What is the simplest field method to render water safe for drinking?

• A. Boiling water
• B. Rely on bottled water only
• C. Use untreated water from natural sources
• D. Use only chemical disinfection

Answer: (A)

Boiling is the simplest and most reliable field method to render water safe for drinking because it universally inactivates a wide range of pathogens with minimal equipment. Heating water to a rolling boil denatures the proteins and damaged membranes of bacteria, viruses, and parasites, so they can no longer cause illness. In practice, bringing water to a rolling boil and maintaining it for about one minute at sea level (and a bit longer at higher elevations) is enough to make most water safe to drink. This approach works even when you don’t know what’s in the water or how clear it is, and it doesn’t depend on precise measurements or special chemicals.

Other options have drawbacks in the field. Bottled water relies on supply lines that might be unreliable in difficult conditions. Untreated water from natural sources contains pathogens that can cause disease unless treated. Chemical disinfection can work, but it requires proper dosing, correct contact time, and can leave taste or odor issues; some organisms are harder to inactivate with chemicals alone. Boiling avoids these complications, offering a straightforward, effective safety step with basic gear.