How to Correct Low Water Pressure in Your Pool System


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Low pressure is a pool term that is often used to describe weak jets as well as a low PSI reading on the filter’s pressure gauge. High PSI readings will also cause low water pressure. A low or high PSI reading is anything outside the normal operating pressure of the filter. Weak jets, air bubbles, slow pool cleaners and weak water features are obvious signs of low pressure. This guide addresses the common causes of low water pressure in a pool.

Things You'll Need


Step by Step


Step 1

Your pool’s plumbing system can be broken into two sections: the Suction-Side and the Pressure-Side. The Suction-Side of your pool includes the skimmer, main drains, plumbing, and any other equipment like diverter valves, up to the strainer housing of your pool pump. The Suction-Side is the portion of the system, your pump is pulling the water toward it. The Pressure-Side of your pump begins at your pump’s impeller; this is when the pump’s pulling becomes a pushing force to move the water through your pool filter, heater, chlorinator, and all the associated plumbing until it returns to the pool via the return jets.

Step 2

Low Water Level (Low PSI) - The water level should be at least halfway up the skimmer door's opening. A low pool skimmer water level will allow the skimmer to gulp air as your water ebbs and flows caused by the pump running or activity in the pool.

Step 3

Clogged Skimmer Basket (Low PSI) - If your skimmer basket is full of debris, you are effectively shutting off the pipe between the skimmer and the pump. Generally, this will reduce the flow of water to the pump. If the pump has less water entering it, it is moving less water out. This means the pump is doing less work that in turn will reduce water pressure.

Solution: Clean your skimmer basket by removing any debris.

Click Here to View Replacement Skimmer Parts

Step 4

Clogged Strainer Basket (Low PSI) - It is the same story as above. A clogged strainer basket means less water flow that leads to less water pressure out the returns.   

Solution: Clean your strainer basket by removing any debris.

Click Here to View Replacement Pump Parts

Step 5

Clogged Filter (High PSI) - Again, if water can't get through a clogged filter, you will have less water flowing out of the filter. Incidentally, this will increase the water pressure in the filter signaling that it is time to clean the filter.  

Solution: Wash your cartridge filter. Periodically soak the filter overnight in a TSP solution to get the grease and gunk out of the folds. Grease is produced by suntan lotion, sebum (oils secreted by the human body) and pine tree needles. Then soak the cartridge in a weak solution of muriatic acid (10:1) to get the minerals out of the folds. Use the TSP before the acid or the gunk will set up in the folds. For sand filters you will need to backwash as required. Change the sand every five to seven years. In between changes, if sand has caked on top, take one to two inches off at the top and replace it with new sand.

Click Here to View our Liquid Filter Cleaner

Click Here to View Replacement Filter Cartridges

Step 6

Clogged Impeller (Low PSI) - This problem is often overlooked. If the impeller becomes clogged with debris, water can't rotate out the sides of the impeller. This decreases suction which reduces water flow through the pump.  

Solution: Clean out the impeller. See our guide on "How To Clean Out a Pool Pump Impeller".

Click Here to View Replacement Pump Parts

Step 7

Suction Leak At Pump (Low PSI) - The pump lid o-ring, pump intake fitting, and drain plugs are common areas to draw in air. A suction leak in the suction side of the pump can cause a number of problems. If it's large enough, too much air will be sucked into the system, and the pump will lose prime. If it's smaller, air will be sucked in through the pump and start to collect at the top of the filter tank. After some time (sometimes a few hours) air pressure at the top of the tank will create enough back pressure to reduce the flow of water significantly. When the pump is shut off, this back pressure will cause the water in the suction pipe to surge back and sometimes create a column of water up though the skimmer.  

Solution: Find the suction leak and close it. See our guide on "How to Identify and Correct Air Leaks".

Click Here to View Replacement Pump Parts

Step 8

Suction Leak at Diverter Valve (Low PSI) - The diverter valves in front of the pump control the flow of water from the skimmer, main drain, and vac lines. They also have seals in them that can go bad and allow air to enter the system. Again, air will cause the water pressure to drop and will lead to the pump losing prime.

Click Here to View Diverter Valve Parts

Step 9

Suction Leak At Plumbing Fittings (Low PSI) - Any fitting on the suction side of the system can draw air. Cut out and replace any fittings that have an air leak.

