How to Flush a Reverse Osmosis System Step by Step
Written by: Alexandra Uta // Last Updated: Jun 1, 2023
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Flushing your reverse osmosis system is one maintenance step that not a whole lot of people do, but it can make sense if you want to extend the lifespan of your RO membrane.
It’s not complicated and doesn’t take a lot of effort either, especially if you have a flush kit.
You just need to figure out the ideal frequency for flushing your reverse osmosis system and of course familiarize yourself with the process…
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Key Takeaways
- You can flush your reverse osmosis system regularly to prevent it from clogging up too fast. Some people recommend doing this every day, while others do it every week
- A flush kit can make the process much easier.
- Without a flush kit, you need to remove the flow restrictor from the drain line and allow the system to run for about 20 minutes.
How to Flush a Reverse Osmosis System Step by Step
How to flush your reverse osmosis system exactly depends on whether you have a flush kit or not. A flush kit can make the process significantly simpler. It’s not strictly required though, and it’s perfectly possible to flush your system without a flush kit. It just requires more work.
How to Flush an RO System with a Flush Kit
If you do have a flush kit, the process to flush your reverse osmosis membrane is very simple. Just follow these steps:
- Align the ball valve with the drain line. The system is now flushing.
- Keep the system running for half an hour or so.
- Once you’re finished, close the ball valve.
How to Flush an RO System without a Flush Kit
It’s still possible to flush a reverse osmosis system without a flush kit, but it takes a bit more work. Here is a brief rundown of the process:
- Close the water supply and open the RO faucet until no more water flows.
- Unhook the drain line from the RO system.
- Remove the flow restrictor from said drain line.
- Attach the drain line back to the reverse osmosis system.
- Keep the system running for half an hour.
- Once the system has been flushed, shut it off.
- Disconnect the drain line.
- Reattach both drain line and flow restrictor.
How Often to Flush a Reverse Osmosis System
It’s difficult to determine a standard frequency for flushing a reverse osmosis system. How often you should do that depends on various factors, which we’ve listed below. You’re going to find a variety of opinions on the matter online, too. For example, some would claim that you should flush the system every day, while others say it’s okay to do it every few weeks or so.
How Long to Flush a Reverse Osmosis System
You don’t need to keep the reverse osmosis system running for too long to flush it effectively. In most cases, 20 minutes should be plenty of time. Once again, this depends on a variety of factors, such as the last time you’ve flushed the membrane, how much fouling there is on it, as well as the overall quality of your water and your usage habits.
Signs That Your RO System Needs Flushing
You should also pay attention to signs that may indicate that your reverse osmosis system needs to be flushed. These include foul odors or tastes in your water, inconsistent pressure, as well as salt permeability reaching 10% or more.
Membrane Performance: Calculating the Salt Rejection Rate
If you have a TDS meter handy, that is a great way to determine how well your membrane is doing. You just need to take two samples of water – one from your regular unfiltered water, and one from the filtered supply – and use a simple formula to calculate your TDS rejection rate:
(unfiltered water TDS – filtered water TDS) / unfiltered water TDS x 100 = rejection rate in percentage
If you get a number below 80-90%, this is a good indicator that you need to flush your reverse osmosis membrane, or even replace it completely.
Further Reading:
Why Flush in the First Place?
Flushing a reverse osmosis membrane can help preserve it for a longer time by removing fouling that accumulates on it. Not everyone does it frequently, but it’s a good way to maintain your system and get the most out of it in the long term.
How to Deep-Clean a Reverse Osmosis System (with Tank)
Deep cleaning reverse osmosis systems is a different process that’s a bit more complicated. It involves turning off your entire water supply, disassembling the pre/post-filtration setup and removing the reverse osmosis membrane from its housing. After that you would scrub the membrane and filter housings with regular dishwater and rinse them thoroughly.
Now you could even add bleach into the first filter housing and let it flow through the entire system (without the filter elements installed) for disinfection. Remember to drain a couple of tanks afterwards.
Cleaning an RO Membrane with Chemicals
It’s also possible to clean your reverse osmosis membrane with chemicals, but that is an even more complicated process. You shouldn’t attempt to do that unless you know exactly what you’re doing.
You need to remove the membrane from its vessel, soak it in chemicals, rinse it, and reassemble the system. It’s important to pay attention to the types of chemicals you’re using and their concentrations.
If you have any thoughts about the question, how to flush an RO system, please don’t hesitate to leave a comment below!
About the Author Alexandra Uta
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