Reverse osmosis water filter troubleshooting- what are the problems in RO water filters?- A complete guide

Reverse Osmosis (RO) Water Filter Troubleshooting- A complete guide

For most of us, water filters have become an essential household commodity. As a result, there are so many variants you will find in the market.

But, the one which is currently on the top is the reverse osmosis water filter. Due to its high accuracy and reasonable cost, it is quickly becoming the face of water filters all over.

As the uses of RO filters are increasing, it’s only a matter of time till you get one of your own. But, one thing you need to keep in mind is that these filters can also malfunction.

  • In this article, we’ll show you the common problems that can occur in a reverse osmosis water filter system. We’ll be discussing how to solve those as well. So, let’s begin.

What is a reverse osmosis water filter?

A filter that uses reverse osmosis to remove the minuscules particles and purifies water is known as Reverse osmosis or RO water filter.

Reverse osmosis is a process in which water with high-pressure passes through a membrane, and the dissolved pollutants in it get left out. As a result, water becomes pure and clean.

So, you realize, the membrane plays a vital role in the process. The type of membrane that we use here is called the semipermeable membrane, or in short, the RO membrane.

The water pressure is also a crucial factor in the purification process. Most RO purifiers demand at least 30-40 PSI of incoming water pressure to function well.

What are the components of a Reverse Osmosis water filter?

A typical reverse osmosis water purifier doesn’t only contain a RO membrane. But, there are other types of filters as well. Those stay before or after the membrane.

Pre-filters get rid of the insoluble particles from the water, such as dust, rust, debris, sand, and so on. Then, the water enters into the RO membrane.

There it loses the dissolved pollutants as well. Now, the water can gather into a tank or not. Based on that, there are two types of RO purifiers- one with a tank and one with not.

  • In tankless RO water filters, water goes out through the faucet after leaving the RO membrane. There may be a post-filter after the membrane.
  • On the other hand, in other RO purifiers, water stores into the tank. Then, when you open the faucet, water would get out of the tank and come out. In the way, there may be post-filters.

Apart from the filters and tanks, there are a variety of tubes, valves, and other components as well. That’s not all. Water needs to come out of the faucet in the end.

So, you see, the formation of a conventional RO water filter is not simple at all. But, a basic overview of those will help you while troubleshooting a problem.

  • You can visit our post here to get a more in-detail description of all the components of a Reverse osmosis water filter.

Some common problems in Reverse osmosis water purifiers

As we’ve mentioned earlier, a RO purifier contains a variety of components inside. Therefore, if any single one goes rogue, the whole system will follow.

That’s not all. As the filter ages, the chances of malfunction goes high as well. To help you in this purpose, we’ve shortlisted the common problems in reverse osmosis water filters. 

Take a look.

Slow or no flow at your RO faucet

The first one in our list is slow or no flow of water at your RO faucet. The problem mostly appears in filters that have a storage tank. Now, let’s find out why this happens.

Improper installation

One of the common reasons might be improper installation. In most cases, when you’re setting up the device, it might not go well.

  • To get around it, you need to follow the installation manual for your newly bought RO water filter. In general, it stays inside the package.

Valves in the off position

Another reason for a slow flow at the faucet can be the valves are off. There is an inlet valve, a tank valve, and an auto shut off valve in the system.

  • If the valves aren’t in the right positions, the flow rate might go down. That’s why you need to ensure whether the valves are off or not.

Low incoming water pressure

As we’ve discussed before, RO filters require enough water pressure to purify. If the pressure is too low, the filter won’t be able to produce sufficient purified water.

  • To get around the problem, you need to test your incoming tap water pressure. If it is below 30 PSI, you can install a booster pump.

Also, if you’re looking for a RO water filter with a booster pump inside, you should visit our latest article on the best tankless RO water filters.

Lack of regular maintenance

Another major cause of slow flow at the RO faucet is crimping and clogging of the tubes. As a result, the water flow gets disrupted.

  • To solve this, you need to carry out regular maintenance of your filter. Replacing the cartridges from time to time can also help.

If you would like to get a more in-detail article on why there is slow or no flow at the RO faucet, you should visit our recent article here.

Too much reject-water in the RO filter

Another common problem you may run into while using a RO filter is too much water going to the drain. 

You probably know already that RO filters can’t purify the complete input water. A sizable portion of it goes to the drain. You can find out more about it in our recent post here.

Now, let’s find out the reasons for high RO-reject water and how to get around that.

