On a fundamental, biological level, water is the most critical, ingestible resource for survival of most any organism, including humans.
The average person engaged in average activity in a temperate climate can live for three days without water. No exceptions. It’s also a fact that the average person requires at least a half-gallon of water a day to maintain functional health. This can vary depending on age, weight and activity but stands as a viable average. Any less begins to compromise certain biological systems.
But it’s not just about water as a liquid for life. It’s about water as an ingredient in cooking, bathing and personal hygiene – not to mention a needed sustenance for animals, from dogs and horses to chickens, pigs and other livestock. Plants also require water but we generally hope that natural water resources such as rain or irrigation will suffice.
This article focuses largely on scalability. It’s not about constructing a solar still to squeeze a pint or two of water out of the ground on a daily basis. It about collecting water from both existing and found sources and effectively purifying it.
Perhaps the most reliable source of fresh water is natural precipitation.