By the year 2050, the United Nations predicts that more than half of the world’s population will suffer from clean water scarcity, leaving billions with limited access to this basic necessity. A major part of this issue is the fact that over 96% of water on Earth’s surface is in consumable due to the presence of salt. Horizon is a completely passive solar desalination device that could bridge the gap between diminishing resources. Using only heat from the sun, membrane technology, and flowing water, it can reliably remove salt from seawater. No electricity or complex maintenance is needed, so it is a promising solution for places with limited infrastructure at a much lower cost than standard desalination plants. At the optimal operating rate, a device with a 4m2area could provide 3.3 liters of water per hour, effectively supporting communities around the world.