Which treatment method is effective for reducing biological contaminants in drinking water?

Chlorination is regarded as an effective method for reducing biological contaminants in drinking water because it involves the addition of chlorine to the water, which acts as a powerful disinfectant. Chlorine is capable of killing a wide range of microorganisms, including bacteria, viruses, and protozoa, thereby improving the overall microbiological quality of the water. This method not only disinfects the water but also helps in maintaining a residual disinfectant level in the distribution system, further ensuring that any potential recontamination does not occur.

Other methods, while useful in different contexts, may not provide the same level of efficacy against biological contaminants. For example, filtration with gravel primarily serves to remove larger particles and sediment but may not effectively eliminate smaller pathogens. Heat treatment can be effective for destroying bacteria and viruses but may not be practical for large-scale or continuous water supply systems. Carbon adsorption is excellent for removing organic compounds and certain chemicals but does not effectively kill biological organisms. Thus, chlorination stands out as the preferred choice for biological contamination reduction in drinking water systems.