The phrase refers to instructions or a set of guidelines for preparing a potable beverage using water sourced from a lake. Such instructions may include methods of purification, filtration, or the addition of ingredients to improve taste or safety. An example would be a step-by-step guide detailing how to filter water from a specific lake and then add electrolytes for rehydration purposes.
The availability of a safe preparation method can be critically important in survival situations, remote outdoor activities, or areas where access to treated water is limited. Historically, communities near lakes relied on this water source, employing various techniques to render it suitable for consumption. Properly preparing such a drink can provide hydration and essential minerals but carries inherent risks if appropriate purification measures are not followed.