Step 10

Clogged Pipe Going To The Pump (Low PSI) - A clogged pipe from the skimmer, suction line or main drain reduces the amount of water to the pump which can reduce water flow to the pump and create low water pressure out the return lines.  

Solution: Push a stiff wire down the skimmer or suction ports to see if you have a clog near the entrance. If there are no clogs there, you may have to get a pool professional to come in to check your pool pipes.

Step 11

Too Many Features Opened - The pump is only designed to move so many GPM. Too many water features are like too many hoses on a sprinkler system. The first one has great pressure. Subsequent hoses will reduce the water pressure.

Solution: Alternate which features are turned on or replace the motor in your pump with a larger one. Make sure your existing filter will support the larger pump. You may also have to replace it.

Step 12

Pump Is Too Small - If your pump's size was calculated for you initial pool system and you have added more equipment onto that system, you may have exceeded the pump's capability to supply the GPM that is now required. Also, if you have moved your pump significantly further away from the pool, which required more pipe, you may have increased water resistance in the pipes that exceeds the pump's capability.   

Solution: Replace the motor in your pump. Note you may also have to increase the size of your filter if it won't handle the increased GPM water flow. See our guide on "How To Replace the Motor on Your Pool Pump".

Click Here to View Replacement Pool Pump Motors

Step 13

Bad Pressure Gauge - Pressure gauges on top of the filter do go bad. Your apparent low-pressure reading may be due to a faulty gauge.

Solution: Replace the pressure gauge. See our guide on "How To Replace a Pool Filter Pressure Gauge on a Cartridge Filter".

Click Here to View Replacement Filter Parts


(281 to 320 of 373)

 Posted: 4/7/2016 

Thank you so much!!!! Mine was a clogged impeller!!! Saved the day and a fun filled weekend!

 Posted: 3/12/2016 

Thank you very much, very informative, and pool is now running properly

 Posted: 2/15/2016 

Thanks! I had thought about trying with no filters myself, but the very firs thing I did was clean them and they are only 3 months old, so I couldn't think how a fairly new, recently cleaned set of filters could impede flow so much. Anyway, given your encouragement, I tried and and sure enough, the system was working OK. I had an old set of (dirty) filters on standby, and fitted those instead, and even they are OK, so somehow the "new" set of filters have become completely plugged up so that, even with a cleaning, there is virtually no flow. I've ordered a new set from a different brand to finish the job. Thanks for your help.

InyoPools Product Specialist  Posted: 2/9/2016 

BigBisto - You may have a clogged filter even if it looks clean. If you have a sand or DE filter, turn the multiport valve to recirculate to bypass the filter. If you pressure improves significantly, it's time to change the sand/DE. If you have a cartridge filter, pull out the filter and run without it. If that improves flow, your filter is probably clogged with oils of chemicals and needs to be replaced. Check your impeller again. A clogged impeller is a very common flow problem.

 Posted: 2/7/2016 

My system has been in place for 15 years and is as installed (i.e. no changes or additions) other than a motor rebuild and in-floor cleaning valve rebuild from time-to-time. I've been through the whole troubleshooting procedure for low pump pressure as well as checked for [obvious at least] suction leaks. To be fair, it does not look like there is air being drawn in and there is no air building up in the filter. I ran a 25' drain cleaner from the skimmer back as far as it would go and then the other way from the pump end, overlapping by at least ~6-7' by my estimate without encountering any blockages. I cannot for the life of me figure out why there is no pressure. I replaced the impeller last year and it looks to be in good shape now. Any thoughts for further troubleshooting steps? Thanks in advance for your help.

InyoPools Product Specialist  Posted: 12/13/2015 

kris - I'm assuming you installed a Pentair TA-60D Tagelus sand filter since it is the Tagelus model closest to 350 lbs of sand. First off, you may have too much sand in the filter. Our specs show filling it with 325# of sand. If you don't leave enough open space at the top of the tank, you may not be able to backwash your sand effectively. Other possible issues: under sized filter - TA-60D has a max GPM of 60. Your pump may be too large for your filter; clogged breather tube running from top to bottom of tank; return flow restricted by shutting down too many return valves.

