputtering. Close the drain valve, turn the power back on, and let the pump run until the pressure tank refills. If your submersible pump is constantly losing pressure or requiring bleeding, it may be installed too high above the water table, or the check valve may be faulty. Consult a professional to adjust the installation or replace the check valve if needed.

Comparison: Common Sprinkler Pump Types and Priming Requirements

Not all sprinkler pumps require priming, and the type of pump you have will determine how often you need to perform this maintenance task. The table below compares common sprinkler pump types and their priming requirements:

Tips and Best Practices for Successful Pump Priming

Following these best practices will make priming easier, reduce how often you need to do it, and extend the life of your sprinkler pump:

• Always turn off power to the pump at the breaker before starting any maintenance, including priming. This prevents accidental startup and reduces the risk of electric shock.
• Use clean, potable water to prime your pump. Dirty or sediment-heavy water can clog the pump’s impeller, reduce efficiency, and cause premature wear on internal components.
• Inspect the suction line for leaks before priming. Even small cracks or loose connections can let air into the line, causing the pump to lose prime quickly after startup. Wrap suspect connections with plumber’s tape and tighten fittings as needed.
• Replace the plumber’s tape on the priming plug and suction line connections every time you prime the pump. Worn tape can create small gaps that let air in, leading to frequent priming needs.
• Prime your pump at the start of each irrigation season, even if it held prime over the winter. This ensures the system is full of water and ready to operate at full pressure.
• Keep a log of how often you need to prime your pump. If you find yourself priming more than once a month, there is likely an underlying issue (leaky suction line, faulty foot valve, incorrect installation) that needs to be addressed to avoid damaging the pump motor.
• If you have a well with high sediment content, use a fine-mesh filter on your priming hose to prevent debris from entering the pump casing during priming.
• Never overfill the pump casing when priming. Once water starts overflowing from the priming port, turn off the water immediately to avoid spills and excess pressure in the system.

Common Mistakes to Avoid When Priming a Sprinkler Pump

Avoiding these common errors will save you time, prevent damage to your pump, and ensure your sprinkler system works reliably:

• Forgetting to turn off power before priming: This can cause the pump to start unexpectedly while your hands are near moving parts, leading to injury. It can also damage the pump’s motor if it runs dry while the priming port is open. Always shut off power at the breaker and verify it’s off with a voltage tester before starting work.
• Not closing the discharge valve before priming: If the discharge valve is open, the water you add to the pump will flow out into the sprinkler lines instead of filling the pump casing, leaving air trapped inside. Always close the discharge valve before adding water to the priming port.
• Over-tightening the priming plug: Overtightening can strip the threads on the pump casing, leading to leaks and air entering the system. Tighten the plug firmly, but stop if you feel resistance to avoid damaging the threads.
• Using dirty or contaminated water to prime: Sediment, chemicals, or debris in the priming water can clog the impeller, damage seals, and contaminate your irrigation water, harming your lawn or garden. Always use clean, potable water for priming.
• Ignoring frequent priming needs: If you have to prime your pump more than once a month, there is likely a leak, faulty foot valve, or installation issue. Ignoring this will cause the pump to run dry frequently, leading to motor burnout and costly repairs. Address the root cause as soon as possible.
• Priming the pump with the suction line above the water source: The suction line must be fully submerged in the water source at all times to prevent air from entering. If the end of the suction line is above the water level, air will be drawn into the line, making priming impossible. Ensure the suction line is installed below the lowest water level of your source.

Troubleshooting Priming Issues

Even with proper technique, you may run into issues when priming your sprinkler pump. Here are solutions to the most common problems:

• Pump won’t hold prime after priming: First, check the priming plug to make sure it’s tightened securely and sealed with plumber’s tape. Next, inspect the entire suction line for leaks, cracks, or loose connections. If the suction line is intact, check the foot valve (if installed) to make sure it’s not stuck open or damaged. Replace the foot valve if it’s faulty.
• Pump runs but no water comes out: Check if the water source (well, pond, cistern) is low or empty. If the source has water, inspect the suction line for clogs or blockages. If the line is clear, the pump’s impeller may be clogged with debris – turn off power and remove the pump to clean the impeller.
• Water spits out of the priming port when trying to prime: This means the pump is already partially primed, or there is a blockage in the discharge line that is preventing water from flowing out. Close the discharge valve fully, and try priming again. If the problem persists, check the discharge line for clogs or closed valves.
• Pump makes a loud grinding or screeching noise after priming: This is a sign the pump is running dry, or the impeller is clogged or damaged. Turn off power immediately to avoid burning out the motor. Inspect the suction line for air leaks, check the impeller for debris, and re-prime the pump if needed.
• Pressure tank won’t build pressure after priming: Check the pressure switch to make sure it’s set correctly and functioning. If the switch is working, the pump may not be producing enough flow due to a clogged impeller, a leak in the discharge line, or a faulty check valve. Inspect each component and replace as needed.

Frequently Asked Questions

How often should I prime my sprinkler pump?

Most well-maintained centrifugal sprinkler pumps only need priming once a year, before the start of the irrigation season. If you need to prime it more than once a month, there is likely a leak in the suction line, a faulty foot valve, or the pump is installed too high above the water source. Address these issues quickly to avoid damaging the pump motor.

Can you run a sprinkler pump without priming it first?

No, you should never run a centrifugal sprinkler pump without priming it first. Running dry will cause the impeller to overheat, seize up, and burn out the motor, leading to expensive repairs or a full pump replacement. Submersible pumps do not require priming, as they are fully submerged in water during operation.

What does it mean to prime a sprinkler pump?

Priming a sprinkler pump means filling the pump casing and suction line with water to remove all trapped air. This allows the pump’s impeller to create suction and move water through the system to your sprinklers. Without priming, air in the pump will prevent it from generating the pressure needed for irrigation.

Why does my sprinkler pump keep losing prime?

Common causes include leaks in the suction line, a damaged or stuck foot valve, a loose or unsealed priming plug, or the pump being installed higher than the recommended distance above the water source. Check each of these components first if you find yourself priming the pump frequently.

Can I use antifreeze or other liquids to prime my sprinkler pump?

You should only use clean, potable water to prime your sprinkler pump. Antifreeze, chemicals, or other liquids can damage the pump’s internal components, contaminate your irrigation water, and harm your lawn or garden. If you live in a cold climate and need to winterize your system, follow the manufacturer’s winterization instructions instead of using priming liquids.

How long does it take to prime a sprinkler pump?

For most residential centrifugal sprinkler pumps, priming takes 5 to 10 minutes. If you have a long suction line or a lot of air in the system, it may take up to 15 minutes. Submersible pumps do not require priming at all, so the process takes no time for those systems.

Conclusion

Priming a sprinkler pump is a simple, low-cost maintenance task that can save you hundreds of dollars in pump repairs and keep your irrigation system running at peak efficiency all season long. Whether you’re dealing with a standard centrifugal pump for a residential lawn or a submersible pump for a deeper well, understanding how to prime your system correctly will ensure you never face a dry, brown lawn due to pump failure. We covered the key steps for priming, the differences between pump types, best practices to avoid common mistakes, and troubleshooting tips for when things go wrong. If you ever find yourself asking “How Do You Prime a Sprinkler Pump?” again, refer back to this guide to get your system up and running in minutes. With regular maintenance and quick attention to priming issues, your sprinkler pump will last for years, keeping your lawn, garden, and crops healthy and hydrated.