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Why Purge Reverse Osmosis for 24 Hours?

Scott Winfield
Written by Scott Winfield
Last Updated on

A reverse osmosis system needs frequent maintenance to function properly. Typical maintenance practice involves changing the filters every 6 – 12 months and occasionally cleaning the RO membrane.

Sanitization is another common maintenance practice to prevent recontamination. It involves cleaning the entire RO system with a sanitizing agent like bleach, then purging the system to remove bleach residue.

The time needed to purge the system depends on the sanitizing agent used, but on average, it takes about 5 – 20 minutes for purging to complete. Some extremely rare cases may take up to 24 hours.

So, why purge reverse osmosis for 24 hours? Purging for 24hours is needed to completely get rid of the bleach residue after sanitizing the RO system, especially if the system has a small water outlet.

How to Purge a Reverse Osmosis System

Purging a reverse osmosis system is very simple. After sanitization, you only need to open a particular faucet and let the water run through it for a couple of minutes (or longer if it hasn’t been sanitized in a long while). It’s normal for the water flow to be merely a trickle at this point, since the storage tank gets emptied during the sanitization process.

After letting the faucet run for a while, close it and wait another 2-3 hours for the storage tank to refill. A standard RO tank has a capacity of 2.8 gallons, so if your particular tank is larger, you might need to wait longer. Once your storage tank is full, you can use the RO system.

If you notice bleach smell after purging the system, it’s likely that you’ll need to let the water run even longer. Sanitizing agents such as bleach can be extremely dangerous if consumed, so it’s important to properly flush the system after sanitization.

Maintaining a reverse osmosis system

How Frequent Should You Purge?

We advise to purge the system upon every filter replacement, which should be done at least once a year. New systems should also be properly sanitized and purged upon the first installation to purge dirt and debris contamination during the installation process.


While committing to using a reverse osmosis system might seem daunting, the benefits far outweigh the drawbacks. However, frequent maintenance is needed to keep the system functioning properly. That’s why it is important that you’re patient, even with something as simple as purging the system for 24 hours if necessary.

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Scott Winfield
Scott Winfield
My name is Scott Winfield and researching and writing about water filters and other strategies to purify water has become my full time passion in recent years. I'm glad that you found our site and you can look forward to authoritative and well researched content here to help you get the best in water.
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