 Posted: 12/11/2015 

I installed tagelus 350 lbs replacement filter, after backwash pressure is 23, when spa is on 33, no block on lines, what else to check?

InyoPools Product Specialist  Posted: 9/10/2015 

Chad - You may have too much DE powder in your filter. Depends on how thoroughly your cleaned it. When you clean the filter without pulling out every grid to wash it, about 20 % of the DE powder stays on the grids. If you add more than about 80% of the powder needed for your initial install, it may clog the system reducing flow and pushing some of the excess into the pool.

 Posted: 9/1/2015 

I just opened up my DE filter and cleaned it last week. After cleaning the filter I added about 3 gallons of liquid chlorine. The next day the pool seemed to be working properly and it was beginning to look much cleaner. A few more days go by and I notice my pool was starting to turn green again and seemed to me that all the dirt from the automatic vacuum was being put right back into the pool. I opened up the filter to make sure everything was put back together properly. The grids were a bit green so I cleaned them again. This time I remembered to add the DE filter powder. When adding the DE Filter Powder into the skimmer it seems like it all went directly back into the pool. Now I have a bunch of DE filter powder in the bottom of my green pool. The grids do not have any rips or tears. The pressure gauge when the valve is on pool suction dips to about 8-10. When the valve is straight up the gauge reads about 20 where it says "Start" on the gauge. What do you think is causing this issue. Are my valves not in the correct position. I apologize for my lack of knowledge in this subject but really could use some advise, other than the wife's advise which is "Hire A Pool Man"

Anonymous  Posted: 8/24/2015 

louie - I would still guess that your problem is in your cleaner suction line. Something like a toy might be stuck in the first or second elbow/tee that doesn't come out with back pressure. One customer had this problem. Try running a snake back from the pump to the suction port to see if it comes through.

 Posted: 8/23/2015 

I have very low suction. The pool sweep won't work, and the bottom drain of the 10' deep pool doesn't draw, although there is flow into the skimmer.
I have tried backflushing water from the pump inlet back to the pool sweep connection. No debris showing. the skimmer and pump baskets are pretty clear. New sand in the sand filter, followed by freshly cleaned individual grids (using water only) in the DE filter. I separated the motor from the pump casing and checked the impeller. All clear. BTW, 1HP high efficiency pump 6 years old, 35k gallon pool. No air getting into the basket. About 16psi at the sand filter, 14psi at the DE filter. This system was running just fine until about 6 months ago, when I noticed the pool sweep was running slower gradually. Now there is not enough suction to make it work at all, although you can feel some suction. Clearly not enough.What am I missing here?


InyoPools Product Specialist  Posted: 8/22/2015 

poolster - You may have a partial blockage in a major junction of your suction pipes that stops water flow over time. Maybe a toy shifting in the pipe. Does this drop in pressure occur over time? Try blowing the suction pipes backward from the pump with a wet vac. This is a long shot but I have no other explanation.

 Posted: 8/21/2015 

Thanks for the feedback! The pump impeller is not clogged and I do not see any air in the system!

On Monday The pool pressure and flow dropped again. I went to my pool equipment pad and the filter pressure gauge was at 8psi and the GPM flow meter was at 35GPM. The pump was fully primed, but making a straining sound. I simply turned the pump off, waited a few seconds and turned it back on. The pump instantly ran smooth, the filter pressure was back up at 16psi and the flow back up to 62 GPM.

I really don't know what's going on? I made a video showing what I described above. It can be viewed here: . Any ideas as to what's happening is appreciated. Thanks!


InyoPools Product Specialist  Posted: 8/18/2015 

poolster - Check your impeller for a partial blockage. It doesn't take much and this is a common problem for low pressure. See our guide on "How To Clean Out a Pool Pump Impeller" for more information.

 Posted: 8/17/2015 

I have a real doozy I can't figure out.
-Hayward Cartridge filter (525 sq.ft)3 years old. Cartridges cleaned monthly and appears to be in good shape.
-Pentair Whisperflow pump (1HP). Brand New
-Separate bottom drain and skimmer line valves with a T going into pump.
-Brand new pressure gauge
-Brand new GPM flow meter on return
-Delzone ozone system (New)
-Jandy pool heater (New)
-4 return jets in pool.

