❾-50%}Categories : Self-Reliance Tags : ways-to-conserve-water and countryside countryside-network for hole homestead how how-to how-to-filter-well-water list long make recycling-water-at-home that the to water-recycling ways-to-conserve-water what. Privacy Policy. November As already discussed, this density of air and water becomes less than the density of pure water. So the main principle used in air-lift pumps is the density difference between water and air.