9 reasons why there is slow or no flow at your RO water filter’s faucet?

Nowadays, having a water filter at your home or office is a common scenario. Most popular among these filters is the 

Many of us already have one of our own at home. As a result, from time to time, we stumble upon one or two issues.

Being a highly technical product, some of us don’t seem to bother about the problem and happily hand over it to the local plumbing personnel.  

But, that’s not always the case. The problems are sometimes not that difficult. And, also the solution is even simpler. 

One of the common problems that we regularly face in Reverse Osmosis filters is that even after opening the faucet, there is a very slow flow. Even in some cases, there is no flow at all.

Today, in this article, we would be tackling this issue and how to solve it ourselves. So, if this one bothers you as well, take a look. You’ll surely find the solution.

How does reverse osmosis filters work?

To find out why the problem occurs, you need to have a basic understanding of the components of a regular reverse osmosis water filter.

So, let’s see what stays inside a RO water purifier. The basic components of a RO filter are as follows-

• Pre-filter
• Reverse osmosis membrane
• Post-filter
• Water storage tank
• RO faucet
• Tubes and connects

Now, let’s get a basic overview of where the water storage tank fits in all these.

The tap water enters through the pre-filter. After initial screening, the water loses sediment particles and some other pollutants.

Then, the water enters the reverse osmosis membrane where it gets rid of most of the dissolved particles from the water.

This is where the storage tank comes in. You see, we don’t always drink from the RO filter. Most of the time, it remains idle.

Although it might seem idle, it continues to work until you shut it off. During this time, it purifies water and stores it into the tank.

Then, when we open the faucet, the stored water from the tank enters through the post filter and comes into the open.

So, in short, the tap water passes through the pre-filter and the reverse osmosis membrane. Then, it gets stored in the tank. And, as soon as you open the faucet, the water passes through the post-filter and gets poured into the glass.

Now that you have a basic concept of how a RO water filter works, you can realize the storage tank is a very crucial part of the RO purifier.

How does the RO storage tank work?

Now, let’s get a basic overview of how the storage tank works. The RO reserve tank uses a mechanical process of hydro-pneumatic pressure. Let’s explain.

There are two compartments in the tank. One holds air while the other one stores the purified water. 

There is a diaphragm that stays in between these two compartments. As the water from the RO membrane continues to enter the tank, the water chamber gets inflated.

As the total volume of the tank remains the same, this puts more pressure on the air chamber. This pressure is what sends the water through the faucet when we open it.

So, in short, the purified water from the RO membrane gets stored in the tank. As a result, the water chamber fills up gradually. The more water, the more pressure it puts on the air chamber.

This pressure translates into mechanical energy. And, as soon as we open the faucet, this energy propels water to come out of the faucet impeding gravity to some extent.

So, you see, the whole process depends on a delicate balance of water pressure coming from the RO chamber and the pressure from the air chamber.

On this note, there is a limit as to how much water the tank can hold at a time. If the limit is exceeded, the tank valve automatically shuts off until you open the faucet and pour some water.

Why is there slow or no flow at my RO faucet?

One of the common problems that you might face in the case of RO water filters is no water at the faucet.

That means you open the faucet, but the water is not coming out. This one is a very familiar problem. Another similar problem is a very slow flow of water at the dispenser.

Now, let’s find out the reasons why this might happen. The most common causes are as follows- 

• The system is just starting up.
• The water supply is off.
• The tank valve is off.
• Incoming water pressure at the RO membrane is very low.
• Air pressure is very low at the storage tank.
• There are crimps at the output tubings.
• The pre-filters have been clogged with sediment.
• The reverse osmosis membrane has been blocked.
• The system has not been installed properly.

The system is just starting up

The first reason is pretty straightforward. You have your water filter installed very recently at your home. Soon, after that, there will be no flow at the RO faucet.

What’s the solution?

The RO water filters require a certain amount of time to work out. With enough pressure, the water will slowly fill up the tank and then, you can get purified water at the faucet.

So, when the system is just starting up, it will take some time to fill up the tank. There’s no getting rid of this.

Water supply is off

Another reason that might cause no flow at the RO faucet is that you haven’t turned on the water supply.

Again, this is very common for newly connected RO systems.

What’s the solution?

The solution is pretty simple. Just check whether the water supply is off or not. If it is off, turn it on and check the position of the feedwater valve. You need to make sure that is on as well.

The tank valve is off

A common reason for no flow in freshly installed RO water purifiers is that the tank valve has been in the off position.

What’s the solution?

Like the previous problems, the solution is pretty simple as well. Just check if the tank valve is in the right position. If it isn’t, just turn the tank valve on.

Incoming water pressure at the RO membrane is very low

A technical reason that might cause no or low flow at the RO faucet is there is insufficient pressure incoming at the RO membrane.