Everything functions well. Pump is fully primed. I get great flow and movement in the pool. The pressure gauge on the filter reads 17 psi. The GPM meter bobs between 67 and 70 GPM.

Then several days later I get a Psi reading of 6 and a GPM reading of 23. The pump is full of water and basket is rather clean when running. The skimmer basket is clean too. I open the air bleeder valve on the filter tank thinking there is an air pocket, but water just squirts out rather weak (no air).

I stop the pump, clean what's little inside the basket. Close the lid and start the system up again. The pressure resumes to normal (17psi) GPM returns to normal (67 - 70 GPM) and the flow in the pool is strong.

What is causing the drop in pressure? There appears to be no blockages and no air in the system. What can I do? Help and suggestions are greatly appreciated!


InyoPools Product Specialist  Posted: 8/4/2015 

D - I'm not sure what your pool configuration is. Your pool system cannot allow any air to be sucked into the front end of the pump. With the pool partially flow, are you shutting off the skimmer feed so that air does not enter there. If so, I would check for other air leaks on the suction side of the pump. Most problems are on the suction side and not on the pressure side. Place shaving cream on all your suction connections to locate any air leaks. Shaving cream will get sucked into the leak leaving a depression.

 Posted: 8/4/2015 

My friend had a pool pressure issues.
The pool seems not to have any pressure, but the spa is good.
I took his pump/motor to the NPS store and found that the impeller wasn't any good, so we had that fix plus among other things needed replacement in the pump/motor.
Unfortunately, when I got back the next day, he already had the pool drained completely.
So we filled up the spa instead and ran a test, the pressure was struggling a bit but eventually got pressure and water rotation.
We also filed the pool a quarter of the way but the pump seems to struggle to pull the water up. Previously, the pipe was cracked at the skimmer and he got that fixed. Could it be that issue again? Or somewhere along the by the pressure side? How complicated can this be?


InyoPools Product Specialist  Posted: 7/25/2015 

mhodgson - Sounds like your pool may have a slow air leak in the suction side of the pump. One pool user had a unique way of isolating this leak. He placed shaving cream around any suction side connection that he could get to. The suction leak would pull in the shaving cream leaving a pitted surface.

 Posted: 7/25/2015 

Read all of the great comments but I am about to pull my hair out. I have had my pool for about 18 years and consider myself half way capable of keeping it running. Here is what I am encountering...think I must be missing the obvious...any help or comments much appreciated. 18x36 Heldor Pool. Main drain 8', one skimmer, two returns. Tagelus sand filter/multiport valve. 1-1/2HP Hayward Super Pump (5 years or less old). Pump primes from empty with no problems. All piping from returns repiped (twice) and pump basket fills partially with water although water flow never reaches max to the point that the basket glass shows completely filled. Regardless of MP valve setting, Filter, Backwash, Recirculate or Waste, never really seems to develop enough flow...will show about 5lbs on the gauge and eventually rise after several days when filter needs backwashing. Pump disassembled twice, impeller slightly clogged first time, completely clear second time...both main drain and skimmer lines were cleaned by pool professional about two years ago as part of preventative maintenance. What am I missing? Could pump actually be bad?. Have Polaris PB-460 as well but have isolated it and no change. It runs very poorly since water pressure is not what it should be going into the Polaris pump. Thanks in advance. Mike

InyoPools Product Specialist  Posted: 7/21/2015 

Jason - Normally, when you switch to "Recirculation" mode, you bypass the filter and go right back to the pool. This should eliminate the filter as a problem area but I don't understand why the pressure is changing on your pressure gauge. Check the spider gasket in your Multiport Valve to make sure it isn't damaged. Also check that the impeller in your pump is not clogged - a common problem with low pressure.

 Posted: 7/20/2015 

Decreasing Filter Pressure with no water flow issue

This site contains very helpful info. I am glad I am here. I also have a question and am hoping someone can point me to the right direction.

