Have you ever gone to the beach and dug into the sand until you hit water? Sand traps water that's easy to get to. Sand is easy to dig. That's how to get water from sand. If only you could do that in a dry place like Africa. You can!
This video explains what a sand dam is. If you watch to the end, you'll actually see an African community building a dam. Then you'll know how to build one too!
Many places in Africa have dry river beds. During the rainy season, the river is full. All that water rushes to the ocean. When the water sweeps along, it brings with it sand. During the dry season, water is scarce.
It's possible to build a dam in such a way that lets water travel to the ocean but traps the sand. After 2 or 3 seasons, the sand builds up behind the dam. When the rainy season comes, a lot of the water gets trapped in the sand. The trapped water remains through the dry season. People can either dig into the sand to harvest the water, or use a pipe that's tapped into the side of the dam.
It still seems like a lot of work to have to walk to the dam and harvest the water but there are two benefits:
- When you get to the dam you are pretty much guaranteed to find water.
- The sand acts as a filter, keeping the water clean.