How to Prime a Well Pump
If your faucets suddenly run dry or your pump runs without building pressure, learning how to prime a well pump is often the fix that gets your water flowing again. Priming means filling the pump and suction pipe with water so the pump can create the suction needed to pull water up from your well. Without that water already in place, a jet pump will just spin air and never draw a drop. The good news is that priming a well pump is a straightforward job most homeowners can do in under an hour with basic tools, as long as you follow the right steps and stay safe around electricity and water.
What Does Priming a Well Pump Mean?
A jet pump sits above ground, usually in a basement, pump house, or well pit, and pulls water up through a suction pipe. Unlike a submersible pump that lives underwater, a jet pump cannot pump air. It needs water already inside the pump casing and suction line to create the vacuum that lifts water from the well. When that water drains out, the pump has "lost prime," and it cannot move water no matter how long it runs. Priming is simply refilling that space with water so the pump can do its job again.
Pumps lose prime for a few common reasons. A power outage can let water drain back down the well if a check valve or foot valve is weak. A leak in the suction line lets air in and water out. Running the well dry during a drought or heavy use can empty the line. And any time the system is opened for repair, such as replacing a pressure switch or pressure tank, air enters and the pump must be primed again afterward. Knowing how to prime a well pump yourself saves a service call every time one of these events happens.
Signs Your Well Pump Lost Its Prime
The most obvious sign is no water at all, or only a weak sputtering trickle, while the pump motor runs continuously. You may hear the pump running much longer than usual without shutting off, because it never reaches the cut-off pressure. The pressure gauge on the tank may read low or bounce around, and you might hear gurgling or sucking sounds from the pump. In some cases the pump cycles on and off rapidly or the motor overheats from running dry. If you notice any of these symptoms after a power outage, a repair, or a period of heavy water use, lost prime is the first thing to check before assuming the pump itself has failed.
Before you start, rule out simpler problems. Check that the breaker is on and the pressure switch is not tripped. Make sure the well has water and that no main valve is closed. If the pump is hot to the touch, let it cool and check whether its thermal overload has tripped. Once you have confirmed the pump has power and the well is not dry, priming is the logical next step.
Tools and Supplies You Need
Gather everything before you begin so you are not hunting for tools with the system open. You will need a garden hose or several gallons of clean water, a bucket, a wrench or pliers that fit the priming plug, thread seal tape or pipe thread sealant, and towels or rags for spills.
Safety matters here. Always turn off power to the pump at the breaker before removing any plug or fitting, and verify it is off. Water and electricity are a dangerous combination, so never work on a pump with wet hands while power is connected. If wiring looks damaged, or if you are unsure about the electrical side, call a professional rather than taking a risk.
How to Prime a Shallow Well Jet Pump
Shallow well jet pumps are the most common type homeowners prime themselves. These pumps sit above ground and draw water from wells less than about 25 feet deep through a single suction pipe. Start by turning off power at the breaker and opening a faucet in the house to relieve pressure in the system. Locate the priming plug on top of the pump housing; it is usually a square-headed or hex plug near the discharge outlet. Remove it with a wrench, keeping a bucket underneath to catch any spill.
Slowly pour clean water into the opening until the pump housing and suction pipe are completely full. This can take several gallons, because you are filling the entire suction line down to the well. Once the opening stays full, replace the priming plug and tighten it snugly, using fresh thread seal tape if the old tape is worn. A loose or leaking plug will let air back in and defeat the whole job.
Close the faucet you opened, restore power, and watch the pressure gauge. The pump should start building pressure within a minute or two. Open a faucet slightly to let remaining air bleed out; the water may sputter at first, which is normal. If pressure climbs to the normal cut-off range, typically 40 to 60 psi, and the pump shuts off, you have succeeded. If pressure stalls or the pump runs without building pressure, turn it off, let it cool, and repeat the priming process. Two or three attempts are sometimes needed to clear all the air from the line.
How to Prime a Deep Well Jet Pump
Deep well jet pumps work on the same principle but use two pipes, one to send water down to the ejector in the well and one to bring it back up. The priming process is similar, but there is more pipe to fill, so it takes more water and more patience. Turn off power, relieve pressure, and remove the priming plug on the pump housing. Fill slowly until water remains at the top of the opening. Some deep well systems also have a priming tee or a separate fill port on the piping; your pump manual will show the exact location.
