Which technology uses sunlight to disinfect water by killing pathogens?

• A. UV Exposure for Water Purification
• B. Reservoirs
• C. Municipal Sewage Disposal
• D. Flint Water Crisis

Answer: (A)

Using ultraviolet light to disinfect water relies on UV radiation damaging the genetic material of microorganisms, which prevents them from replicating and effectively inactivates pathogens. This can be done with UV lamps or, in situations using sunlight, through solar disinfection, where enough UV exposure (often UV-A along with some heat) in clear water reduces the microbial load without adding chemicals. The method is advantageous because it leaves no chemical residues and avoids introducing substances into the water, though its effectiveness depends on water clarity and sufficient exposure time.

The other options don’t involve using light to kill microbes: reservoirs are just storage for water, municipal sewage disposal deals with wastewater management, and the Flint water crisis refers to lead contamination issues rather than a disinfection technology.