UPDATED: January 22, 2023
You go to your reverse osmosis faucet to get yourself some water and all that comes out of the faucet is a dribble. Then you look at your reverse osmosis storage tank and notice that there is no water in it. And you ask yourself, why is my reverse osmosis storage tank not filling up?
A reverse osmosis storage tank will not fill with water if the air pressure inside of the tank is too high, the reverse osmosis membrane or filters are clogged, or the water supplying the tank has been turned off or restricted.
Some reasons for your reverse osmosis storage tank not filling up may seem obvious but others are not so easy to catch. Read on as I describe all of the reasons that I have found why a reverse osmosis storage tank may not be filling up.
7 Reasons Why Your Reverse Osmosis Tank Is NOT Filling UP.
| Possible Cause | Solution |
|---|---|
| Water supply valve or storage tank valve shut off. | Make sure that the water supply valve that is normally connected to the cold water supply to your sink and the reverse osmosis storage tank valve are both in the ON position where the valve is pointing in the same direction as the pipe or tubing. |
| Check if a leak detector valve has been shut off. | A leak detector will shut off the water supply to a reverse osmosis system when it comes in contact with liquid. check for a leak detector and if it has shut off the water supply to your reverse osmosis system. |
| The air pressure in the storage tank is TOO HIGH. | An air-charged water storage tank that has had too much air added to it will not allow water to fill the tank. Follow the instructions on How To Repressurize A Reverse Osmosis Storage Tank. |
| Clogged reverse osmosis filters. | Clogged reverse osmosis filters will prevent water from flowing through a reverse osmosis system so the water storage tank will NOT fill up. |
| Clogged reverse osmosis membrane. | Hard minerals can go through the filters of a reverse osmosis system and clog the openings in the system’s membrane stopping water from getting to the storage tank. |
| Kinked tubing on reverse osmosis system. | A “KINK” in the tubing of a reverse osmosis system will restrict or even stop the water flow and prevent the storage tank from filling up. |
| Higher than normal water usage. | If you have guests over or more demand for reverse osmosis water, your reverse osmosis system may not be able to keep up because it makes filtered water slower than it disperses water from its faucet. |
Are Your Water Supply And Storage Tank Valves Turned ON?
Did you recently change your reverse osmosis filters? If so, check that all water valves connected to your reverse osmosis system are turned ON.
There will normally be two (2) valves that need to be shut off when changing reverse osmosis filters, one water supply valve that is often installed right after the cold water supply to your sink, and a second valve on top of your reverse osmosis storage tank.
If either one of these water valves is shut OFF, the reverse osmosis system will NOT feed water to the reverse osmosis storage tank.
Even if you have not changed your reverse osmosis filters recently, these valves can sometimes get shut off by being tapped by accident.
While grabbing an item from under your sink or putting one back in you can easily make contact with one of these valves which normally turn very easily and shut the valve off.
Check both the water supply valve and the valve on your reverse osmosis storage tank and make sure that the valve lever is pointing in the same direction as the tubing or pipe connected to it.
Do You Have A Leak Detector Shut-Off Valve?
Even a professionally installed reverse osmosis system can develop a leak at some point so I highly recommend installing a leak detector shut-off valve at the base of a reverse osmosis system.
Take A Quick Look At This Video On How To Install A Leak Stop Valve On Your Reverse Osmosis System!
This leak detector valve will shut down the water supply going to the reverse osmosis system when water is detected.
This is a great preventive measure to protect against leaks from your reverse osmosis system, and if your reverse osmosis storage tank is not filling up because your reverse osmosis system has developed a leak then it was money well spent.
But sometimes a leak detector may detect water or another liquid that will shut down water to your reverse osmosis when it isn’t actually a leak.
Spilling some water while changing your reverse osmosis filters or spilling some household cleaners can trigger a leak detector to shut down the water going to your reverse osmosis system.
Most leak detectors work with a small disc that expands when it comes in contact with liquid to shut the water valve feeding your reverse osmosis system. You should always have some spare discs ready for when you need to replace them in your leak detector.
Check Out This Quick Video On How To Change A Leak Shut-Off Disc!
Is The Air Pressure In Your Storage Tank “TOO HIGH”?
This is one of the most common reasons that people who change their own reverse osmosis filters find that their reverse osmosis tank is not filling up.
This is because when they notice that the flow of water coming from their reverse osmosis system begins to slow down, then they add “TOO MUCH” air into the storage tank which will not allow the storage tank to fill.
Now, you may think that if you put more air into your reverse osmosis storage tank, the flow of water coming out of your faucet will be stronger.
AND YOU ARE ABSOLUTELY RIGHT!
But when the air pressure in a reverse osmosis storage tank is stronger than the pressure of the water going into the storage tank, the air pressure will stop the water from going into the tank!
The air pressure in a reverse osmosis water storage tank must be High enough to push the water out of the tank when the faucet is opened but LOW enough to allow new filtered water from the reverse osmosis system into the tank.
