You love having your reverse osmosis system. You have great tasting water whenever you want it. But lately, it seems to be taking forever for you to just fill one glass of water from your RO faucet, what’s going on? Well, it may be as simple as your pressure tank being low on air pressure.
To repressurize a reverse osmosis water tank, follow these simple steps.
- Turn off the valve on the reverse osmosis system supply line.
- Turn on the reverse osmosis water faucet and let the water run until it comes to a complete stop.
- Give the water storage tank a shake to make sure that it is empty.
- If the tank still has water in it, locate the air valve on the tank that is just like one on a bicycle tire and give it 6 pumps of air with a bicycle pump and let it empty.
- Check the pressure of the emptied tank with a low-pressure tire gauge.
- Adjust the pressure to 8 lbs by adding air with the bicycle pump and checking it with a low-pressure tire gauge.
- Return the tank to its original position and turn the water supply back on.
- Shut the reverse osmosis faucet off and let the tank fill-up for 3 hours.
- Continue to enjoy your reverse osmosis system as usual.
Much like the tire on a car, the rubber bladder on the inside of a reverse osmosis storage tank can lose pressure over time.
Re-pressurizing the storage tank is done by simply emptying the tank and adding air to it like a bicycle tire to the correct pressure so the water can fill and dispense correctly.
Your only going to need a few simple items to re-charge your reverse osmosis storage tank that you may already have in your home. You will need a pair of pliers or adjustable wrench, a bicycle tire pump, and a low-pressure tire gauge.
If you are going to do any work on your reverse osmosis drinking water system, check out my article on What I Use When I Work On A Reverse Osmosis System!
If you don’t have a low-pressure tire gauge handy right now, I will show you how to get your water flowing again without one, and then you can come back when you get one and we will get it working even better.
The reason that we want to use a low-pressure gauge is that there is a rubber bladder inside the tank that needs to be under the correct pressure so it can allow the water pressure in your home fill the tank and then have enough pressure to dispense the water from your reverse osmosis faucet.
Too much pressure and the tank will not be able to fill, too little and it won’t be able to push the water out.
The pressure in the tank needs to be measured when the tank is completely empty, so let’s start by shutting off the water supply to your reverse osmosis system.
Most reverse osmosis systems will be getting their supply of water from the cold water supply directly under the sink where the system is located. The shut off is often a white-colored fitting that has a blue lever on it. This lever just needs a quarter turn, and the water to your system should be shut off.
Before we continue, let’s check to see if the reverse osmosis storage tank is waterlogged. This means that the tank is totally full of water when it should have both water and air in the tank.
Give the tank a little shake, if it feels like it has nothing but water in it, there may be a hole in the tank’s bladder and therefore will need to be replaced. So if this problem reoccurs shortly after we finish repressurizing the tank, it is likely that the tank will no longer be able to properly dispense water and should be replaced.
Now that the water is shut off, turn on the reverse osmosis faucet, and let it run until the water stops. Once the water has stopped, we are going to look for a similar-looking shut off lever that should be located on the top of the storage tank. Turn this second lever a quarter turn, just like the water supply lever that we shut off under the sink faucet.
Now the storage tank should be completely empty, pick up the tank and give it a little shake to make sure. It should be very light and you should not feel any water moving around inside the tank.
If there is still water in the tank, simply unscrew the plastic cap that covers the Schrader valve (a fancy name for the valve that you would see on your car tire or on a bicycle tire) with your pliers or adjustable wrench.
Now, attach your bicycle pump to it and give it about six pumps. Then turn the valve on top of the tank back on and you should see the water come out of the faucet again. Let the water flow until it stops completely, and then check to see if the tank is empty.
Now shut the valve on top of the tank off again and shake the tank again to be sure that it is empty. The tank should feel as though there is nothing but air inside.
What if I can’t get all of the water out of the RO tank?
If you have added air to the storage tank and there is still water in it that won’t come out, the tank’s bladder may have a hole in it.
Without an intact bladder that can hold air on the outside of it and water on the inside, the air can’t force the water out of the faucet for you to use.
Although in some reverse osmosis storage tanks, the bladder can be replaced, most of the time you are better off just getting a new storage tank.
A new reverse osmosis storage tank is not very expensive, they come pre-pressurized and are very easy to replace. All you will have to do is shut off the supply water going to the system, then shut off the valve on the old storage tank, then turn on the reverse osmosis faucet until the water stops.
