Why Purge Reverse Osmosis For 24 Hours? (Need To Know)

Are you immensely particular about ensuring the purity of the water you drink? Considering that, as per World Health Organization, contaminated water is a source of so many water-borne diseases, it is understandable that many of us don’t mind putting in extra effort to purify our waters.

One way to do so is reverse osmosis (RO), which removes magnesium and calcium from the water and other particles like fluoride, mercury, lead, and chlorine. This method can potentially clean water up to a purity level of 97 percent.

You also need to periodically sanitize the system by purging the water by adding bleach and then letting the water flow out. It is often recommended to perform the purging method for at least a day.

Why purge reverse osmosis for 24 hours? This is because an average reverse osmosis purifier takes 24 hours to release approximately 75 gallons of water (the average amount required to fill a tank). The duration also ensures that all bleach and harmful particles are safely removed.

Why purge reverse osmosis for 24 hours?

To identify why it is important to purge reverse osmosis for 24 hours, we need to take a few steps back and understand the entire cleaning process.

For the reverse osmosis system to remain effective in providing purified water, you must regularly sanitize and clean the water tank. Ideally, you should do this once before implementing the system and after every six months.

The first step of this sanitization process is switching off the water supply and emptying the tank. Then, bleach is added via an eye-dropper. And since we are dealing with drinking water, it is equally important to remove the added bleach.

This is where the prolonged purging comes in. Purging is when water goes through the system by opening faucets and letting the water containing the bleach flow out.

You do this process for 24 hours to ensure that all of the chemicals are removed from the system. After all, you wouldn’t want to drink contaminated water, right? It defeats the purpose of reverse osmosis to begin with!

How long to purge a reverse osmosis system?

There are two ways to answer this question. As you might have gathered from the title of this article, you should purge the system for at least 24 hours. Another metric to look through is the number of times you need to empty the water tank.

There are different types and capacities of water tanks. While it usually takes one tank’s worth of water a day to be emptied, sometimes, the water tanks are smaller, and hence it takes less than a day for them to be emptied.

In this case, the metric is not just emptying the tank once. Instead, you need to do it twice or thrice to purge the reverse osmosis system effectively. This should take a day but can also take longer.

Additionally, another good way to judge how long you must purge the reverse osmosis system is to detect if you could smell the odor of the bleach or not. Only stop when you can’t identify the strong smell of bleach.

Do you have to purge reverse osmosis water filters?

Yes, you need to purge reverse osmosis water filters at least once every six months. However, there are also instances when the various filters need to be replaced rather than cleaned, purged, and reused.

There are different types of filters within an RO system. The first stage has pre-filters through which water must flow first. When it does so, any dirt, sand, and sediments that may exist in the water are filtered out. Every six months, this filter needs to be replaced. So, whenever you purge the system, this pre-filter has to go!

The second stage has a carbon filter that removes odors, chlorine, and other chemicals. This filter is immensely important for the RO membrane’s longevity and needs to be changed after six months.

Now comes the real reverse osmosis phase. This is where water passes through a membrane at high pressure so that all contaminants stay at one side and pure water is released to the other. Compared to other filters that need to be changed quite frequently, a membrane can last for over two years under optimum conditions.

In the fourth and final stage, another carbon filter is present that removes any lingering odor and taste from the water. Like the previous carbon filter, this one also has to be changed in six months.

Do you need to purge a new reverse osmosis tank?

Why Purge Reverse Osmosis For 24 Hours

You might have noticed that I have so far stressed the importance of purging and cleaning a used reverse osmosis tank. But what about when you freshly install the system? Can you begin using it from the get-go, or should you purge it first?

You should sanitize and purge the system first.

Think of it this way. All new equipment, albeit properly packed and delivered, tends to go through quite a long process before reaching your doorsteps. That’s a lot of potential germs that might be lingering in them. This is true for reverse osmosis systems as well.

Here, sanitizing the system by adding bleach and then purging it properly is even more important than sanitizing some of the other equipment you may use.

This is because a reverse osmosis system is meant to purify your drinking water. The last thing you would want is to drink contaminated water from a system meant to do the opposite, right?

So, when you get a new reverse osmosis tank, purge it first. You also need to invest at least 24 hours in the purging process. Just because something is new doesn’t mean a lesser quantity of bleach is required or there aren’t other contaminants that need to be flushed out!

Let the purge take its due time.

How to purge a reverse osmosis system?

Is this your first time trying to purge? Now that you know why purge reverse osmosis for 24 hours, let’s see how you can perform the process. Remember, there is more to purging than merely opening faucets and letting all the water flow. As discussed above, there are steps that need to be taken before this.

Why Purge Reverse Osmosis For 24 Hours?

Here are all the required steps for purging the RO system.

  • Turn off the water supply line so that no new water enters the reverse osmosis stem.
  • Drain all existing water from the system by opening its faucet. This will also take considerable time to be completely devoid of water.
  • From the feed water, remove the pre-filter housing and clean it. You can choose to either replace the filter or reinstall it. The same also holds for reverse osmosis membrane.
  • Apart from the pre-filter enclosure, reconnect the system.
  • Add a disinfectant pack or three tablespoons of bleach to the pre-filter housing. Proceed by connecting the filter with the system.
  • Switch on the water supply line so that the bleach water can fill up the reverse osmosis system in an effort to sanitize it. Ensure that there are no leaks.
  • The water should fill to the brim of the system. This should ideally take 10 minutes in the standard water pressure. It can take more time if the pressure of the water is low.
  • Open the faucet of the reverse osmosis system. First, air will escape, followed by water.
  • When water starts flowing, turn off the faucet. Leave it be for 30 minutes for the sanitization process to properly occur.
  • Then, begin rinsing the system off the bleach by turning on the faucet and letting water flow for five minutes.
  • Close the water tap and turn on the RO faucet. Now, you should wait for the entire tank to get empty. Repeat this multiple times for a day.
  • Replace the filters and membrane that were previously removed during this stage.
  • Check for leaks or bleach smell before letting the storage tank fill up again for use.

With these seemingly lengthy but simple steps, you will be able to successfully sanitize and purge the reverse osmosis system.

Why Purge Reverse Osmosis For 24 Hours?

Conclusion | Why Purge Reverse Osmosis For 24 Hours?

All in all, why purge reverse osmosis for 24 hours? You need to do so to retain the effectiveness of the reverse osmosis system. The purging process is a key aspect of the sanitization of the system. If you don’t do this step properly, you might end up with water with bleach in it.

As we are dealing with drinking water, this misstep is not an option. So, while the process is quite lengthy, given the purging lasts a day, do the needful once every six months so that you and your family can continue to enjoy pure water.

If there are any other questions that you have about the purge reverse osmosis system, comment below. As a user of the filter myself, I have accumulated a lot of insights about it in the past few years!


This is my blog about the ways and solutions that can help you improve your health by taking more value from drinking water. As improving health means a lot to me, I decided to create the Water On Top project with the purpose to reveal the benefits of water, the finest products to take our daily water to another level, and much more great stuff about water that I believe is on top of our nutrition.

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