I have a in-ground pool and Hayward DE filter. I backwashed pool on Saturday night and added new DE . I have done this in the past ten years, and never had problem. This time, the initial pressure was good 8psi as usual. after two hours I noticed that no water returned to the pool, when I checked the pressure gauge, it's zero. I stopped pump and restarted pump. Pressure is now 6psi. In 3 minutes, pressure dropped to zero, and no water returned. I switched the valve to recirculation, initial pressure was 7 psi, after 10 minutes, it's almost zero, and water flow got very weak. I wonder if anyone could help with diagnose the problem. Thanks very much. Jason,NJ.


InyoPools Product Specialist  Posted: 7/17/2015 

kisabels - Did you have any success with the breather tube? Do you have the option of shutting down the main drain to divert more suction to the cleaner.

 Posted: 7/15/2015 

Breather Tube... I will look into that thank you!! Everything else was checked

 Posted: 7/15/2015 

Pool skimmers work just fine but when I change to pool cleaner (vacuum) the pressure drops (spontaneously) and rises from zero to 10 then drops again. At times will stay near zero. Everything above ground has been taken apart and nothing. But the side skimmers work just fine with good pressure. Any ideas?

InyoPools Product Specialist  Posted: 7/15/2015 

txjj - Did you change any of the diverter valve settings that would reduce suction from cleaner port? Too much DE in filter? Breather tube in filter clogged? Impeller clogged?

InyoPools Product Specialist  Posted: 7/13/2015 

txj - From your description it sounds like you have developed an air leak in the suction side of your piping system between the pool skimmer and the front end of your pump. See our guide on "How to Identify and Correct Air Leaks" for some ideas on what is causing your problem.

 Posted: 7/13/2015 

I cleaned the de filter this weekend. Reassembled, back washed, purged air filter, and the pump has no air bubbles in the filter basket. The return or circulation is great but I don't have enough line pressure to operate the Polaris. Sadly it worked great before cleaning the de filter. I disassembled the de filter to double check the manifold and grids were seated correctly and they were. Any ideas what could cause loss of pressure to the Polaris?

 Posted: 7/11/2015 

My pool's water feature seems to 'cycle' on and off.. basically it will flow freely/fully for maybe 10 seconds or so, then slows down until it's no more than a trickle.. repeat. A couple of things I've noticed when this is happening, the water in the skimmer baskets seem low (water gushing in, but not really filling up) and one of the water jets on the side of the pool makes a lot of bubbles that can be heard/seen.

Before I understood anything about basic pool maintenance, I would empty the skimmer baskets and/or the the pump basket, turn the impeller to make sure it wasn't jammed etc. and those types of things seemed to fix the problem for a few weeks. Does this mean there's some kind of air leak that needs to be identified and fixed? Any help or suggestions would be appreciated!!


InyoPools Product Specialist  Posted: 7/10/2015 

Arizona Dan - You may be getting air trapped in the upper part of the filter tank during a regular filter mode start up. This air might be purged when you are in a waste mode. If your filter has a breather tube going from the bottom to the top, see if that tube or the screen on top of it is clogged. Also check that your spider gasket in your MPV is not damaged.

 Posted: 7/9/2015 

This is a very helpful page, thanks. I think I've been here several times now trying to diagnose and fix my problem but so far no such luck... I figured I'd just put it out there and see if you've got any ideas before I call someone. We've been here for six years and never encountered this kind of problem.

I have my in ground pool set to run every night for a few hours so the vacuum and skimmer can do their business. A couple weeks ago, it appeared to stop running. The pump seems to runs fine, but there's no water getting to the filter.

I've checked and cleaned everything I can get to - baskets, filter, impeller, leaks, clogs - and found nothing out of the ordinary. The thing that makes it extra strange is that I found a workaround to get it to work properly. If I pretend to backwash and open that line and run the pump for about five seconds and then close it up and run the pool as normal, then everything is fine. Pressure is good, everything runs properly, etc. And the pool will run for hours without any problem once it's going.

But something in there is hanging things up when it pops on automatically.

Any thoughts? Thanks again for the helpful page and thanks in advance for any ideas.


InyoPools Product Specialist  Posted: 7/7/2015 

T Redshaw - Does your pressure gauge read normal? Check to make sure your pump's impeller has not clogged since you changed your pump's gaskets. Make sure you do not have excessive DE in the filter. Check that your return valves are open all the way. You may have a blocked return pipe. Try blowing out the return pipe with a "Drain King" - bought at a local HW store.