After replacing the plug and restoring power, give the pump several minutes to build pressure. Deep well systems move water through a longer path, and air trapped in the down pipe can take a few cycles to clear. If the pump runs for more than a few minutes without building pressure, shut it off to avoid overheating, re-check the plug for leaks, and prime again. If repeated attempts fail, the problem is likely a leak in the suction piping, a faulty foot valve, or a failing ejector, and a well technician should inspect the down-well components.
What About Submersible Pumps?
Submersible pumps do not need priming in the usual sense, because they sit below the water level inside the well and are always surrounded by water. If a home with a submersible pump has no water, the cause is almost never lost prime. More likely culprits include a tripped breaker, a failed pressure switch, a bad capacitor or control box, a broken wire, or a pump that has actually failed. Pouring water into a submersible system will not help and can waste time while the real problem goes unaddressed.
That said, a submersible system can lose water flow if the well itself runs dry or the pump intake is blocked by sediment. If your submersible pump runs but delivers no water, check the pressure switch and control box first, then call a well professional to test the pump and check the water level. Knowing which type of pump you own saves you from priming a pump that never needed it. If you are unsure, look at your setup: a pump sitting on the floor in your basement is a jet pump, while a system with only a well cap outside and a pressure tank inside almost certainly uses a submersible pump. For more background on pump types, see our well pumps hub and our comparison of submersible vs jet pumps.
Troubleshooting: Pump Will Not Hold Prime
A pump that primes fine but loses prime again within hours or days has a leak somewhere in the suction side. The most common culprit is the foot valve, the one-way valve at the bottom of the suction pipe that keeps water from draining back into the well. When it wears out or gets stuck open with debris, water drains back every time the pump stops. Replacing a foot valve means pulling the suction pipe, which many homeowners leave to a professional, especially on deep wells.
Other causes include cracked or loose suction piping, a bad check valve, a leaking priming plug, or a suction line joint that has worked loose. Inspect every visible joint and fitting for drips or mineral stains while the pump is running and after it stops. Even a tiny air leak on the suction side is enough to break prime, because the pump pulls air in through the leak instead of water up from the well. Also check the well water level: during dry spells, a falling water table can drop below the foot valve, and no amount of priming will fix a well that is temporarily dry. If your pump keeps short cycling after priming, the pressure tank or pressure switch may also need attention.
Running a pump dry for long periods can overheat and damage the motor and seals, so do not let it run indefinitely while you troubleshoot. If you have primed three times without success, or if you suspect a down-well problem, shut the pump off and call a well service company. A professional can pressure-test the suction line, inspect the foot valve, and check the well level with proper equipment.
How to Prevent Losing Prime Again
Once your pump is primed and running, a few habits reduce the chance of repeating the job. Replace a suspect foot valve or check valve promptly rather than re-priming every week. Inspect suction piping and fittings annually for leaks, corrosion, and loose joints. Keep the pump house protected from freezing, since a frozen and cracked suction line will lose prime and flood when it thaws. After any plumbing repair that opens the system, re-prime immediately and check for leaks at every disturbed fitting.
Consider a few upgrades if prime loss keeps recurring. A high-quality brass or stainless foot valve lasts longer than a cheap plastic one. A properly sized pressure tank reduces pump cycling and wear on valves. And if your well water level is dropping, a well professional can advise whether lowering the pump intake or deepening the well makes sense. Choosing the right equipment from the start also helps; our best well pumps of 2026 guide and well pump HP size guide can help you match a pump to your well depth and household demand.
Priming a well pump is one of those homeowner skills that pays for itself the first time you use it. With the power off, the plug out, and clean water poured in slowly, most jet pumps are back in service within the hour. Keep an eye on the pressure gauge, be patient with trapped air, and treat repeated prime loss as a symptom worth fixing, not a routine to repeat forever. If you ever feel unsure about the electrical work or the down-well parts, a local well technician can sort it out quickly and safely.