Improper installation

Again, one major cause of high RO-reject water is the lack of proper installation. Unless you connect the auto shut off valve correctly, a sizable portion of water will get wasted.

  • That’s why you need to check whether the ASO valve is on or not. Again, you should check if it connects to the right tubing as well.

Low flow rate at the output of the RO membrane

Another major cause of the high rejection ratio is low flow at the output of the RO chamber. As a result, purified water doesn’t get into the tank fast.

Therefore, most of the input water goes to the drain. One way to reduce this is to use a permeate pump. It will extract energy from the reject-water and serve it to the permeate one.

As a result, more and more water will get purified fast, and your system efficiency will go up. If you would like to know more about permeate pumps, check out our post here.

High TDS in the output water

Reverse osmosis water purifiers are mainly here to reduce dissolved pollutants from the water. Still, sometimes you might see that the output water has a high TDS level.

So, let’s find out how the reasons and how to solve those.

Improper installation

One cause for high TDS at the output water is that you didn’t install the product well. In most cases, it might happen if you forget to put in the cartridges inside the housings.

As a result, the filters or the RO membrane couldn’t get rid of the pollutants from the water. So, you should make sure that all the components are in position.

Input water with high TDS

Another thing that might cause high TDS output water is that the input water also has a very high TDS level.

Most reverse osmosis systems require that the TDS level remains at a certain level. If it exceeds that, the output water will also have a proportionate TDS level.

In this case, you need to contact your water supply personnel. They might provide you a possible solution.

Lack of regular maintenance

If your RO system is old enough, the membrane might lose its functionality. As a result, the water will come out of it, with most of the dissolved solids still in it.

That’s why you need to replace the RO membrane when it expires. You should check out our post here to see how long the membrane and the filters last.

Also, if there is clogging or crimping in the drain line, water will have no other way but to come out through the purified water tubing. Consequently, it will have high TDS.

So, you need to check all the tubing connections from time to time.

Leakage from the RO system

Now, this one is pretty common. That’s because many users run into it much more often than not. The leakages naturally occur in the fittings. So, let’s discuss further.

Leakage from metal fittings

Throughout the whole system, there is only one place where this can happen- at the faucet base. The reason is pretty straightforward.

The faucet base has loosened up. In this case, you need to open the fitting. Then, tighten it using Teflon tape. Make sure it is dry and airtight again.

Leakage from plastic fittings and quick-connect fittings

In a typical RO filter, you will find a variety of connections using tubings and fittings. As a result, if you don’t join them well enough, water will leak.

Most of the filters use quick connect fittings. In these cases, leakages can happen if the tubings don’t enter deep into the fittings. Also, if the tubings aren’t cut square, water might leak.

That’s why you need to cut the tubings straight and along the radius. Make sure it is square. Also, push the tubings deep into the fittings to ensure it connects well.

Leakage from the valve connections

Leakage can also happen at the valve connections. As you’ve seen already, there are a variety of valves in a typical RO system.

These are here to control the direction of water flow throughout the system. Also, that helps maintain water pressure inside.

When you insert the tubings into the valves, there’s a chance of some discrepancies. So, make sure the tubes are deep into the valves.

Also, cut the tubes as much straight as possible. Furthermore, leakages can happen if you don’t drill to the recommended size.

That’s why you should stick to the installation manual when installing your RO water filter.

Cloudy water or air bubbles at the product water

Being an owner of a RO water filter, you might frequently run into this one. The problem is the product water is cloudy. Also, there may be fine air bubbles as well.

Now, let’s find out why those happen.

Fresh system or new filters

The first reason behind air bubbles at the product water is your filter system is pretty new. As a result, it is dry, and water is just starting to flow.

Another reason may be that you’ve replaced the filters very recently. As a result, those will mix some residue Carbon or other elements. Therefore, the water is cloudy.

In any case, you should keep the faucet open. It will flush out the tank slowly. After the flushing, your system will start to produce pure and clean water without any bubbles.


Throughout this article, we tried to show you the various types of problems that we commonly face in Reverse osmosis water filtration systems.

We also showed you ways on how to get around those problems. That’s not all. We also have discussed how regular maintenance can help your RO water filter to last longer.

So, did you find this article helpful enough? Or you still have some questions left. Let us know in the comment section.

Also, if you want to read more informative articles like this, you should visit our blog page here. Finally, don’t forget to share this with your friends and followers. Cheers!!!

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