Next, remove the tube that is connected to the storage tank by pushing it in about 1/8 of an inch, then hold back the retaining ring that holds the tube in place and then pull the tube out.
Put the new tank in place, make sure the tube is free of burrs or cuts and insert the tube into the new tank. If the tube has burs or cuts, carefully cut back the damaged area, clean off any burrs and then insert it into the new tank.
The new tank should be all set to go but I recommend letting it fill-up for about 3 hours and then emptying it out at least once to be sure that it gets thoroughly rinsed out before you start drinking the water from it.
If you have replaced the storage tank then you are all done, but if your existing tank emptied out completely, then we need to get it to the correct pressure.
Now, use a pen or other small semi-pointy object to press the pin in the center of the Schrader valve down, you should hear the air escaping from the storage tank.
Hint: Often, the low-pressure tire gauge will have a small bump on it which is used to release the air from the Schrader valve. Just press it inside the valve to release air from the tank.
Once you have let all the air out of the tank, put the low-pressure tire gauge on the Schrader valve to make sure there is no pressure left in the tank. If you don’t have a low-pressure gauge, just press the pin down until you no longer hear the air escaping and that should be fine.
Now, put the bicycle tire pump back on the tank, and give it about ten pumps. Remove the pump and use the low-pressure gauge to find out how much pressure we have in the tank.
Most standard reverse osmosis tanks are three to four-gallon tanks that work best when the pressure in them is between six and ten pounds per square inch (PSI), so the magic number that we are shooting for is eight pounds of pressure.
Continue adding a few pumps, then checking the pressure until the tank is pretty close to eight pounds of pressure. It doesn’t have to be super exact, a little bit above or below eight will work just fine.
What if I don’t have a low-pressure tire gauge?
If you do not own a low-pressure tire gauge, empty the tank in the same way as described, and then attach the bicycle tire pump and give the tank about fifteen pumps. This should be enough pressure to make your system work until you can get a low-pressure tire gauge.
Do not over pressurize the tank as this will not allow water to go into the tank. Fifteen pumps should do just fine for now.
Once we have our pressure where we want it, you can put the Schrader valve cap back on and put the tank back where it belongs.
Now that the storage tank is back in place, we can turn the tank back on by turning the valve back one-quarter turn as it was before. Next, we need to turn the supply valve on as well. Give the water valve a quarter turn back to its original position, and the water should be back on.
Leaving the faucet on, you should soon see some water start to dribble out of the faucet. The flow of water will be very slow compared to the flow when the system is working normally.
This slow flow that you see when you first turn the system on is how fast the reverse osmosis system makes the filtered water. Once you see that there is water flowing from the faucet, you can now shut off the faucet.
Once you have shut off the faucet, the system will start to fill the storage tank. It may take several hours for your storage to fill so don’t be alarmed if you try to get some water to drink soon after emptying the storage tank and you don’t get as much as you normally would get.
After a few hours, the storage tank should be mostly full and you can go back to normal use. If you find that your only getting a small amount of water after a few hours, let the tank fill overnight, it may just take some more time to fill the tank.
If you only get a small amount of water after you have let the tank fill overnight, you may have put too much, or too little pressure for your particular tank.
Follow the instructions again and shoot for seven pounds of pressure instead of eight. If you don’t have a pressure gauge, put in ten pumps rather than fifteen.
Now your reverse osmosis systems storage tank should be able to fill with plenty of water and also dispense it with a good steady flow.
Be sure to change your reverse osmosis filters every twelve to eighteen months, and test your reverse osmosis water with a TDS meter a few times a year to make sure that your drinking good filtered water.
Remember, the total dissolved solids count from your reverse osmosis system water should be about ten percent or less of the total dissolved solids count coming out of your regular cold water faucet. If it is not, it may be time to change your reverse osmosis membrane.
Related Questions:
Can I use a larger reverse osmosis storage tank? There are many sizes of water storage tanks that could be used with most reverse osmosis drinking water systems.
They generally range from as little as 2 gallons to as much as 20 gallons. While most reverse osmosis storage should work right out of the box, some may require a minimum amount of incoming water pressure to be used to their full capacity.
Before attempting to use a storage tank that is considerably larger than the size that originally came with your RO system, check for minimum pressure requirements needed for it to perform properly.
I find that using 2 smaller tanks connected together with a “T” connector works very well and will provide plenty of water for the average household.
