Reverse Osmosis System Not Producing Water? Here’s How to Fix It
Written by: Alexandra Uta // Last Updated: Jun 28, 2023
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Reverse osmosis systems are complex multi-stage filters, and as such, they’re prone to occasional issues. An RO system not producing water can be especially frustrating, but it’s important to realize that most of the issues causing this have simple fixes.
You’ll need to identify the cause of your problem, which will require a little trial and error. Once that’s done, you can go about fixing it.
Let’s take an in-depth look at the potential problems leading to your system not producing water, plus how to fix them.
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Key Takeaways
If your reverse osmosis stops producing water out of the blue there are several potential causes. Some of the reasons for an RO system not producing water are
- a turned-off power supply,
- turned-off feed water valve,
- too low or high pressure in the storage tank,
- high water usage,
- a ruptured tank bladder,
- clogged filter elements,
- very low water pressure,
- a malfunctioning flow restrictor or auto-shutoff valve,
- kinked tubing,
- poor feed water quality,
- or cold source water.
The solution for these issues varies, many can be fixed on your own with relative ease, while others require more complex fixes.
Reasons for Your Reverse Osmosis System Not Producing Water + How to Fix
A RO system that stops producing water suddenly is a clear sign that something is wrong. The reason behind this can be relatively minor, like a simple valve turned off, or it could indicate a more serious problem…
Power Supply to the RO System Turned Off or Broken
Some RO systems use a booster pump to increase the water pressure flowing into the system. If the pump’s power supply is disconnected or broken, then the pump will stop functioning. For some systems, this can lead to the system not producing water at all.
The solution to this is fairly obvious – simply plug the power supply back in and allow the pump or other electrical component to start working again. If the power supply is broken it will need to be replaced.
Feed Water Valve Turned Off
The feed water valve is the valve that supplies the system with water. In under sink systems, it’s connected to the cold-water supply running to your kitchen sink. If this valve is shut off, which can happen after replacing filters or servicing the system, no water can enter the system.
To fix this issue, simply open the feed water valve all the way, allow some time for the tank to fill, and then open the RO faucet to see if your problem is fixed.
RO Storage Tank Pressure Issue
RO storage tanks use internal pressure to integrate with the rest of the system. The tank’s internal pressure must fall within a specific range (typically 6 to 8 psi) when empty to work properly.
Over time, the tank’s internal pressure may decrease as small amounts of air escape. When this happens, water will enter the tank, but the pressure inside the tank will be too low to send water to the RO faucet. At this point, you’ll notice little or no water coming out of your faucet.
To fix this issue you’ll need to repressurize the storage tank. To do this complete the following:
- Turn off the feed water valve under the sink.
- Open the faucet and allow any water inside to drain (if possible).
- Now, turn off the tank valve, disconnect the tank from the system, and take it outdoors or somewhere else with sufficient drainage.
- Open the tank valve, and allow water to flow out. Then connect a bicycle pump or air compressor to the tank’s pressure valve and pump out the rest of the water.
- Attach a tire pressure gauge to the pressure valve on the tank to get a pressure reading.
- Then, add pressure to the tank using a bike pump or air compressor as needed. If using an air compressor go slowly and be careful not to overinflate.
- Check the pressure as you go and stop when you reach the desired pressure level.
While less common, if your tank pressure is too high, water flowing from the membrane won’t be able to enter the tank. This will cause an excessive amount of water to flow down your drain line.
To fix this issue, you’ll want to perform the steps outlined above, but instead of adding pressure to the tank, depress the valve to release pressure until you reach the desired level.
Ruptured Tank Bladder
RO storage tanks feature internal rubber bladders to regulate their internal pressure. Over time and repeated use, these bladders can eventually rupture.
When this happens, the tank will continue to fill with water, but it won’t be able to send sufficient water to the RO faucet.
To test whether you have a ruptured tank bladder, you’ll need to repressurize your tank using the steps outlined above. After repressurizing, connect the tank to the system, allow the tank to fill, and then open the faucet. If the tank can only send a glass or two of water to the faucet before slowing down to a trickle, then your bladder is ruptured.
Unfortunately, there is no way to replace a ruptured tank bladder. You’ll need to replace the entire tank.
Empty Tank (High Water Usage)
Another potential cause for no water coming from your system is higher than normal water usage. Once an RO storage tank is emptied, it takes several hours for it to completely refill. If you don’t allow sufficient time for the tank to refill, then you’ll only have a trickle of water coming from your faucet.
This is completely normal for tanked RO systems and isn’t a cause for concern. If you’ve used an unusually large amount of water, there’s a good chance your tank is simply empty and you need to wait for it to refill.
If you find yourself running into this issue regularly, you might want to upgrade to a larger storage tank or add a second storage tank to your system.