 Posted: 7/4/2015 

I have good suction in pool pump. Very few if any air bubbles. But my pressure side (return line) is weak. I do not see water leakage (no dripping, no spraying) with regards to the pipes exposed (above ground). I do believe I have any air leaks on the suction side due to hardly any air bubbles. Water appears to be clear, good visibility into the debris basket.

I have recently replaced all the o-rings and gaskets to my pool pump, DE filter and even the backwash push/pull valve.

Any suggestions?

I appreciate the advice.


InyoPools Product Specialist  Posted: 6/26/2015 

Patel - Your filter may need to be soaked overnight in a solution like TSP to get it clean. Chemicals like calcium and oils from bathers can become embedded in the pleats of your pool cartridge filter and are difficult to remove with a standard hose cleaning. See our guide on "How To Chemically Clean a Pool Cartridge Filter". If this soaking doesn't work, you may have to buy another cartridge filter.

InyoPools Product Specialist  Posted: 6/26/2015 

Sean - Sounds like either a leak or partial blockage in the main line or its connections. Check any above ground connections dedicated to the main line like the mail line port into the skimmer/main drain diverter valve. If you can't find a leak in the main line,Sean - Sounds like either a leak or partial blockage in the main line or its connections. Check any above ground connections dedicated to the main line like the main line port into the skimmer/main drain diverter valve. If you can't find a leak in the main line, you may have to have someone come in to look at your main drain and the underground piping to the main drain. you may have to have someone come in to look at your main drain and the underground piping to the main drain.

 Posted: 6/24/2015 

I am having low suction in my skimmer. My Hayward 120 sq. ft. Cartridge Filter System & 1-HP Super Pump system is only about 1 month old.
Suction was low so we cleaned cartridge filter and reinsert into system but suction in skimmer is still very very low after.
We took out cartridge filter from the filter system and turned on pump and suction is really good. As soon as we put back filter in suction drop from skimmer.
we cleaned the filter again and reinsert but same result.
I am following all the instructions that are in manual.
Any trick?


 Posted: 6/24/2015 

Thank you for this wonderful resource. Our salt pool is 20x40 and 8ft deep at the lowest point. We have a Hayward Pro Series Sand Filter and the whole setup is nine years old. Two skimmers and a main drain with a diverter valve. When operating skimmers only, pressure at the filter in "Filter" mode is ~12psi. Main drain and skimmers, pressure is ~14psi. Main drain only pressure is 4-5psi and the pump basket never flows freely with water, always bubbles when on main drain only. Sounds like air might be trapped around the multi port valve. Sounds almost like tapping or clicking. Is this indicative of a leak?

InyoPools Product Specialist  Posted: 6/17/2015 

Cva - This is an odd one. Can you isolate the problem to one line by shutting off the skimmer line then turning it back on and shutting off the main drain etc. same for suction line if you have on. Then you at least know what line is perhaps causing the problem. And also check the breather tube in your filter, if it has one. It runs from the bottom of the tank to the top. If it is blocked you may be having back pressure issues.

 Posted: 6/16/2015 

We have 1.5 HP pool pump (Make: Emerson motors model: k63cxepz-4767) along with a cartridge filter, When our pool pump is turned on and running, we notice the suction is not continuous instead its periodic, i mean the water suction flows at once and then its like nothing happens for 30 - 45 seconds and the suction is back again actively drawing lot of water at once and goes back to do nothing for next 30 - 45 secs and it repeats this way forever. I have cleaned the skimmer , strainer basket and removed debris ( 1 or 2 small leaves) also cleaned the cartridge filter , still the same behavior. I’m not sure what else to look for , any inputs will be of great help.

InyoPools Product Specialist  Posted: 6/15/2015 

Mark - Not sure from your question which filter you have, sand or DE but it sounds like your problem is related to the small blue filter on the top. If this filter is the screen filter on top of a breather tube going from bottom to top of the tank, make sure that tube is clear to allow purging of air trapped at the top of the filter.

 Posted: 6/14/2015 

i have a sta-rite system 2 filter. Cleaned started up works for a minute or 2 then bogs down. When we take apart again and clean small blue filter on top works then bogs again no pressure need assistance please