Which of the following is NOT a rule covering water discipline?

The choice indicating "Do not share water" as the option that is NOT a rule covering water discipline is accurate because water-sharing practices are typically addressed within the overall context of limits on personal water use and secure communications during operations. The other options emphasize critical aspects of water safety and conservation in military settings.

Drinking only from approved sources is fundamental to preventing waterborne diseases, ensuring that personnel consume water that has been tested and deemed safe. Conserve water underscores the importance of managing resources effectively, especially in field operations where water may be limited. Additionally, the directive to not contaminate water sources is essential to maintaining the integrity of available water supplies and preventing outbreaks of illness that can arise from polluted water.

Thus, while sharing water may not be directly prohibited under the formal rules of water discipline, the focus remains on minimizing risk through careful management and use of water resources rather than the social behavior of sharing.