Water distillation is a time-tested purification method that separates pure water from contaminants by exploiting the phase change from liquid to vapor and back to liquid. The process begins by heating impure water in a boiler until it evaporates, leaving behind salts, minerals, heavy metals, bacteria, viruses, and non-volatile impurities. The rising steam travels to a condenser, where it cools and condenses into liquid distillate, collected separately as clean water. The mechanism relies on differences in boiling points and vapor pressure: water vaporizes at ~100°C (at sea level), while most contaminants do not, ensuring effective separation. Advanced systems use heat exchangers to improve efficiency and vent volatile compounds. Solar distillation adapts this principle using renewable solar energy, making it sustainable and ideal for water-scarce, sunny regions. In a passive solar still, contaminated water sits in a shallow, black-lined basin covered by a slanted transparent sheet. Sunlight heats the water, causing evaporation inside the enclosed space (greenhouse effect). The vapor condenses on the cooler cover surface and runs down into a collection trough, yielding 2–5 liters per square meter per day under good sunlight. Active solar stills enhance output with solar collectors, pumps, or reflectors, sometimes reaching 10 liters/m²/day in optimized multi-basin designs. Solar distillation offers major advantages: zero operating costs after installation, no emissions, low maintenance, and decentralized access to potable water in remote or disaster-stricken areas. It effectively removes 99.9% of salts and pathogens. Limitations include weather dependency, low daily output per area, large land requirements for significant volumes, and slower processing compared to mechanical methods. Despite these drawbacks, solar distillation remains a vital, eco-friendly solution for providing clean water, especially in developing countries and arid climates, aligning with global sustainability goals.