How to Prime a Well Pump

If you own a well with a pump, there’s a very high chance that you will need to prime it. But if you’ve never primed a well pump before, you might be wondering where to begin.

Some 43 million people in the US own a private well, so if you’re struggling to get your head around well maintenance, you’re certainly not alone.

A well pump, in simple terms, is a pump that sends water from an underground well towards your home. There are several types of well pump available, including convertible jet pumps, submersible well pumps, and shallow well pumps.

150,000 readers visit my website on a monthly basis for advice and information on all aspects of water treatment, and many of these people are well owners. With my knowledge and experience in the field, I’m here to answer all your well-related questions – and priming a well pump is a good place to start.  

In this article, I’ll teach you how to prime your well pump, depending on the pump you own.

💡 What Causes a Pump to Lose Its Prime?

If no water comes out of your faucet when you switch it on, it can be a worrying sign. But before you assume that your pressure tank may have broken or you’re in near of an entirely new pump, the problem might be a lot easier to diagnose and resolve – perhaps your well pump has simply lost its prime.

One of the simplest causes of pump prime loss is a lack of water in the well. You need water to prevent air gaps and produce a good suction. If the pump isn’t fully submerged in water, you may have issues with accessing water at all.

Aside from this, however, there are a number of reasons your pump may lose its prime, including one or several of the following:

• Check value failure
• Leaking water lines
• Air gaps in the feedline
• Running tap or hose causing drawdown

It’s important to know the type of well pump you own before you consider how to deal with it.

There are some giveaways if you’re not sure – you just need to know whether you own a shallow or a deep well.

For instance, a jet pump can be used for shallow wells, while convertible jet well pumps are likely to be used in a deep well system. Priming is only needed for jet suction pumps, not submersible pumps, which are constantly in water already.

✔️ How to Prime a Shallow Well Pump

To prime a shallow well pump, follow the below instructions:

1. Start by switching the pump off, then unplug it from your power supply.
2. Check that neither the pump or the connectors are displaying signs of damage, such as cracks.
3. Find the prime plug (which is typically on the head of the pump). Remove this plug and set it aside.
4. If you can open any pressure relief valves, do so now. This will prevent a buildup of water pressure inside the system.
5. Next, locate your garden hose (make sure this is lead-free). Run water through the hose to clean it out. Note that you can use a bucket or large bottle for priming the pump, but a hose is the easiest solution.
6. Once your hose is ready, use it to fill the casing of the pump until water flows from the valve and prime plug. You can now replace the prime plug. Make sure the water you use is clean and potable if you use your well as a drinking water supply.
7. Finally, connect the pump and set the system to run through a normal cycle. Watch the pump – if it is working correctly, your job is done. Close the pressure relief valves, precharge the pressure tank, and use your well water as normal.
8. You may need to repeat the process once more. If your check valve or foot valve aren’t working properly, water may end up back in the cistern after the pump has turned off. This can create an air pocket in the pipe, which will prevent the pump’s ability to suck water up. If you notice this issue, shut off the system before the motor burns out and prime your water pump again.

✔️ How to Prime a Deep Well Pump

Priming a deep well pump follows virtually the same process. Here’s what you need to do:

1. Switch off the water pump and unplug it from its power source. Release any water pressure by opening a faucet or any pressure relief valves. Next, remove the plastic or rubber prime plug and insert a hose into the hole on top of the pump.
2. Fill the pump casing with water until it is so full that water starts to leak out of the casing.
3. Take the hose out of the hole and replace it with the prime plug. Don’t insert the plug fully – allow for gaps around the hole. Switch on the pump system and run until you can see no more air bubbles coming from the bottom section of the plug.
4. Take the priming plug out of the hole and repeat the process once more, filling the water pump casing until it begins to leak. Plug the hole as you did before, then switch on the system and wait until there are no more air bubbles. Repeat until only water leads from the pump. You should no longer be able to see air bubbles.
5. Replace the prime plug and precharge the pressure tank Your deep well pump system is now ready to use once more.

