What water source requires disinfection before it is safe to drink?

Surface water requires disinfection before it is safe to drink because it is more susceptible to contamination from various sources such as agricultural runoff, industrial discharges, and natural pollutants. Surface water bodies, including lakes, rivers, and reservoirs, can harbor bacteria, viruses, and protozoa that pose health risks if ingested.

To ensure the safety of drinking water obtained from surface sources, disinfection processes such as chlorination, UV treatment, or ozonation are employed to eliminate or inactivate harmful microorganisms. This step is crucial for making surface water safe for human consumption, as opposed to groundwater, which often requires less treatment due to its natural filtration through soil layers. Rainwater and desalinated water may also require specific treatments, but the need for disinfection is particularly emphasized for surface water due to its vulnerability to contamination.