The air pressure in a standard “AIR CHARGED” reverse osmosis storage tank should be between 7 and 8 PSI (Pounds per Square Inch) “when the tank is empty”.
Adding air to a reverse osmosis storage tank that has water in it may result in having TOO MUCH air pressure in the tank for it to accept new filtered water from the reverse osmosis system.
Learn how to properly “Re-Charge” a reverse osmosis storage tank by checking out my article on “How To Represurize Your Reverse Osmosis Storage Tank”
You May Have Clogged Reverse Osmosis Filters!
If it has been a while since you have changed your reverse osmosis filters, your storage tank may not be filling up because your filters are preventing water from getting through your reverse osmosis system.
Although the post-filters can sometimes get clogged, the most common filter to get clogged in a reverse osmosis system that would prevent water from getting into your storage tank is the first filter, or the (Pre-filter).
The filters do not have to get so clogged that they will not allow any water through the reverse osmosis system, they just have to get clogged enough to restrict the water pressure enough so the water does not have enough pressure to fill the “pressurized” tank.
If you have checked for shut-off water valves and have made sure that the air pressure in your reverse osmosis storage tank is correct but still has no water getting into your storage tank, check your reverse osmosis filters and change them if they appear at all clogged.
Learn how to and how often you should change your reverse osmosis filters in my article “How Often Should I Change My RO Filters“
Your Reverse Osmosis Membrane May Be Clogged With Hard Minerals.
You have checked for closed water valves and you recently changed your reverse osmosis filters but your reverse osmosis storage tank is still not filling.
If you have changed your reverse osmosis filters but have NOT changed the reverse osmosis membrane for quite a while, the membrane could be clogged by hard minerals in your water.
You may not need a water softener because your water is relatively soft, but even a low amount of hardness in your water can cause a reverse osmosis membrane to clog.
Hard minerals will pass through a standard reverse osmosis pre-filter but will get captured in a reverse osmosis membrane.
Over time, the membrane will capture enough hard minerals for it to prevent water flow through the membrane.
This does not mean that you need to have a water softener to use a reverse osmosis system, but it may mean that you will need to replace the reverse osmosis membrane more often because it may get clogged with the hard minerals in your water.
Check Your Reverse Osmosis Systems Tubing For Kinks.
Unless you have moved your reverse osmosis system around or have moved items around it recently, your reverse osmosis tubing should be fine.
But sometimes the tubing of a reverse osmosis system can get “KINKED” when it is bent at too sharp of an angle.
This can cause the water flow to slow down or stop which can prevent your reverse osmosis storage tank from filling up.
A bend in the tubing will not cause any water restriction, but if the tubing takes a sharp turn a “KINK” can occur and stop the water flow.
Make sure that all of the tubings for your reverse osmosis system are relatively straight and free of obstructions. A simple turn of the storage tank can cause the tubing to “KINK” but simply turning the tank back can eliminate the “KINK” in the tubing.
To Sum Up!
A reverse osmosis storage tank NOT filling up is normally due to the water being restricted or shut off before getting to the tank, or the pressure inside of the storage tank is TOO HIGH for the water to fill the tank.
Check for these common problems that lead to a reverse osmosis storage tank not filling and I believe you will find your answer.
I recently changed all three filters and disinfected my r.o. System and can’t get my tank to fill, the water also doesn’t taste like ro water out of the faucet. I have checked water pressure, tank pressure, kinks and lines are unclogged. Any ideas why this would happen after the filter change? How do you know when you need a new ro system? It is a AQPC-35 from aqua systems, thanks for your help!
Hello Patrick and thank you for the question.
The first two things that I would check would be that the membrane in the center is in properly and make sure that the drain line is not clogged or out of alignment.
If the Oring on the membrane is not seated properly, you could be getting unfiltered water flowing past the membrane and not through it. If the membrane does not go in easily, put on some latex gloves to prevent oils from your skin from damaging the membrane and remove it and make sure that the rubber Oring and seal are intact and clean.
When you replace the membrane, it should go in quite smoothly, and be sure that you keep it very straight when you put it back in to prevent the Oring from pinching.
Secondly, shut off the water to the system and remove the drain tube that is going into your drain saddle on your drain pipe. Take a skewer or awl and gently make sure that the opening going into the drainpipe is clear. If the drain line gets clogged, the rejected water from the system will end up coming out of your drinking faucet.
Before you put the tubing back into the drain saddle, hold it in a bucket and turn the water to the system back on and run some water from the faucet to trigger the system to make new water (Having someone help you with this is handy).
Once your system starts to make water, you should see water coming out of the drain line and into the bucket. Let it run for 30 seconds or so until you are satisfied that it is running clear and then shut off the water and reinstall it into the drain saddle.
You might want to double-check that your storage tank pressure is between 7 and 8 psi (WHEN EMPTY) at this point.
Turn the water back on and turn on the faucet for a minute or so to make the system make new water. Shut off the faucet and you should hear some water from the system draining into your drain pipe.
Then, I would leave the faucet ON for ten minutes to allow the water to purge. Shut off the faucet and let the system make water for 3-4 hours and then check the tank and try the water.
