Water filters primarily remove chlorine through a process called adsorption, especially using carbon filters.
Here's a breakdown of how this works and other methods filters may employ:
Adsorption with Activated Carbon
- The Key Process: Activated carbon filters are the most common and effective at chlorine removal. They use adsorption, where chlorine molecules adhere to the surface of the carbon material. Think of it like chlorine "sticking" to the carbon.
- Activated Carbon's Role: The "activated" part is crucial. It means the carbon has been treated to create a huge surface area within the filter. This vast surface provides countless spots for chlorine to attach.
- Chemical Reaction (Sometimes): While primarily physical adsorption, some carbon filters can also facilitate a chemical reaction where chlorine is converted into chloride, a less harmful substance.
- Types of Carbon Filters:
- Granular Activated Carbon (GAC): Loose granules of activated carbon.
- Carbon Block Filters: Compressed carbon into a solid block, offering finer filtration. These are generally more effective at chlorine removal than GAC filters due to increased contact time and surface area.
Other Chlorine Removal Methods in Water Filters
While carbon filters are the workhorses, other filtration technologies contribute:
- Catalytic Carbon Filters: These filters use carbon that is modified with a catalyst, further enhancing the conversion of chlorine and chloramines (a chlorine-ammonia compound) into less harmful substances.
- Reverse Osmosis (RO): While not primarily designed for chlorine removal, RO systems, often used as whole house filters, can remove a wide range of contaminants, including chlorine. These systems force water through a semi-permeable membrane, physically separating the water molecules from larger contaminants. RO systems usually include a pre-filter with activated carbon to protect the membrane from chlorine damage.
- UV Disinfection: Although UV light does not remove chlorine that's already in the water, it is used to disinfect water. UV disinfection systems can be used in combination with other filtration to provide comprehensive water treatment.
- Neutralization: Some filters neutralize the chlorine using a chemical, though this approach is less common for residential drinking water.
Why Remove Chlorine?
Chlorine is added to municipal water supplies to kill bacteria and viruses, making the water safe to drink. However, it can also:
- Give water an unpleasant taste and odor.
- React with other organic matter to form harmful disinfection byproducts (DBPs) such as trihalomethanes (THMs) and haloacetic acids (HAAs).
- Dry out skin and hair.
Summary
Water filters, especially those using activated carbon, effectively remove chlorine through adsorption. The chlorine molecules adhere to the carbon's surface, improving the taste, odor, and overall quality of the water. Other methods like reverse osmosis and catalytic carbon can also contribute to chlorine reduction.
