A solar still is a box with a sloped clear lid. Dirty or salty water in a tray heats in the sun and evaporates; vapour condenses on the lid, runs down and collects in a separate container. Salt and dirt stay behind.
- Slope the lid to one side so droplets run into the collector.
- Place in full sun, facing south.
- Output is small — a family may need several units.
Some chemicals can carry over with the vapour; it isn’t enough for chemically polluted water. Use food-safe materials.