If there is no improvement in the water and the tank does not fill, there could be a problem with the auto shut-off, or the drain flow restrictor may be clogged.
Check out this product manual I found HERE for more details.
I hope this was helpful!
Paul
My RO system had been shut off for a while and now no water coming out at faucet. No water in tank but do see a small amount of water coming out the drain line. Checked pressure in tank 5lbs. Let system run for a while and still no water in tank or comes out faucet. Just note my system hasonly been installed for a short time, 5 months then was shutdown for 2 months
Hello Wayne and thank you for the question.
The pressure in the tank should be between 7 and 8 psi when completely empty but low pressure in the tank would not prevent the tank from filling. Make sure that the valve to the storage tank is completely open and that there are no kinks in the tubing.
If everything looks ok, you may want to shut off the water to the reverse osmosis system, remove the tubing going to the tank, point the tubing into a bucket, then turn the water back on to verify that water is being fed to the tank.
If there is no water getting to the tank but there is still water flowing out of the drain line, the auto shut-off valve may have seized and needs to be replaced. An auto shut-off valve doesn’t normally go bad very quickly, but since the system has been shut down, it may have seized.
Since not all reverse osmosis systems work exactly the same, I would contact the manufacturer’s technical service department to verify that it is the auto shut-off valve and ask them if it is covered under warranty.
I hope this was helpful.
Paul
I recently have santized my RO system by buying the solution pouring it in the first cartidge and Turing the water on. I did take out the filters first. After that i installed new filters plus membrane and turned the water on. Ever since then my tank has not refilled at all. I’m not sure if I installed the filters to early before i drained the tank again (to get the solution out) and it clogged the membrane or mabye the air bladder in the tank went bad. I’m lost. I did repressured the tank to the recommend psi and still tank not filling.
Hello Sebastian and thank you for the question.
I don’t believe that the sanitizer solution caused any problems with your system. If you run water through the system after adding the sanitizer, the sanitizer should be completely out of the system and it normally would not clog any filters or the membrane.
I would check out my article How To Repressurize A Reverse Osmosis Storage Tank to make sure that the storage tank is working properly and then allow the system to attempt to fill the tank overnight. If the tank still does not fill, then you may need to check for clogged filters one at a time but I find that it is more often the tank than the filters that would be the problem.
I hope this was helpful.
Paul
Hello Paul,
My RO system started producing a very little amount of water. So I replaced the filters, the tank and the auto shut off valve due to solutions I found on the internet but it still doesn’t seem to be making any water. There is very little water in the new tank I just bought as well. I don’t know what else could be wrong as to why I am not getting any water from the RO faucet.
Hello T-Anna and thank you for the question.
Although different reverse osmosis systems can have different reasons for lack of water production, I do have some thoughts on what you may want to check.
First of all, your new storage tank should have come pre-pressurized from the manufacturer so it should be fine, but if all else fails, check out my article “How to re-pressurize a reverse osmosis storage tank” to make sure that it is pressurized correctly.
Did you also change the reverse osmosis membrane when you changed your filters? Even though the filters of a reverse osmosis system help to protect the membrane from clogging and getting damaged, a membrane can become clogged and reduce water production. Minerals that make water “HARD” like calcium can pass through the filters in a reverse osmosis system and clog the membrane (even though the membrane may look clean) which will stop water from flowing through the systems membrane.
This will leave the storage tank nearly empty because the incoming water pressure from the membrane is too low to fill the tank.
If you have hard water or even occasional hard water because your water softener ran out of salt, hardness can build-up on the reverse osmosis membrane and stop the water flow.
There could be a restriction before the system preventing ample water pressure to the system. If you shut off and disconnect the supply line to the system and then point the line into a sink or bucket and then turn the water back on to see if the water pressure is strong.
Some more elaborate reverse osmosis systems have additional valves or stages that could restrict water flow through the system. If your system has extra features, you may need to contact the manufacturer of your local dealer for diagnostic assistance but I would check the incoming water pressure and change the membrane first.
I hope this was helpful!
Paul
Hi Paul,
You like a mystery? Here are the clues:
Filtered under-sink RO system water volume started decreasing. Had all water filters and RO membrane replaced. Didn’t change anything, but I let it go for a while. I finally got off my butt and emptied the RO tank and the PSI was low, so I pumped it up to spec. Same problem. Tank not filling up all the way (noted by output and weight). Got new tank. PSI checked out. Same thing. Got yet another tank. PSI was good. Same thing. Hmmm.
No kinks in tubing I can detect. All valves in full on position. House PSI good. No waterlogged leak-detector puck. Whole-house water softener with salt upstream. The quart or three of water that does come out is fresh and clean. I’m stumped. You?
Thanks.
Hello Rich and thank you for the question.
It sounds to me like the “Auto shut off” on your system may be sticking so that it does not turn on completely which makes it shut off before your tank has properly filled.
I would locate the auto shut off which has 4 tubes going in and out of it and replace it.
I hope this is helpful
Paul