Time to Clean...Your Water!

Time to Clean...Your Water!

What goes on behind the tap? Learn how water filters work--and create your own!

Introduction
It’s easy to take our clean water for granted, we’re so used to being able to drink from a fountain or faucet whenever we’re thirsty. But did you know more than a billion people in the world don’t have access to clean water? Part of the problem is that cleaning (or purifying) water is not an easy task. Not only do you need to remove dirt and other debris but you also have to get rid of all the invisible bacteria and microorganisms that can make people sick. In this activity we’ll explore a few methods for cleaning water, and learn about the steps involved in making sure you have safe water to drink when you're thirsty.

Background
Water purification is a complicated and expensive process. It can be broken down, however, into five basic steps: aeration, coagulation, sedimentation, filtration and disinfection. The first step, aeration, adds air to the water, simultaneously adding oxygen to the water as it allows other gases to escape. The second step, coagulation, pulls together the dirt and other solid particles in the water. As they’re pulled together, the dirt coagulates (forms bigger clumps), which are easier to filter out in the next steps of the process. The third step, sedimentation, allows gravity to work for us. It pulls the heavy clumps of dirt to the bottom of the water, separating it even further from the cleaner water at the surface and getting it ready for the next step—filtration. Filtration involves separating the dirt and other solid particles from the water. Finally (and perhaps most importantly) the fifth step is disinfection. We disinfect water by treating it with chemicals and/or heat to remove bacteria and other unsafe microorganisms that can make us sick.