How To Prime a Pool Pump

Written by:  Danny Rhodehamel

When a system is fully primed, the system components, pipes, pump, filter etc., are filled with water and the pool pump is able to suck water from the pool and push it back into the pool through pool returns. Priming a pool pump involves purging air from the pumping system and filling the water lines and pump with water. The number of steps required to prime your pool pump depends on the amount on water in the suction side of the lines - water coming from the pool to the pump. If you are installing a new pool system, there is no water in the lines, and you may have to repeat these steps several times. If you are adding or replacing components into the pumping system (like a heater), there will still be some water in the lines and priming will be simpler. The following procedure assumes that you have no or little water in the system. Visible indications of low water are no or little water in the pump strainer box, and a low pressure reading on the pool filter pressure gage.

Tips & Warnings


Things You'll Need

Step by Step

Step 1

If the pool pump is running, your first step is to turn off the power to the pool pump. For maximum safety turn off the power at the circuit breaker to the motor.

Step 2

The suction diverter valve allows you to shut off water from the skimmers or from the main drain. Generally you cannot shut off both. To prime the system in steps, move the diverter valve so that the off side of the lever is pointing to the main drain side. Now water can only flow from the pool skimmer lines. Note: if you are only adding a component to an existing system, water will still be in the lines and you can probably re-prime the system by opening the skimmer and main drain lines at the same time (lever is halfway between skimmers and main drains).

Step 3

Next you will have to relieve any pressure that remains in the pool pump and water lines. To relieve pressure turn the air relief valve on top of the pool filter counter clockwise. You will hear air releasing as you see the pressure on the pressure gauge go to 0 psi. Leave this relief valve open.

Step 4

Open the lid to the pool pump strainer box. To open up the strainer box, 1-turn the two knobs on top of the strainer lid counter-clockwise and 2- swivel the knobs down away from the lid. Note: Some strainer lids screw on instead of having knobs. In these cases twist the lid counter-clockwise to remove the lid off the top of the strainer box.

Step 5

Remove the pool pump strainer basket and clean out any debris that has accumulated. Replace basket.

Step 6

Fill the pool pump strainer box with water using a garden hose or bucket.

Step 7

Replace the strainer lid carefully to ensure a good seal. Hand tighten only. If your pool pump has knobs, tighten them evenly by hand. Do not use tools to tighten the lid.

Step 8

Ensure that the diverter valve to the pool return is open. This will allow the pool pump to discharge water to the pool. If this is not open, excessive water pressure that builds up during pump operation may damage parts of the pumping system and may be dangerous.

Step 9

Restore power to the swimming pool pump.

Step 10

Check the water flow through the strainer box. Water should flow freely in 30-60 seconds.

Step 11

The air relief valve should still be open. As the pressure builds, air will be released through the relief valve. When water starts to spray out of the valve, turn the valve clockwise to close it.

Step 12

If water isn't flowing freely in 30-60 seconds, repeat steps 1 - 10: turn off the pump, bleed off the pressure, reopen the strainer, refill the strainer, and close the lid. Then turn on the pump. You may have to repeat these steps several times to purge the air from the line.

Step 13

When water is flowing through the pool skimmer lines, slowly open the main drain line at the diverter valve. Open the relief valve to allow air in the main drain line to escape. Again water should flow freely in 30-60 seconds. Close the relief valve. If you don't see pressure building on the pressure gauge and a full strainer box, repeat steps 1 -10.

Step 14

After the system is fully primed, move the diverter valve halfway between skimmer and main drain for normal operation.

Step 15

If, after repeated attempts, you cannot prime the system successfully, your system has a major leak or blockage. This problem must be resolved before you can prime the swimming pool system.

Comments (1 to 40 of 93)

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User: Inyopools

Scott72 - Concentrate first on what you changed. If you pulled the strainer cover off to clean the basket, make sure the cover O-ring is in place. Sometimes, if the O-ring is old and stretched out, it may poke out when you are closing the cover leaving a big air hole. If that is good, try filling the pump trap with water from a hose. You won't be able to fill it but you will put some water in the pipe to the pool. Leave the multiport valve in filter until the system is primed. Turn the pump off and switch to backwash, then switch the power back on.

User: Scott72

I've got an older pool with a Heyward S200 sand filter. I don't have a diverter valve from the main line to the skimmers; just the pump selector lever (backwash, rinse, filter, etc.). According to the instructions on the pump, I am supposed to prime it, then run it on backwash until I had a steady flow of water, then rinse, then filter. I had this thing running great yesterday, opened the basket to empty it, and now can't get it to prime to save my life. Am I missing something? Please help! Thank you!

User: Inyopools

check valve - The check valve should keep the water from flowing back into the pool after the pump is shut off. So priming would be faster.


How would this work if there is a check valve on the suction side of the pump?


Worked great. Thanks.

