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Purging a reverse osmosis system refers to the process of running the RO faucet for a long period to eliminate any residue or sanitizing agents in the system.
Purging has three main uses when it comes to RO system maintenance: removing chemicals after sanitizing, removing debris after installation, and priming an RO membrane.
Let’s take a look at each of these use cases in detail, and explain why you may need to purge an RO system for 24 hours.
So, why purge a reverse osmosis system for 24 hours?
Purging an RO system simply refers to opening the RO faucet and allowing the water to flow out for a prolonged period. This will flush any contaminants or debris contained in the system out through the faucet.
But why does this process take a full 24 hours, surely that’s an excessively long time?
The reason for the long purge time is the slow speed at which RO systems filter water. It can take between 2 and 4 hours for a typical under-sink RO system to fill up a single storage tank, so flushing the system can take longer than you think.
Purging the system is generally recommended by manufacturers after you perform certain tasks such as:
Immediately after installing a new reverse osmosis system, the storage tank will still be empty. At this point, you can flush the system by opening the RO faucet and allowing water to slowly drip out for the duration recommended by the manufacturer.
This process will remove any manufacturing debris left in the system and prime the various filter elements. This means it will remove any fine carbon dust left in the carbon filter(s), as well as eliminate any preservatives remaining on the RO membrane.
It probably goes without saying, but you shouldn’t drink any water coming out of the faucet during the purging process.
This 24-hour purging process is recommended by some manufacturers while others recommend filling up the storage tank and then discarding it 1 to 3 times. This process will accomplish the same thing as purging but has the added benefit of priming and flushing out the storage tank – which will remove debris and eliminate any unpleasant tastes or odors.
After replacing an RO membrane, the system will also require purging. This will remove preservatives that manufacturers sometimes use on RO membranes.
Once again, don’t drink any water coming out of the system during the purging process.
Sanitizing an RO system involves adding a small quantity of unscented bleach or another cleaning agent like hydrogen peroxide to the first pre-filter housing with all the system’s filters removed. Then the system is flushed with water to push the cleaning agent through the various filter housings and storage tank.
This process is generally recommended every 6 to 12 months and is necessary to eliminate any microbial contamination that may be growing inside the system or tank.
Of course, while sanitizing your system is important, you don’t want to ingest any of the cleaning chemicals. A thorough purging of the system after sanitizing is the best way to ensure this.
It’s important to note that when you open an RO faucet before the storage tank has filled, most systems will route water directly to the faucet and bypass the tank. This means that during purging, you won’t be flushing the tank unless you allow it to fill fully and then discard it. If you’ve sanitized your system with the storage tank connected, you’ll want to fill and flush out the tank to remove any residual cleaning chemicals.
You’ll know a system is sufficiently purged when you can’t detect any chemical taste or odor in the water.
While some manufacturers recommend purging an RO system for a full 24 hours, this may be overkill for certain applications.
When installing a system for the first time, it’s a good idea to follow the manufacturer’s directions on purging duration. Alternatively, when changing the RO membrane or sanitizing the system, you can simply fill and discard between 1 and 3 tanks. Usually, this will take significantly less time than 24 hours, as a single tank will take between 2 and 4 hours to fill and discard – so you’re looking at somewhere between 6 and 12 hours for the process.
Purging an RO system is very simple. All you need to do is open the RO faucet when the system is in normal operation mode.
If the storage tank is full, water will flow normally until the tank is empty, at which point the water flow will slow down to a trickle. If the tank is empty, the flow will start as a trickle from the beginning.
As mentioned previously, there are three instances where purging an RO system is recommended.
Yes, a new storage reverse osmosis storage tank should be purged before use. This is necessary to remove any debris remaining inside the storage tank from the manufacturing process. It will also help to remove any unpleasant tastes or odors from the rubber bladder inside the tank.
If you have any thoughts about the question, why purge an RO system for 24 hours, please don’t hesitate to leave a comment below!
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