Do I need to have my reverse osmosis storage tank right next to my reverse osmosis system? Putting a reverse osmosis storage tank in another room or even another floor can work fine providing that the storage tank can produce enough pressure to force the water out of the tank and to the faucet.
Having the storage tank several feet away on the same floor will usually not affect the system’s performance, but having the storage tank a full level below the faucet to be used may cause a slow rate of flow and the tank may not be able to discharge its full capacity of water.
Hi:
Is there a way to test (the bladder in) a tank?
If the bladder is leaking, how long should/would it take to de-pressurize?
I thought I would leave it at a set pressure for a day and check it to see if it loses pressure.
Would like to ensure the tank is OK before re-installing.
Around July-August 2019, the faucet would start dispensing water at a normal rate for a few seconds and then gradually slow down to a trickle. Waiting about one minute, it would repeat the process: starts with strong flow and diminishes.
Did not realize it had been so long since I installed the RO system–May 2016! (Only two of us and have not noticed any change in the filtered water.)
So, have taken all (4) filters and membrane out and will be replacing.
Tank was full of water (took out more than 2 gallons).
Got the water out by opening the top valve and adding compressed air when the flow slowed.
Took the valve out (using a tool from an old bicycle tire repair kit) and emptied the air bladder.
Put about 8 lbs. in, but I think I put higher pressure when getting the water out. Filled it from a portable tank, little bursts and withe the valve almost closed as not to damage the bladder.
It had about 35 lbs. of pressure when I first disconnected it and it was full of water. Which I read somewhere it is about right.
Would appreciate any comments or ideas on testing the tank.
Thanks in advance!
Hello Etienne and thank you for your question
I don’t think that there is anything wrong with your tank from what you have described.
A reverse osmosis storage tank can lose pressure very fast if there is a flaw or seal that is not holding, but this is not very common.
A three-year-old tank is not likely to need to be replaced, but it certainly may be low on pressure.
I think that the tank has been losing pressure steadily for a while, but since there is only two of you using it on a daily basis, you didn’t notice it until it got to the point where you are getting less water than you regularly would use.
When you emptied the 2 gallons from the tank, it was probably not able to dispense the whole amount of water in the tank already. In other words, it was dispensing a small amount of water and then refilling, so you never noticed that you could not get all of the water out.
When you removed the valve, you removed all of the NEW air that you had recently added, but there was very little air in the tank when you first noticed the problem.
I suggest that you empty out the tank bladder, and then release all of the air. Then use a low-pressure tire gauge to bring the air pressure to 7-8 pounds of pressure (with the tank emptied of water). This should be enough pressure to use all of the water that the tank can hold.
Check the pressure each time that you change your filters, and the tank should last for many years. Also, you may want to sanitize your reverse osmosis system since the tank has likely has not been emptying properly for quite a while.
Hope I was able to help.
And thank you for the question.
Paul
Hi – you forgot to add the most important first check – see if your system has a safety shut off valve (like ours does), the cotton swap got wet from a failing food dispenser and swelled up and cut off the water supply/pressure. Removed it – popped switch back down and the pressure is back and tank is filling.
Just a heads up
Hello Francois and thank you for the comment.
That’s a very good point, I will be sure to add that to my article soon. For those of you that are not familiar with the Safety Water Shut Off Valve that we are referring too, you can install a 1/4 inch tubing sized water shut off safety valve that will shut off the water going to your reverse osmosis system when it gets wet.
Check out my Recommended Leak Detectors for more information!
Paul
Can the storage tank be placed on its side rather than straight up? Due to lack of space ours was installed 13 years ago and laid on its side. Recently changed filters. Water flow was good for a few seconds and then slowed to a trickle. In. Turned off the supply and added air to the bladder and was able to empty the water. Then when we turned on the faucet the water was discolored sort of murky.
After a few cups the water became clear. Reluctant to drink until I can find out why. Any suggestions?
Also, our system is a Dupure system. I understand the only difference is that the thread for the filters is opposite of all other systems (LH thread) is there any kind of an adapter to be able to use other filters that sell for less money.
Hello Bob, and thank you for the question.
An air charged storage tank certainly can be placed on its side, and it will work just fine, but it can reduce the life of the bladder. See my article “Can A Reverse Osmosis Tank Go Bad”
It sounds to me like your tank has not been emptied for a long time causing the murky looking water. I suggest that you follow the steps to re-pressurize the tank and then check out my article “How do I sanitize my reverse osmosis system” to clean the inside of the tank to make the water clear again.
