Does Reverse Osmosis Remove Chlorine?

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Although chlorine is an effective disinfectant, it is harmful to human health if consumed in high dosages and for long. It is added to municipal water to kill bacteria and viruses that could cause sicknesses or diseases.

So, why add chlorine to water when it could cause long-term health complications? The answer is quite simple – chlorine is the most cost-effective solution for water treatment.

And now, to answer the question – Does reverse osmosis remove chlorine from water? The short answer is – yes. Reverse osmosis is one of the most effective methods of removing chlorine from your drinking water.

In fact, reverse osmosis removes up to 98% of chlorine from water.

How Does Reverse Osmosis Remove Chlorine from Water?

Reverse osmosis systems filter contaminants, including chlorine from water by sending it through multiple filtration stages.

Most RO systems feature a sediment pre-filter, an activated carbon filter, an RO membrane and a post-filter.

Although activated carbon filters come in handy when it comes to eliminating chlorine from water, some molecules still bypass this stage.

Next, the water flows through the semi-permeable membrane, which, thanks to its tiny pores, blocks larger chlorine molecules from passing through.

Finally, chlorine and other contaminants are flushed down the drain as pure water flows out through the faucet.

What Are the Health Risks of Drinking Chlorinated Water?

Drinking chlorinated water for a long time can cause the following harmful health effects:

  • Asthma – Chlorinated water can increase asthma symptoms.
  • Food allergies – People exposed to chlorinated water are more likely to develop food allergies.
  • Bladder and rectal cancer – Chlorine and chloramine in water increase bladder and rectal cancer risk.
  • Congenital abnormalitiesA study done in Taiwan found that pregnant women exposed to chlorinated water were more likely to give birth to kids with abnormalities. These deformities include poor brain development and a hole in the heart.
  • Breast cancer – Chlorinated water increases the risk of breast cancer.


How else can you remove chlorine from water?

You can also remove chlorine from your drinking water through distillation. However, the high cost, slow output and high energy consumption make the method less popular.

What level of chlorine is safe to drink?

In low dosages, chlorine is not a dangerous threat to your health. According to the U.S Environmental Protection Agency, municipal water treatment facilities should maintain chlorine levels at no more than 4 mg/L.
Any amount higher than that is considered unsafe for consumption.

Does chlorine damage reverse osmosis filters?

Chlorine damages the RO filters over time. It makes the RO membrane deteriorate, grow larger and become ineffective by letting contaminants pass through.
You, therefore, need to replace the membrane and filters after a period of use (usually 6 to 12 months for filters and 2 years for the RO membrane).

How much chlorine does reverse osmosis remove from drinking water?

Reverse osmosis filters remove up to 98% of drinking water.

What other contaminants does reverse osmosis remove from water?

Reverse osmosis also removes heavy metals from water, total dissolved solids (TDS), bacteria and chemical impurities like herbicides and pesticides.

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Dr. Peter Gleick

Dr. Peter Gleick is an experienced water filtration engineer and technical writer for He is an expert in water purification and filtration, focusing on helping people get clean, safe, and healthy water for domestic use. He has more than 10 years of writing experience and has numerously contributed to leading publications in this field.

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