Author: Laurel Hamers / Source: Science News for Students
People are used to turning the handle on a sink and seeing a stream of clear water pour forth.
But where does this water come from? Typically, a town will pump it from a river, lake or groundwater aquifer. But this water can host an array of germs and solids — waterborne dirt, rotting plant bits and more. That’s why a community will typically process that water — clean it — through a series of steps before sending on to your faucet.The steps of water treatment
The first step is usually to add coagulants (Koh-AG-yu-lunts). These are chemicals that cause those solid bits to clump together. Even if those solids didn’t hurt you, they could cloud water and give it a funny taste. By making these bits clump, they become bigger — and easier to remove. A gentle shaking or spinning of the water — called flocculation (FLOK-yu-LAY-shun) — helps those clumps to form (1).
Next, the water flows into big tanks where it will sit for a while. During this settling period, the solid sediments begin to fall to the bottom (2). The cleaner water atop it then moves through membranes. Like a sieve, they filter out smaller contaminants (3). Then the water is treated with chemicals or ultraviolet light to kill harmful bacteria and viruses (4). Following this disinfection step, the water now is ready to flow through pipes to…
The post Explainer: How is water cleaned up for drinking appeared first on FeedBox.