Atmospheric water harvesting as a sustainable and resilient resource in arid climates: gaining insights from ancient techniques

ABSTRACT Fog and dew, or atmospheric moisture, are valuable complementary resources. Ancient civilisations exploited these resources in harmony with the environment, though information on their techniques is fragmented. This review provides insights into the efficiency, evolution, and relevance of ancient atmospheric water harvesting (AWH) techniques from 5000 B.C. to the 1900s, alongside modern techniques. An analytical framework and assessment are presented to deduce their viability for replication, revival, restoration, or redevelopment. Modern fog collectors yield an average value of 3–10 L/m2/day and dew collectors 0.3–0.6 L/m2/day. Ancient fog collectors from Mexico and Chile resembled modern collectors, while fog drip from trees offers a natural alternative, collecting 10 L/m2/day. The stone drip method shows potential in urban areas with extensive concrete surfaces. Ancient dew collection techniques include alchemists' dew collectors, lithic mulching for soil water conservation, dew ponds for water retention, and stone-pile condensers, which collected up to 360 L/day. Air wells, however, were less effective. Ancient AWH techniques offer valuable insights and can effectively supplement modern collectors, enhancing resilience and water security, especially in arid regions. Implementing AWH techniques provides sustainable, decentralised, nature-based strategies on a micro and macro scale for mitigating contemporary water shortages amidst increasing climate challenges.