You already know that most RO membranes out there require at least 45 PSI of pressure to purify water. If the pressure falls below that it will purify less and less amount of water each time.

As the amount of product water at the end of the membrane is very low, the tank will not fill up sufficiently. As a result, there will be a slow flow at the RO faucet.

Therefore, the input water pressure at the Reverse osmosis membrane should be higher than 45 PSI so that there is a sufficient flow of purified water at the output.

What’s the solution?

To solve this problem, you need to use a pressure gauge to check whether the input water pressure at the RO membrane is sufficient or not.

If the pressure falls below 45 PSI (pound per square inch), you need to use a booster pump or a permeate pump. The booster pump will increase the input water pressure at the RO membrane.

On the other hand, the permeate pump will improve the pressure at the output of the RO membrane so that the flow rate to the tank is high enough to fill up properly.

Air pressure is very low at the storage tank

Another technical reason that might cause slow flow at the faucet is the lack of pressure inside the tank.

We discussed previously how the pneumatic pressure inside the tank propels water to the faucet. The air chamber inside the tank is pre-charged when you install it first.

But, due to continuous usage, the chamber continues to lose the pre-charged pressure. As a result, it cannot create enough flow of purified water at the faucet.

What’s the solution?

To solve this problem, you first have to check the pressure inside the tank. In general, the air chamber will exert a pressure of about 5-10 PSI inside the tank.

Therefore, you should use a pressure gauge to find out whether the pressure inside the tank has fallen below the required range.

If the pressure is low, you need to pre-charge the storage tank. To do that, you need to drain all the water from the tank.

Then, you should remove the air valve cap. Now, you should add air to adjust the air pressure inside the chamber.

After the pressure is adjusted, you should release the air valve. In this fashion, you can adjust the air pressure inside the storage tank. This will help improve the water flow at the faucet.

There are crimps at the output tubings

In many cases, crimps in the tubings cause a lack of output water flow at the faucet. These crimps can significantly impede the water flow and as a result, you don’t get water fast.

What’s the solution?

The solution is simple. You need to make sure the tubings are straight at all times. 

The conventional RO water filters use a variety of tubes and all of those are necessary for proper function.

Crimps in one of those might obstruct the water flow and therefore, all the tubes should be checked to ensure that there are no such barriers at all.

If there are crimps, you need to straighten those as soon as possible.

The pre-filters have been clogged with sediment

Another reason behind the slow flow at the reverse osmosis faucet is that the pre-filters have become blocked with sediment or pollutants.

There are some pre-filters before the RO chamber to keep out the dust particles. Over time, they get blocked by sand and silt particles.

As a result, the input water pressure falls sharply at the RO membrane. This, in turn, causes slow flow at the tank and subsequent slow flow at the dispenser.

What’s the solution?

The pre-sediment and activated carbon filters have a certain lifespan. Due to continuous usage, they get blocked by sediment.

In most cases, the pre-filters can last from 6 months to 1 year. After that, you need to replace those to keep the system functional.

If you’re looking for the timeline to replace the cartridges of your water filter, you should check out our post here.

The reverse osmosis membrane has been blocked

Another seldom reason for the lack of water flow at the faucet is that the RO membrane has gotten older and jammed over time.

As the reverse osmosis membrane purifies the water if it gets jammed by the pollutant, the water flow at the input and output will fall proportionately.

For this reason, there may be a dull flow at the dispenser.

What’s the solution?

The solution to the problem is you have to replace the semipermeable membrane.

Like the pre-filters, the RO membrane has its life span. In most conventional RO filters, they can last up to 2 years.

After this, the RO membrane continues to lose its effectiveness and gets clogged by pollutants. Eventually, this causes water pressure to go down all over the system.

Therefore, you should replace the RO membrane as part of regular maintenance. You should check out our post here to get the necessary timeline.

The system has not been installed properly

Last but not least, poor installation of the water filter paves the way for sluggish flow at the dispenser. 

If the tubings are not connected properly, it will disrupt the water flow throughout the system.

What’s the solution?

The solution is straightforward. You should follow the guidelines from the installation manual or take professional support for this purpose.

Most reverse osmosis water filters, these days, come with easy to follow DIY installation manuals. So, you need to follow those to make sure you’ve installed the system properly.

At a glance: why there is slow or no flow at my RO faucet and how to solve that?

We’ve compiled a table showing you the nine reasons behind sluggish flow at the RO faucet. Take a look.

Conclusion

Throughout this article, we tried to answer one of the frequently faced problems with reverse osmosis (RO) water filters.

 We discussed why there might be a sluggish flow of water at the faucet and how to get around those.

If you’re facing this problem at your home water filter, we hope you’ve found your solution in this article.

If you still haven’t found your intended solution, you can let us know in the comment section.

Also, you should visit our blog page here to get more informative posts like this. Don’t forget to share it with your friends. Cheers!!!