Reverse Osmosis Systems Troubleshooting Guide


So you’ve made that hefty investment and purchased a reverse osmosis water filter. But a few moments after you install it, you realize it’s not a walk in the park. Your reverse osmosis drains all the time, or you experience leaks, slow water flows, damaged tubing, or even bad tastes. 

Before you think that you just wasted your resources, we’re here to show you how you can quickly fix these problems. But before that, let’s first define what reverse osmosis is, and how RO systems work.

What Is Reverse Osmosis?

Reverse osmosis is the process where water containing sediments, dissolved gases, and other elements is pushed through a semipermeable membrane. Since this process goes against the natural osmosis process, you need some amount of pressure.

The actual osmosis system involves water from a lower concentrated zone moving to the higher concentrated region through the semipermeable membrane. The resulting reverse osmosis water is safe for drinking. It’s like creating bottled water at home. Below are some of the concepts you need to know to understand how a reverse osmosis system works.

Terms You Need To Know

  • Water quality: Part per million (ppm) is the unit measuring it. Another unit is the milligram per liter (mg/L). Conductivity meter measures total dissolved solids present in any water in the RO system.
  • Total dissolved solids (TDS): These are particles suspended in water.
  • Source water: This is any water supplied to the RO System.
  • Percent rejection: This is the percentage of total dissolved solids removed from source water.
  • Percent recovery: This is the percentage of clean or particle-free water after passing through a reverse osmosis water filter.
  • Product water: This is water obtained after the process of reverse osmosis.
  • Wastewater: This is the water that goes through the drain after purification.
  • Silt density index: This is a measure of the fouling of reverse osmosis systems by suspended elements in the water. It measures the time it will take for a predefined amount of water to be filtered by a 0.45-micrometer standard filter.

Important Components You Need To Know

  • Membrane – This is the tool that helps remove the unwanted elements in the water. When there is enough pressure, the more concentrated water is pushed through the membrane. The water pressure from your feed source and the temperature of the water, determine the pressure. Also, if you live in an area with low water feed pressures, you can always get a reverse osmosis system with a boost pump. 
  • Filters – There are two types of filters in a reverse osmosis system, pre-filters and post-filters. There are the pre-filters that remove chlorine and sediments. It’s important to remove chlorine before it reaches the membrane since it may destroy it. Post-filters, on the other hand, remove any elements that managed to go through the previous stages.
  • Flow restrictor – A flow restrictor blocks the flow of water to maintain the optimum pressure for the membrane. It also helps keep the water efficiency ratio by minimizing the water that goes to the drain.
  • Check valve – This is the valve that controls the reverse osmosis water. It ensures that the tank has enough pressure and water and prevents backflow that could damage the membrane.
  • Automatic Shut-off valve – This valve controls the feed water. When the tank is at least 2/3 full, it closes the water flow. A combination of this ASO valve and the flow restrictor regulates the water flow and ensures that your RO system lasts longer. 
  • Drain Saddle – This is the connector that allows water from the RO system to drain. It’s attached to the kitchen sink’s drain line.
  • Feed Pressure – This is the pressure of the water going into the RO system. TDS, temperature, and pressure have significant effects on the performance of a Reverse Osmosis System.
  • Air gap – This is the break between the feed water supply and the drain water. Its role is to prevent the backflow of drain water into the RO system.

Reverse Osmosis: Issues and Solutions

Below are some of the common RO system problems and how to fix them:

Reverse Osmosis: Water Flow Slow or No Water Output

If you’ve connected your reverse osmosis system and there’s no water coming out of the faucet, or the water discharge is too little, you can check the following aspects.

  • Make sure you connected the RO system as instructed. Manufacturers often attach a photograph of how it should look when installed, so use that to cross-check what you missed.
  • Check the tank pressure. The ideal tank pressure should be at least 5 to 7 psi. If it’s too low, then water won’t reach the faucet.
  • Measure the permeate rate and flow rate. 

The Water Flow Won’t Stop

This is the case where reverse osmosis constantly drains. Water flow should stop once the tank is at least 2/3 full. The ASO valve, the flow restrictor, the tank, and the check valve help control the water flow. Below are some of the reasons why water may keep flowing even when the tank is full.

  • The check valve may be “leaking” pressure. If that’s the case, then it may be difficult for the tank to achieve the desired pressure. To test this problem, fill the tank with water, then close the feedwater supply. If water is dripping into the drain, then the check valve has malfunctioned.
  • Another issue may be that the tank is not filling as expected. The membrane could be an issue, so check if it’s clogged, or even replace it.
  • The ASO valve may also be stuck. Disconnect it and discharge all the pressure in the system before reattaching it. 


Leaks are prevalent, especially immediately after installation. If the tube is too long, shorten it to an ideal size. Also, make sure that the pipes are as straight as possible, if they are bent, some of the water may leak through the air gap.

The drain clogs over time, causing leakages. Unclog the drain often to prevent this problem. Also, make sure that the hole you created in the drain aligns perfectly with the drain saddle. If it’s slightly off, then some of the water may leak through the gaps.

Leaks are also common in the filter housings. They often occur if the casings aren’t appropriately attached. For starters, make sure that the tube goes deep into the connectors. If the pipes were damaged on arrival, or you note some cracks later, make sure you replace them as soon as possible.

Reverse Osmosis System Making Noise

The RO system may be making noise and letting out a loud gurgling sound. Air gaps in the system often cause this problem. There could also be objects blocking the water flow in the drain. Also, make sure that the tubes are as straight as possible.

Bad Tastes and Odors

The most common cause of bad tastes and odors in water is the clogging of the filters. When this happens, just replace them. However, some types of water, such as that from the well, may contain some dissolved gases. These gases may go through the membrane. In such a case, the best option is to go for a high-quality RO system that deals with well water and other types of hard water. 

High content of Total dissolved solids

  • Malfunctioning RO water filter or membrane
  • Increase in the amount of Total Dissolved Solids in source water
  • Chlorine has damaged the filter.
  • A case of backflow which causes rupture of casing
  • Malfunctioning O-rings in the filters and membrane housings

If you are facing some of the issues we mentioned, then we suggest you follow these recommendations: 

  • When you have a damaged filter or membrane, you do a thorough cleaning to remove all particles or replace it with a new one.
  • In a scenario where there is reverse flow, which causes a torn filter, consider replacing the check valve.
  • When chlorine damages the filter, you will need to replace it immediately.


And there you have it. These are the most common problems in Reverse Osmosis Systems. As you can see, most of them can be avoided by getting the best reverse osmosis systems. And by best, we mean those with high-quality membranes, high-quality parts, a thorough filtering process, and easier to maintain. 

Some of these issues can be prevented by maintaining the reverse osmosis water filter regularly. If you’re not very handy with such tools, it won’t hurt to hire a plumber to help you install and fix any issues that may arise.

Reverse Osmosis Systems Troubleshooting Guide
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Reverse Osmosis Systems Troubleshooting Guide
Your reverse osmosis system is not working as expected? Click to find out the common of reverse osmosis systems issues and how you can fix them!
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