User: Inyopools

prime - Generally you will see a little water/air at the top of the pump basket while the pump is running. I have seen a perfectly smooth top where it looks like no water is flowing but this is an exception. The discharge from the pump would have to match the water coming in on the suction side of the pump. If you have a lot of air in the pump basket (Cavitation) you either have a suction air leak or your pump may be too large and it is discharging the water faster than it can pull it in.


should you see water in your pool pump when its running

User: Inyopools

creepy backwash - Sound like you don't have sufficient water flow in the filter setting. If you haven't replaced the sand in your filter in the last 5 years, I would do that first. See our guide on "How To Correct Low Water Pressure in Your Pool System" for other suggestions.


My creepy only sucks of backwash. How do I correct this please

User: Inyopools

Bigredthingy - Try placing Tupperware covers over the input and return holes on the inside of the pool. The pool water pressure should hold them against the holes.

User: Bigredthingy

We already have our pool full and a pump and cartridge filter hooked up, but old cartridge leaks in too many places! I have a new pump and cartridge filter system that we want to hook up and don't know how to stop all the water from pouring out on us while we exchange the equipment! Please, help!

User: Inyopools

have know clue - Hard to say. Go back and look at everything you might have changed to make sure it is the same as it was - assuming your system was running well before you painted. Check the voltage connections and readings to make sure your voltage is correct. This problem is characteristic of low voltage to the pump.

User: have know clue

my pool was drained five month . was repainted and filled up, primed the pump, and flipped the switch pump came on for twentyfive sec,then me somebody

User: Inyopools

Tavo - If you tried opening the main drain after you had the system running with the skimmers, and you lost prime, it sounds like you have a leak in the pipe coming from the main drain to the pump. Try soaping up any visible connections between the diverter valve and the main drain to see if any bubbles are sucked into a leak. If not, your leak may be underground.

User: Tavo

I have not been able to prime my pump using the main drain. I let the water run inside the pump basket for at least 20 min but if never filled up. I gave up on the main drain and the pump it's running once I changed to skimmers only. I have try opening the slowly to the main drain but have not have success. My concern is that I ran the water to the main drain for a long time and no luck.

User: Inyopools

Golden-Hawk - We only sell the rubber flapper as a kit with this valve.

User: Inyopools

Golden-Hawk - No, it will not hurt the pump to prime for 5 minutes.

User: Golden-Hawk

I am using 2" Jandy Check valves to prevent back flow< Is it possible to buy just the rubber flapper instead of the $30.00 kit?

User: Golden-Hawk

Hello, I have a 30k pool with dual mains and dual skimmers. The pump is app. 6' above the water line.Both Mains and skimmers have Jandy ck valves to slow run back. The pump is on a auto timer and after several hours of off time, its takes about 5 min to prime the pump. Is this going to damage the pump? Thx,Ken

User: Inyopools

HH - Most pool systems will drain back into the pool when the pump is shut off. If your pump is higher than normal above the pool surface it will drain more. One way to stop this backflow is to put a check valve in your system after the pump.

User: HH

my filter set up always loses the water when shut off, i have to reprime every day.
I can hear buble noise inside the filter, that means some air is entering it and some water goes to the pool.

I suspect there's a leak that the air gets in - but i see no leak at all when the system is running?


User: Inyopools

Larry - We generally recommend a pump size of 1 HP for your pool size and configuration. I would not install a pump less than 3/4 HP.


Larry I am replacing my old 3/4 hp pool pump to a pentair whisperflow ee 1/2 hp can the new pentair handle my 20,000 gal pool and pump water to my solar panels on my 2 story house?

User: Stephen

It worked. I really appreciate the help. I know where I will be purchasing all my pool needs now.

User: Inyopools

Stephen - I talked to the Hayward rep and he suggests changing the prime setting in your Ecostar pump from "auto prime" to "3 minutes". Please let me know if this works. Thanks

User: Stephen

I have a Hayward Ecostar pump and a Hayward filter. For some reason the pump will not prime in filter mode. It will prime in backwash, rinse, recirculate...just not in filter. Any suggestions?

User: Inyopool

Ed - Depending on the height of you pump relative to your pool level, you may have drained most of the water from your suction pipes. Fill the strainer basket with your hose for 5 minutes. Secure the strainer cover and try running your pump again. It might take 5 minutes to prime fully.

User: Ed

I just drained and cleaned out my De filter. Does it take longer to prime the pump after that? I've tried several times but can't get water to flow.

User: Inyopools

Kelly B - Sounds like you may have shorted out the motor. See "How To Use a Multimeter to Test a Pool Pump Motor - Winding Resistance" to test the windings or take the motor into a pool shop to be tested.

