Activated carbon's tiny holes trap particles that slip through coarser materials. In this project, you pour water through a filtering tube packed with layers of charcoal, sand, and gravel. The layered filter traps tiny particles that the strainer and settling missed.

Water treatment plants use materials like charcoal, sand, and gravel every day to clean water. In this project, you build a simple version of their filtration system. The layered filter does the heaviest work, trapping tiny particles that the strainer and settling missed.

Sedimentation is when particles in water sink and settle on the bottom. In this project, you let strained water sit in a tube so fine particles sink to the bottom. This settling step uses gravity to pull dirt downward, separating it from the water above.

Purification often works in stages, where each step catches what the last one missed. Pouring dirty water through a strainer removes the largest particles. Letting that water settle in a tube lets fine particles sink to the bottom. Then comes the layered filter — charcoal, sand, and gravel packed together. Each material grabs different-sized bits of dirt, so stacking them removes more contamination than any single material alone. The layered filter does the heaviest work, trapping tiny particles that the strainer and settling missed.