Priming a Convertible Jet Pump

There are usually two pipes that make up a convertible jet pump: a pipe for sucking up well water, and a pipe that sends water into something called a venturi loop, towards your outlet valve. Convertible jet pumps are powerful enough to be used as an option for deep well systems.

To prime a convertible jet pump, follow the same instructions as above. Just remember, a convertible jet pump has two pipes, and both will need to be fully submerged underwater when you’re priming to prevent trapped air in the system.

❔ Frequently Asked Questions

Do you have to prime a well pump?

Yes, priming a well pump is essential. Your pump simply won’t be able to function properly without being primed. When you prime the pump, it manually produces a pressure vacuum that allows well water to be sucked up from the well and send into your piping and plumbing. Pump priming can prevent leaks in your well system, as well as preventing backflow.

You will have to prime your well pump as soon as you install your well. Depending on the quality of the pump and your own circumstances, you may also need to re-prime the pump if it experiences any malfunctions.

If you don’t want to prime your pump, consider self-priming pumps. These are a particularly good option for a deep well, as they’re designed to work effectively in deep water. The turbulent turbine action from a self-priming pump helps to keep the area full of water, preventing air pockets from becoming trapped in the pump piping or casing.

How much water is needed to prime a well pump?

Your water requirements depend on the type of pump you’re dealing with and the number of times you need to repeat the process. There’s no definite answer – the makeup of your pump system and the problem you’re dealing with (and whether you’re even dealing with a problem at all!) will determine the water needed. Most well pumps will need several buckets worth of water. Remember, if you’re using your well for drinking water, you should only prime it with drinking water.

How long does it take to prime a well pump?

Again, this depends on the problem your system is facing and how many times you need to repeat the process. The majority of shallow and deep well pumps will only take a matter of minutes to prime. It should take less than half an hour to fill the casing with water, test the pump and get it up and running again. For older water pumps or those that have suffered damage, you may want to consider replacing your components to make the task a little easier.

Are well pumps self priming?

You might not even need to prime the pump of your well at all if it’s self-priming. Not all pumps are self-priming, however, so it’s important to be certain on this matter if you’re looking specifically for a pump that can prime itself.

Typically, submersible well pumps are self-priming. These pumps, as the name suggests, are installed underwater. The pumping unit connects up to a source of power, and, because it’s underwater, it doesn’t need to be primed. However, you’ll usually still need to add water to the pump casing when you install the pump to enable the priming process to begin. Providing you have a foot valve or check valve installed, preventing the well from losing suction, it shouldn’t need to be re-primed going forward. Of course, if either valve fails, your pump won’t work, either.

Non-submersible pumps, on the other hand, will usually require manual priming. These pumps are better for installing in shallow wells, and the instructions in this guide are applicable for most non-submersible pump priming jobs.

Why is my well pump not priming?

There are a number of reasons why your well pump won’t prime. If you’re having an issue with the pump itself, check that none of the components have broken. The check and foot valves can become worn and require replacing eventually. You may also have loose fasteners, leaky piping, or fittings that need tightening.

Another potential issue is if your pump is losing pressure. Installing a pressure gauge on the outside of your well will allow you to monitor the water pressure of the pump and piping. In the case of a pressure dip, check for clogs in your water pipes. Should you have no noticeable issues, it’s worth considering installing a booster pump, which should allow you to re-prime your pump and bring it back to proper functioning.

What can I do if I’m still uncertain?

Priming a well pump can seem like a daunting prospect. The process itself is actually relatively straightforward, but doing it the first time may be challenging. You might wonder whether you’re priming your pump right, and whether you’re achieving the desired outcome.

You will know whether priming the pump has worked or not because it will affect the water supply to your home. If you would prefer support, however, you could call a plumber and ask them to guide you through the job (this will come at a cost). A plumber can reassure you that you’re following the proper steps for priming your specific well pump. You can also make note of the things they tell you in case you need to prime the pump in the future.