Which practice is NOT recommended for obtaining potable water in the field when supplies are limited?

• A. Use commercially treated water or boil water for at least 1 minute; use water purification tablets or filters; avoid drinking from unknown sources.
• B. Drink from streams that look clean and clear.
• C. Collect rainwater in unclean containers.
• D. Drink seawater if freshwater is unavailable.

Answer: (B)

The key idea is that water safety in the field depends on treating or using clean sources, not on how water looks. Clear or pristine-looking water can still harbor invisible pathogens and contaminants, so it must be treated before drinking.

Drinking from streams that look clean is not recommended because appearance isn’t a reliable indicator of safety. Microorganisms such as Giardia, Cryptosporidium, and various bacteria can live in seemingly clear water, and they won’t be removed just by looking at the water.

In contrast, using water that’s been commercially treated or boiled for at least a minute, or purified with tablets or filters, is the reliable way to reduce risk. Collecting rainwater is acceptable if the containers are clean, and seawater should never be consumed as a source of potable water because its high salt content can lead to dehydration and serious health problems.