Learning how to prime a water well jet pump is one of those skills you hope you never need, but when you do, it's a total lifesaver. You usually realize something is wrong when you turn on the kitchen faucet to wash some dishes and all you get is a pathetic hiss of air or a weak trickle that eventually gives up. It's frustrating, especially if you're in the middle of a busy morning, but don't worry—it's usually not a sign that your pump is dead. Most of the time, it just means air has worked its way into the system, and you need to get the water moving again.
Why did my pump lose its prime?
Before we jump into the "how-to" part, it's worth asking why this happened in the first place. Jet pumps aren't like the submersible ones that sit deep inside the well. They stay above ground and rely on suction to pull water up. Because they use suction, they need a solid "column" of water to work. If air gets into that column, the pump just spins its wheels (or its impellers, rather) without moving any water. It's like trying to drink through a straw that has a hole in it.
This usually happens after a power outage, if the water level in the well dropped too low, or if there's a tiny leak in the piping. Sometimes, a "foot valve" at the bottom of the well gets stuck or worn out, letting water drain back down into the well and leaving the pump high and dry. Whatever the reason, you've got to get that air out and the water back in.
Getting your gear together
You don't need a massive toolbox for this, but you will need a few basics. Grab a large wrench (usually a pipe wrench or a large adjustable one) to loosen the priming plug. You'll also need a bucket or two of clean water. This part is a bit ironic—you need water to get water—so hopefully, you have some stored or a neighbor can lend you a gallon. A funnel is also a huge help unless you have incredibly steady hands, as the opening you'll be pouring water into is usually pretty small.
Safety is the first step
Seriously, turn off the power. You're going to be messing around with water and an electric motor. Go to your breaker box and flip the switch for the well pump. You don't want the pump trying to kick on while you have the plug off or while your fingers are anywhere near the moving parts. Plus, running a jet pump "dry" (without water) for too long can actually melt the internal seals, and then you'll be buying a whole new pump instead of just priming this one.
Finding the priming plug
Once the power is off, head over to the pump. You're looking for a small square or hex-headed bolt on the top of the pump housing. This is the priming plug. On most models, it's located near the highest point of the pump body. If you're lucky, it hasn't been touched in years and might be a little stubborn, so give it a good tug with your wrench.
Be careful not to strip the threads or crack the housing. If it's stuck, a little bit of penetrating oil can help, but usually, a firm, steady pull does the trick. Once you get it loose, unscrew it the rest of the way by hand and set it somewhere safe—don't lose it in the dirt!
Filling the pump with water
Now comes the part where you actually "prime" the thing. Stick your funnel into the hole where the plug was. Slowly start pouring your clean water into the pump. You might hear some gurgling and bubbling—that's a good sign! It means the air is escaping and the water is taking its place.
Watch for the "burp"
If you have a shallow well (one pipe going into the ground), this might go pretty fast. If you have a deep well jet pump (two pipes), it might take a lot more water than you expect because you're filling up those pipes as well as the pump itself. Keep pouring until the water stays level at the very top of the hole. Wait a minute or two to see if the level drops. If it does, it means the water is trickling down into the pipes, which is fine—just add more until it stays full.
Closing it back up
Once the water is sitting steady at the top of the opening, it's time to put the plug back in. I like to wrap a little bit of thread seal tape (Teflon tape) around the plug threads before I put it back. This ensures a vacuum-tight seal, which is exactly what you want. Screw it in by hand first to make sure you aren't cross-threading it, then snug it down with the wrench. You don't need to crank it with all your might—just make sure it's tight enough that air can't leak in.
The moment of truth: Restarting the pump
Now, go back to the breaker and flip the power on. You should hear the pump motor kick in. Keep an eye on the pressure gauge on the side of the pump. If everything went right, the needle should start climbing. It might take a minute or so for the pressure to build up fully.
If the pump runs for a minute and the pressure isn't moving, or if you hear a lot of angry vibrating, the prime didn't "catch." Don't let it run like that. Turn the power off and repeat the process. Sometimes it takes two or even three tries to get every last bit of air out of the line, especially if the well is deep.
What if it still won't prime?
If you've tried three times and you're still getting nothing but air, there might be a deeper issue. Here are a few things to check:
- Check the Foot Valve: This is a one-way valve at the bottom of the well pipe. If it's broken, the water will just keep draining back into the well as fast as you can pour it in.
- Look for Suction Leaks: Even a pinhole leak in the pipe leading from the well to the pump can suck in enough air to break the prime. Look for any wet spots on the pipes or listen for a faint "hissing" sound.
- Water Level: If your well has run dry or the water level is extremely low, the pump simply won't have anything to grab.
Finishing touches
Once the pump reaches its "cut-off" pressure (usually 40 or 50 psi) and shuts itself off, go inside and turn on a faucet. You'll probably get a few big "shudders" and some air spitting out of the tap. This is normal. Let the water run for a few minutes until it's clear and the flow is steady.
Knowing how to prime a water well jet pump is a great way to save yourself a couple of hundred bucks on a plumber's house call. It's a bit of a messy, wet job, but once you hear that pump hum and see the water flowing again, it's incredibly satisfying. Just remember to take your time, keep things clean, and always, always turn off the power first!