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.

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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.

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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.

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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


(361 to 373 of 373)

 Posted: 6/21/2014 

Thanks "InyoPools" it was the filter.....I soaked it overnight in a solution of TSP, and the water was greenish-brown when I checked it this AM. Also when I washed it out with the hose, there was alot of darkish color water coming off of it.

When I reinstalled in the system and turned it on, there was plenty of circulation power, just like I remember from when it was new.

Thanks again!!!


InyoPools Product Specialist  Posted: 6/19/2014 

dmoore77 - Apply a soapy solution around the suction side connections before the pump to see if any bubble get sucked into a leak when the pump is running. If your filter has a breather tube going to the top of the tank, check that that is not clogged. Lastly you may have a chemical block build up in the folds of your filter that's hard to clean out with a hose. Try soaking your cartridge in a TSP solution overnight.

 Posted: 6/19/2014 

I found another although less likely source: check the pump pre-filter basket for cracks. At first this may seem counter-intuitive (i.e. a crack should let more water thru), but it can have the opposite effect as well. My pump normally runs at 18-20 PSI, but had lately been running at around 10 PSI. While troubleshooting the supply side, I discovered a 3-4" vertical crack in my basket right in front of the opening to the impeller. This crack (along with some leafy debris) was causing the basket to 'flex' when under suction load, effectively closing the normal gap that exists between the basket and housing. This flexing effect restricted the flow to the pump inlet and caused the pressure drop. Replacing the basket with a new one fixed the problem.

 Posted: 6/19/2014 

My pressure gauge is reading between 15-20 on a regular basis. Water flow, when it is reading these numbers is slow. When I clean the filter, it usually will go back to about 10 and the flow appears normal, but definitely is increased. It will stay that way for 3-6 hours, but then the gauge will begin showing an increase going back up over different amounts of time (sometimes quickly & sometimes gradually). I see no water leaks anywhere. I also cannot get much suction to vacuum pool.

Skimmer & strainer baskets are clean, filter is fairly new, and I checked the gasket on strainer (OK), and checked/cleaned impeller. I also replaced the pump motor & seals just a few weeks ago.

I am noticing a few small bubbles coming out of two different returns.

Any other suggestions????? Thanks!


InyoPools Product Specialist  Posted: 6/18/2014 

craftycatey - I'll assume that the pool professional checked for a clogged impeller and rule that out. If your pump has full prime, you don't have a suction leak. About all that's left is a clogged pipe or hose on the suction side. Have someone check the suction piping.

 Posted: 6/16/2014 

I've tried it all...even took everything (pump and D.E. filter/fins) in to the 'pool professional' who agreed they were all fine. Purchased new D.E. and new pressure gauge, but still no circulation. Pressure gauge reads about 5 pts. higher then previously, but not able to vacuum or circulate chemicals. Cleaned the fins with solution, worked for 1/2 hr. then back to no ciruclation. Any ideas?

InyoPools Product Specialist  Posted: 6/13/2014 

Ethan - A clogged impeller is a common problem. See our guide on "How To Clean Out a Pool Pump Impeller".

 Posted: 6/12/2014 

My pool jets used to shoot water out and make the pool like a river now all the sudden it barely moves the water my pool doesn't have any movement at all I've tried cleaning filter and chemicals now every week it turns greens again because of this problem any solutions?

InyoPools Product Specialist  Posted: 6/6/2014 

Newpool - It sounds like algae is still clogging your filter. If you have a suction port, try suctioning any algae remaining at the bottom of your pool out through the waste port - bypassing the filter. Then take your filter grids out and hose them down good to get any remaining algae out of the grids. Add new DE.

 Posted: 6/4/2014 

We are new pool owners and trying to figure out why the returns and skimmer don't maintain pressure. We have cleaned the DE filter and replaced DE. There are no bubbles in the pump filter. We've tried back washing as there is still a bit of algae at the deep end after opening the pool a week ago. After each backwash the returns run well for about an hour but then begin to lose pressure. Water level is good. PSI does rise about 5 Pts as the returns start to weaken...but again goes back down after back washing. Thoughts on what the issue might be?

InyoPools Product Specialist  Posted: 6/2/2014 

elfiador - Make sure the cartridge is seated all the way down when you place it in the tank so that the tank cover is able to all the way down. If that is not an issue, it could be that you have a partial block in the piping or pump that reduces the pressure enough to not work with the cartridge in.

 Posted: 5/31/2014 


 Posted: 5/26/2014 

Very good article, at mine was step 10, incredible after a few month tryng to find the problem in a monday evening i found this article and here are two thre step more ,
Finaly i replace the pressure indicator whith new one and it worked