Reverse osmosis (RO) is one of the best filtration methods for removing chlorine from drinking water. In fact, RO systems can often remove over 95% of chlorine, and some models can even remove up to 99%.
But, how do they do this?
How Does Reverse Osmosis Filters Remove Chlorine?
So, we’ve established that RO filters are one of the best ways to remove chlorine from drinking water.
It’s because RO systems include a semi-permeable membrane that’s filled with tiny pores. The size of the pores varies between models but is typically in the range of 0.0001 to 0.001 microns.
During the RO process, water is forced through the semi-permeable membrane, and contaminants like chlorine are trapped in the small pores.
Water molecules, which have a smaller size, can pass through the membrane, which leaves you with purified water at the end of the process. The leftover contaminated water is then flushed out of the system into the drain.
Why Would You Want to Remove Chlorine from Your Water?
OK, now you know how an RO system removes chlorine from water—but why is this a good thing? There are two main benefits to removing chlorine from your home’s water supply:
- Odor and taste: Chlorine is useful as a disinfectant in municipal water supplies. However, when there are high levels of chlorine in your water, you may notice an unpleasant taste and odor. By using an RO system to remove the chlorine, you can improve the palatability of your drinking water.
- Dry skin and hair: Although it hasn’t been proven, some people report that chlorine irritates their skin and causes their hair to dry out. So, bathing in water that contains high levels of chlorine may not be ideal. If you experience these issues, it’s best to install an RO filter.
If the chlorine in your home’s water supply isn’t causing any of the above issues, then you probably don’t need to worry about removing it.
Still, RO filters are also highly effective at removing other contaminants like bacteria, viruses, protozoa, heavy metals, fluoride, and pesticides. This makes them worth installing even if chlorine isn’t a big concern for you.
Does Chlorine Damage RO Filters?
Chlorine can damage reverse osmosis filters over time. Usually, it won’t damage the entire system, but it will likely hydrolyze and affect the semi-permeable membrane and filters. When this happens, the openings in the membrane will deteriorate, growing larger and letting in more contaminants.
Chlorine can also damage other parts of the filter besides the membrane. The rubber parts of the filter, like the seals and o-rings, are affected by the presence of chlorine.
Chlorine is corrosive, but the speed at which corrosion occurs depends on the amount of chlorine in the water. Water significantly contaminated with chlorine will affect an RO filter much quicker than water that’s only lightly contaminated.
As the membrane degrades, it becomes less effective at removing chlorine and other water contaminants.
What Are The Signs of Chlorine Damage in an RO Membrane?
As RO membranes remove many different contaminants, it can be hard to tell if chlorine is the specific cause of degradation. Usually, an RO membrane degrades over time because of several different factors.
Still, there are some signs you can look out for that suggest the filter has been degraded and needs to be replaced, such as:
- Poor water quality: If the membrane is degraded, it might be struggling to remove chlorine and other contaminants from your water supply. This can result in poor-quality water with an unpleasant taste and odor.
- Reduced water flow: When membranes degrade, they start to clog and allow less water to pass through. This results in decreased water flow within the home.
- Increased Total Dissolved Solids (TDS): If you test your water and realize there are more TDS present than usual, it means the membrane is probably degraded.
If you notice any of these signs of degradation, it’s time to replace the membrane in your RO system. Generally, RO membranes need to be replaced around once every 2 to 5 years. Yet, this can vary widely depending on factors like water usage, water quality, membrane quality, and pre-filtration.
If you’re unsure how often to replace your system’s membrane, consult the manufacturer’s instructions.
How to Prevent Chlorine Damage in RO Systems
Chlorine damage is irreversible, but, fortunately, there are several ways you can prevent it or at least reduce its impact on your RO system. Some of these methods include:
- Pre-treatment: Installing an activated carbon pre-filter is a good way to remove chlorine from water before it reaches the RO membrane. Activated carbon removes the excess chlorine, transforming it through a chemical reaction into chloride, a non-corrosive and non-oxidizing substance, which effectively protects the RO membrane.
- Installing a water softener: Another way of reducing the effect of chlorine over time is through a water softener. A softener can help protect the reverse osmosis system by exchanging damaging ions for non-damaging ions before the water reaches the RO membrane.
