UV Water Purifiers: Can They Remove Chlorine or Chloramines?

When it comes to purifying water, a UV (Ultraviolet) water purifier offers an effective solution for eliminating bacteria, viruses, and other microorganisms. However, it's important to understand its limitations regarding chemical contaminants such as chlorine and chloramines. This article will explore these limitations and the best practices for ensuring your drinking water is safe and clean.

Understanding UV Water Purification

A UV water purifier uses ultraviolet light to kill microorganisms, making it an excellent choice for biological contaminants. The process works by emitting UV light that causes the DNA of microorganisms to mutate, rendering them ineffective and preventing them from reproducing. This makes UV purification an invaluable tool in household and commercial settings.

The Limitation: Chlorine and Chloramines

Despite the effectiveness of UV light in purifying water, it does not remove chemical contaminants such as chlorine and chloramines. Chlorine is one of the most commonly used substances for water treatment due to its powerful oxidizing properties. However, it does not aid in the purification process but instead interferes with it. Let's explore the specifics of this limitation.

Chlorine in Water

When the water supply contains free chlorine, it is often recommended to let the chlorine dissipate before using a UV purifier. This can typically be achieved by allowing the water to sit exposed to air for 24 to 72 hours. This method works well because free chlorine, being unstable, will naturally evaporate. For more immediate solutions, aerating the water can also help dissipate chlorine more quickly.

Chloramines in Water

Some municipal water systems now use chloramines instead of free chlorine for water treatment. Chloramines are more stable and require a different approach for removal. Chemical water conditioners based on sodium metabisulfite or sodium sulfite are commonly used to neutralize chloramines. These conditioners are available from aquarium and pet stores, as well as specialized water treatment suppliers. It's crucial to check the labels to ensure the product you choose effectively neutralizes chloramines.

Practical Applications

To ensure the efficiency of your UV water purifier, it's essential to treat the water first. For instance, if the water contains free chlorine, simply letting the bucket of water sit overnight can reduce the chlorine content. The UV light can then work more effectively without chlorine interference. Similarly, if chloramines are present, using a chemical conditioner before the water passes through the UV light can improve the purification process.

Results from Experimental Studies

Experiments have shown that medium pressure UV light can effectively reduce free chlorine levels. In one study, the UV light reduced free chlorine by 96%, with an average reduction of 98%. While the study did not determine the minimum required portion for a 100% reduction, it highlighted the importance of water quality and the presence of isopropyl alcohol (IPA) from a scrubber, which affected the dechlorination process. Additionally, the study found that the amount of UV required to remove all chlorine increased as the concentration of combined chlorine increased.

Commercial Applications

In commercial settings, UV light can also be used as a safeguard against subsequent contamination. The standard UV sanitation dose applied in measured water systems is 30 μW-sec/cm2. However, if higher levels of combined chlorine are present, a significantly higher UV dose is required for complete removal. This method also provides a high log reduction of microorganisms, enhancing the overall water safety.

Conclusion

While UV water purifiers excel at killing bacteria, viruses, and other microorganisms, they are not equipped to remove chemical contaminants like chlorine and chloramines. To ensure the effectiveness of your UV purifier, it's vital to pre-treat the water before passing it through the purification process. Understanding the limitations and implementing proper pre-treatment methods is crucial for achieving clean, safe drinking water.

Key words: UV water purifier, Chlorine, Chloramine Removal, Water Treatment