How to Prime a Water Pump: A Step-by-Step Guide

What is priming a pump? This is one of the most common questions we receive in our store and repair shop at Dade Pump & Supply.

Priming a pump refers to removing air from the system and filling the pump and suction line with water. Many pumps used for irrigation, water supply, pressure boosting, and other applications require the pump to be self-primed before the first use.

Failure to properly prime a pump can cause it to run low on water or without water at all. Running a pump dry can result in premature mechanical seal damage and may also damage internal pump components. Damage caused by improper operation or dry running may not be covered under the manufacturer's defect warranty.

When the complete system is properly installed, a check valve or foot valve should help hold water in the line after the self-priming process. It is also a good idea to regularly inspect your system—including valves, fittings, and piping—to ensure proper water flow and prevent air from entering the system.

Please follow the steps below to ensure your water pump is properly self-primed before operation.

How to Self-Prime a Water Pump

Step 1: Open the Valves

Open all valves on the suction and discharge lines. Make sure any hoses or connections on the discharge side of the system are also open and ready for normal operation.

Step 2: Remove the Priming Plug

Remove the plug on the discharge cross or tee fitting, depending on the plumbing configuration of your pump system.

Step 3: Fill the Pump and Suction Line With Water

Fill the pump and suction line with water.

DO NOT RUN THE PUMP DRY. Running a pump with low water or no water can damage the mechanical seals and may damage or melt internal components, including the diffuser and impeller.

Be sure the discharge valve is open after the pump is running to allow proper water flow through the system.

Step 4: Replace the Plug and Start the Pump

Replace the plug on the discharge fitting and start the pump.

Water should typically become visible within 10 minutes or less. The amount of time required for the pump to prime will vary depending on several factors, including the depth of the water table in the well and the length of the horizontal suction line.

If water is not visible within 10 minutes, stop the pump and restart the self-priming process beginning with Step 1.

Why Proper Pump Priming Is Important

Properly priming your pump helps establish water flow and reduces the risk of running the pump without sufficient water. A properly installed system should also help maintain prime after the initial self-priming process.

Regularly inspect your pump system for potential problems, including:

• Leaking valves or fittings
• Damaged or leaking piping
• Air entering the suction line
• Loss of water from the suction line
• Reduced or inconsistent water flow

If your pump repeatedly loses its prime, there may be an issue with the check valve, foot valve, plumbing, fittings, or another component of the system.

Important Safety Information

PLEASE NOTE: Dade Pump recommends having a licensed professional install and prime your pump.

If you are performing the installation yourself, please use caution and follow the manufacturer's installation and operating instructions for your specific pump.

If a pump runs continuously without liquid, water inside the piping and pump may become extremely hot and may boil. This can damage pipes, fittings, and pump ports and potentially discharge dangerous scalding steam or water.

Need Help With Your Pump?

Since 1960, Dade Pump & Supply, DBA De Ruiter Electric Motor Company, has been a source for pumps, parts, repairs, and technical assistance. Our team works with pumps and motors used in irrigation, water supply, pressure boosting, wastewater, sewage, and many other applications.

Whether you need help understanding your pump system, selecting replacement equipment, or repairing an existing pump, Dade Pump is here to help.