<p>Industrial cooling towers discharge substantial amounts of water vapour, and this remains a largely untapped resource. Here, inspired by termite mound thermoregulation, we present a four-tier water-recovery architecture to bridge this gap. The primary tier utilizes a heterostructured microsphere coating to achieve a capillary-driven nucleation rate of 33.6 g m⁻² min⁻¹, while enabling 1.7 °C of radiative sub-dewpoint cooling via gradient-refractive index spines. The secondary tier integrates an inverted-pyramid composite that acts as a mechanical shield to enlarge the heat-transfer area. Subsequently, the tertiary tier establishes a radiative cooling-dominant gas–liquid heat-transfer scheme with a net power of 133.7 W m⁻². Finally, the quaternary tier employs biomimetic flow channels to suppress vapour dispersion and sustain a self-sustaining ‘condensation–radiative cooling–recondensation’ cycle. Operating passively, the system achieves a recovery rate of 41.6 kg m⁻² day⁻¹ and an 83% retention rate. For a 300-MW plant, this yields 2.7 × 10⁸ tonnes of annual water savings, meeting the domestic needs of 2.2 million households.</p>