User: Kelly B

My top filter housing cracked causing the water to possibly spray on my motor and lose a lot of water from my system. My motor was trying to start because of the timer without having enough water in the basket attached to the motor. Now I try to prime the pump but the motor turns over for a couple seconds and then turns off. It will continue trying to start if I don't turn the pump off. I tried stuffing a hose and rag in the skimmer basket at the pool to fill the line enough for the pump, with this I had to divert from the main drain to the skimmer a little for the water to fill the pump line enough to get the water to over flow the priming basket to try to get the pump to stay on. I need advise on what to try next. Do I need to make sure the pressure from the filter is zero before trying this again? The impeller spins and seems free of debris. The pump wants to start but something is making the motor shut off for a few minutes until it tries to start again and again. Thanks!

User: Inyopools

Kelly - Consistent bubbles in the return jets is an indication that you have a suction leak somewhere ahead of the pump. I would look at any new connections you made in installing your new pump. As long as you have good flow you should be all right now. If your pressure gauge is showing 0, you either have a bad gauge or your flow isn't as good as you think it is - probably due to the suction leak. See our guide on "How to Identify and Correct Air Leaks" for more information.

User: Kelly

We have an in ground pool and just purchased a new pump and filter this year. We hooked everything up and were reading around 9 psi with great suction and return. We vacuumed, then cleaned pump basket, backwashed and rinsed then returned to filter and have 0 psi now. Weird thing is we still have suction and good pressure of water returning to the pool. But there is a lot of air bubbles coming from our jets. I'm at a lost. Our main drain is closed...we never have used it. I don't want to ruin our new pump or filter. Please help!!! Thanks

User: Inyopools

Frank - Here's a link to some common pool system configurations: Plumbing Schematics.

User: Frank

you keep mentoning the different valves like the diverter valve and the position it should be. but I dont know which is which. Please can you give me a diagram so I know which one is which valve and their positions.

User: Inyopools

TR - Three thoughts. 1- It is not uncommon to have an initial pool pressure of 6 psi on a new system. However, if you have the same filter, I would have expected that the psi would be closer to what it was before you changed the pump. 2- You may have had some resistance in the heater lines that was removed. 3- You may have a smaller “1 HP” pump. Real or Total HP (THP) is the product of HP and SF. Check the labels on your motors. If your old motor had a HP of 1.0 and a SF of 1.65, its THP was 1.65 HP. If your new motor has a HP of 1.0 and a SF of 1.0, its THP is 1.0.

User: TR

Just repaced my old Pool Pump yesterday with a brand new 1 HP pentair pump...Pool heater had gone so the pool tech looped the in/out lines together so that we could remove heater until replaced..Pump started and it seems to be working fine except that the pressure is around 6 PSI..Pool guy says that a new pump with a clean filter should read between 5-10 PSI...I always thought that it should be around 12-16 PSI...I notice a few bubbles in the return line...OLd pump didnt have this...Any ideas?

User: Inyopools

TTFNWEN - If your pump is maintaining prime and your filter gauge is showing little or no pressure, I suspect that your pump is undersized. As a gross benchmark, we usually recommend a pump of 1 to 1 1/2 HP for a typical in ground pool. I have noticed on a two speed pump, when you use the low speed and reduce the HP by half, the pressure gauge can show 0 or very low psi. Your pump might be undersized by 2/3 to 1/2 the needed HP. Have a pool professional do a pool system analysis for you.


I have an inground pool. My pump is NOT drawing water from the skimmer. I have checked the impeller and it is clean and turns. However, I have noticed the glass backwash indicator is not filled with water. I suspect my filter is not full of water and my pressure gauge does not work. Can this be the cause? I have used a shop-vac to test the lines and it draws water, so I don't there's a blockage on the suction side. Also, only one of the returns is working and not very strong.

User: Inyopools

doityursel - If your pool was very dirty when you opened it up, you may have clogged your filter especially if your added chemical to help clear it up. When possible, that water should bypass the filter and go out a waste line. Try backwashing or cleaning your filter a number of times as you are filtering to the point that your water is clear. Also check your pumps impeller to see if it was clogged. See "How To Clean Out a Pool Pump Impeller"

User: doityurself

After opening for the summer, the pump started fine and ran very well for at least thirty minutes. My son vacuumed for another thirty minutes (into the skimmer basket), and started to lose prime. I don't think he pulled the vacuum head out of the water or it would have died immediately. Water flow got weaker and weaker. Finally lost prime altogether. Now I can't get it to prime again. Starts for a minute then the flow turns to a trickle and dies. Thinking I have an air leak or a bad seal? Any other obvious possibility I'm missing? I don't see how I could have a blockage. Help would be greatly appreciated.

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Tips & Warnings

Never run a pool pump without water. Running the pool pump dry for any length of time can cause severe damage to both the pool pump and the motor.

Please Note:

Inyo Pool Products is not responsible for any injury or damaged equipment
while using our guides. Using our guides is doing so at your own risk.
These guides are suggested use of your pool or spa equipment and may vary
depending on which product you are using.