You Need to Wait
RO systems are notoriously slow at filtering water, which is why they incorporate storage tanks to keep a reserve of water on hand. If you’ve just installed your RO system or performed certain maintenance tasks, you’ll need to wait for the system to process water and the tank to refill before using the faucet.
Clogged Filters/Reverse Osmosis Membrane
Reverse osmosis filters and membranes must be changed periodically in order to keep them functioning properly. If they’re not changed, then they will eventually clog up – leading to a sluggish or no water flow.
If you suspect one of your filters or membrane is clogged, simply remove that filter or membrane, and run the system with the filter element removed. If the system starts running correctly, then you’ve found the source of your problem.
To fix this issue, simply replace the clogged filter element with a new one. To prevent this from occurring in the future, be sure to change your filters and membrane according to the manufacturer’s recommendations.
Low or Fluctuating Feed Water Pressure
RO systems require a minimum feed water pressure to function correctly (generally 40 psi). If your pressure falls below the minimum threshold, the membrane will not work.
To fix this issue, you’ll need to install a booster pump to increase your feed water pressure.
Bad Flow Restrictor
The flow restrictor is used to limit the flow of wastewater down the drain line. This is needed to maintain pressure inside the RO membrane to keep it functioning correctly.
If your flow restrictor is broken or malfunctioning, it won’t limit the flow down the drain line and the RO membrane won’t have enough pressure to operate. As a result, water will simply flow down the drain line, and little to no water will make it through the membrane.
A bad flow restrictor must be replaced to get the system running again. The process will vary depending on your system, so consult your system’s manual or contact the manufacturer for details.
Bad ASO Valve
The ASO (Auto Shutoff) valve is the valve that triggers the system to start and stop filtering water when the storage tank empties/fills. If this valve malfunctions, there are a number of possible issues that can result.
The ASO valve can get stuck in the ‘closed’ position, which will prevent any water from entering the system. This can be fixed by disconnecting the ASO valve to release pressure and then reconnecting it.
If the valve is broken, then your system will not shut off when the storage tank is full, which will lead to constant operation and a lot of wasted water. In this case, you’ll need to remove the broken ASO valve and replace it with a new one.
Kinked Tubing
Kinks or bends in tubing lines can cause blockages throughout the system. This can lead your reverse osmosis system to stop producing water.
Generally, kinks and bends are caused by sections of tubing that are longer than necessary.
If you suspect this might be the cause of your problem, take a close look at the tubing connections running between your system’s stages. If you spot a kink or a bend in the tubing, turn off the feed water valve, remove that section of tubing, and either shorten it or replace it with a shorter tubing section.
Further Reading:
Poor Feed Water Quality
If your feed water is particularly low quality, it will clog your filter elements significantly faster than normal. If your filter elements consistently clog faster than normal, there’s a good chance you’re dealing with poor-quality feed water.
To determine if your feed water is the problem, the best thing to do is have your water professionally tested. This will give you precise results for the contaminants in your water as well as their quantities.
To deal with this issue, you may need to install additional pre-filtration to your system. Certain contaminants such as iron or water hardness can be tough on RO systems and should be removed before water can reach the RO membrane.
Source Water Is Too Cold
Very cold water can slow down the filtration process significantly. This isn’t a particularly common issue, as most homes are well-insulated enough to avoid this.
If your source water is too cold, you can install a booster pump to help compensate for this issue. Alternatively, you can add some form of heating or insulation to your home’s main water supply.
How Does a Reverse Osmosis System Work?
Reverse osmosis systems use water pressure to force-feed water through an ultra-fine membrane. This membrane will remove any contaminant down to just .0001 microns in size. As a result, RO systems are capable of removing a wide array of contaminant particles including microbial contaminants, heavy metals, salts, and much more.
While RO membranes are incredibly effective filters, they are not capable of filtering everything. In particular, sediment particles and chlorine/chloramine will damage and pre-maturely clog RO membranes. As a result, RO systems typically feature sediment and activated carbon pre-filters to remove these contaminants before they can reach the membrane.
Most RO systems also feature a final carbon post-filter to ‘polish’ the water’s taste and remove any lingering contaminants.
How RO Storage Tanks Work
As reverse osmosis filtration is a slow process, RO storage tanks are used to keep a reserve of filtered water ready to use at all times.
These tanks are pressurized to work with the rest of the RO system. They contain both an air and water chamber separated by a rubber bladder. As water flows into the tank, the water chamber fills, compressing the air chamber and increasing the pressure in the tank.
This pressure is what allows water to flow from the tank to the RO faucet without the need for a pump or motor. It also activates the ASO valve to trigger the system to start/stop filtering water when the tank is emptied/filled.
If you have any questions about your RO system not producing water please don’t hesitate to leave a comment below!
About the Author Alexandra Uta
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