If you find that the tank bladder has gone bad, you can find a new one here.
I don’t know of a way to use standard filters for a Dupure system, many manufacturers only allow you to use their filters for their systems.
I hope this was helpful.
Paul
Paul, thank you! Your reply was extremely helpful. I’ll be back.
Thanks Again, Bob
You are very welcome Bob, I am happy to help. Be sure to share freewateradvice.com with your friends.
Have a great day!
Paul
Thank you for another informative site. Where else could I get that kind of information written in such a perfect way? I have a project that I am just now working on, and I’ve been on the look out for such great information like yours. Thanks!
Hi. Your site is very helpful. Thanks!
I just got a new refrigerator that has a door-mounted water and ice dispenser. I thought I’d be clever and hook it up to my reverse-osmosis under the sink system. It works, but it only makes about 1/3 of the ice cubes that it should. The fridge manual says that might happen if the filtration system doesn’t supply enough pressure. Could I just pump up my tank a bit?
Hello Mr. Beichner and thank you for the question.
Adding more air pressure to your reverse osmosis tank may make the water flow stronger if the tank has lost pressure but just adding more pressure may over pressurize the tank which will not allow as much water into the tank and not help the outgoing pressure.
If you have connected your reverse osmosis system to your refrigerator you no longer need to have the filter that is in the refrigerator, it will restrick the flow.
Check your owners manual on removing the filter, you may need to order a bypass filter or “dummy filter” to replace the filter. This will allow the best flow into the refrigerator.
If your refrigerator is more than 8 feet from your reverse osmosis system, it may be having a tough time getting the water into the refrigerator quickly enough to totally fill the ice maker. Adding a small secondary reverse osmosis storage tank right before the refrigerator can help supply the refrigerator ice maker, and you only need a very small tank 2 gallons or less.
Make sure your pressure is correct (but not too high) in your storage tank and if that is not enough to do the job, try a small second tank right by the refrigerator.
I hope this was helpful.
Paul
Hi Paul,
My under sink RO’s , GE model GXRV10ABL01, water output had dropped to a very few drops over the years. After reading the manual and posts on the Internet, I ordered a restrictor, and set about to replace it. The replacement was not the same as the original, and the original was clean, etc, so I put it back together. In addition, I tried to measure the tank air pressure, as described in literature, by draining the water and using a low pressure air gauge. I had 0 PSI , so to be sure, I depressed the Schrader valve carefully, but got no hiss at all. I tried to add air to it using a small compressor, but no luck. Thinking that it was pressurized another unknown way, I put the system back together and turned on the supply water. I could hear the tank filling and the air gap began discharging water. After a couple of hours, the tank barely made a noise, so I pressed the faucet lever. Water came out terrifically. Just checking the amount available, I let it run for a short time. Air began to blow out with lots of air bubbles, water, etc. Thinking for some unknown reason I was fixed, I let it run for a long time, but the air gap water never stopped. Realizing I was not through, the next day, I removed the tank again, drained it, and tried to force more air into air port. It didn’t happen. Eventually, I took it to the larger compressor and tried it again, but with no positive results. I removed the Schrader valve, but no improvement. There was a note on the tank stating a certified technician was needed to set the air pressure, so I wondered if something was different inside the air bladder. Using a small, flat-ended Torqz bit driver, I gently probed the inside of the bladder through the Shrader valve opening. I felt a couple of soft spots, which I felt was probably the bladder material. Also, between the soft spots, I felt a hard spot like metal. I pushed in on it but it barely moved, so I thought it was a high pressure adjustment, but didn’t try to adjust it. I put the air hose on the Schrader valve opening again, without the valve, and tried to squirt air into it, but nothing. I saw a pressure on the tire gauge of 60 PSI. Not knowing what to do, I put it all back together, and tried it this morning; unsurprisingly, the results were the same.
So, the hoses, restrictor, valves, and all are reassembled correctly, and no water runs out the air port.. The air gap won’t stop running. The faucet puts out a small dribble of water. I’ve not tried higher air pressure. Questions:
1) How does one pressurize this tank and to what pressure,
2) Why did it have great pressure and a large quantity of water the first time I put it back together, and
3) Why doesn’t it now?
Thanks for any help.
JimBo
Hello JimBo and thank you for the question.
I have come across reverse osmosis tanks where the water bladder has gotten stuck to the sides of the tank because the tank was on its side, the bladder had shifted to one side or there was very little water used at any one time so the blader was always expanded.
I recommend using a bicycle pump to control the proper pressure in your tank. A standard reverse osmosis storage tank will work best at about 7-8 PSI but may not work very well at all if you add too much pressure. At 10 PSI the bladder may not expand very much at all and you could only get a few ounces of water stored in your tank.
I believe that you had good pressure because when you took the system apart, you depressurized the auto shut-off valve which allowed your tank to fill properly once, and then the auto shut-off valve did not operate properly after that because it was under pressure again.
You may need to replace the auto shut-off valve but I would first replace the storage tank because the bladder seems to be malfunctioning.
I hope this was helpful.
Paul
my ro system (Kenmore 30 gpd) was installed new approx 8 years ago – by the plumber that plumbed my condo. One thing strange he did was install the storage tank horizontal. (1) Should this be changed to a vertical installation? The system now delivers very low water supply – approx 1 pint and the flow in nothing. quart. I can not force air into the tank. (2) Will it help to drain the tank and then pressurize to 8 psig?
Hello Mr. Baldwin and thank you for the question.
A standard air-charged reverse osmosis storage tank can be installed either vertically or horizontally. Because the tank works by air pressing against the outside of a rubber bladder, the pressurized air will press on the bladder if it is vertical or horizontal.
In some cases where the water bladder has been laying to one side for a very long time without filling and emptying regularly, the bladder may wear or stretch unevenly, but this is rare and takes many years for this to happen.
If you are not getting very much water from your storage tank, I would highly recommend emptying the tank and checking the pressure with a low-pressure tire gauge, then recharge the tank to 7-8 PSI. Most tanks will work just fine between 7 and 8 PSI but higher pressure may not allow enough water into the tank.
I hope this was helpful.
Paul
Hi Paul,
My 10-year old reverse osmosis system had slowed to only dispensing a cup of water at a time, I thought I would have to replace it but after following your instructions it is good as new! Not sure why this information isn’t in the owner’s manual, it’s a relatively simple procedure. I appreciate you sharing your expertise.
Regards,
Mike.
Hello Mike, and thank you for the comment, glad that I could help.
Paul
hello Paul I pressed on the air valve and water came out is that normal
Hello Mario and thank you for the question.
There should NOT be any water coming out of the air valve of a reverse osmosis storage tank.
If you are getting water out of the air valve, there is either a hole in the tanks’ water bladder or a break in the seal where the bladder connects to the tank opening.
Sometimes water can leak out from the bladder when the air pressure gets low. Try to pressurize the tank as described in my article and then see if the water stops. If so, the tank may be fine for now. But if the water continues to come out of the air valve, the bladder is leaking water and you will have to replace the storage tank.
See my Recommended Storage Tanks
I hope this was helpful!
Paul
Can I use nitrogen to re-pressurize the tank?
Hello Tina and thank you for the question.
I really don’t know if nitrogen will work quite the same way as regular air.
Nitrogen is very different than normal air and might not allow the water bladder to fill properly or it may not force all of the water out of the bladder.
I would recommend using air from a standard air pump.
I hope this helps.
Paul
Good stuff! I repressurized my system this evening.
You’re welcome Ronald, glad I could help!
Paul
I have a 5 filter RO system that I’ve had for 20 years! I changed all 5 filters last week and since, when I turn the RO water on it starts strong and then goes to about half strength. I found your excellent explanation of adjusting the pressure but when I attach the bike pump the air can’t get in to the tank. I pressed on valve and there was no sound of air ( I would think that means it’s empty). I’ve tried a few different bike pumps. When I changed the filters I opened the faucet to empty the tank and about 5 ounces of water came out. I don’t get it. Somehow the water is going through the tank but the tank has no pressure? Help!
Hello Michael and thank you for the question.
I believe that your tank might be just fine it just is completely full of water. If you shake it and it feels like it is full of water you may need to shut off the tank, disconnect the tubing and remove the tank so that you can lay it on its side over a sink to remove the water.
Lay the tank on its side with the valve over the sink, open the valve and then use your pump to add some air to the tank (make sure that the pump is pushed down on the valve) and you should see the water start to come out.
Remove ALL of the water from the tank and then follow the instructions in my article How To Repressurize A Reverse Osmosis Tank
Hope this was helpful
Paul