Water is everywhere, filling our oceans, rivers, and the air around us. Every time you turn on the faucet, you are using this substance that all living things need to survive. Have you ever stopped to think about where this refreshing liquid comes from? The journey water takes to get to your home is a never-ending cycle that has been happening on Earth for billions of years.
The Water Cycle: Water’s Never-Ending Journey
The source of all the water we use is the water cycle, which constantly moves water around the planet. This cycle begins with evaporation, which happens when the sun heats up water in lakes, rivers, and the ocean until it turns into an invisible gas called water vapor. This pure water vapor rises up high into the atmosphere, leaving behind any salt or dirt.
As the warm water vapor travels higher into the sky, it meets much colder air. This cooling causes the gas to change back into tiny liquid water droplets, a process called condensation. When billions of these tiny droplets collect together, they form the clouds we see floating above us.
When a cloud becomes full and heavy with water droplets, it cannot hold any more liquid. The water then falls back to Earth as precipitation, which can be rain, snow, sleet, or hail. This precipitation refills the places where water is stored on the ground, starting the journey over again.
Hidden Storage: Where We Find Water on Earth
After water falls from the sky, it must be stored somewhere before we can use it. Oceans hold about 97% of all the water on Earth, but this salty water is not drinkable. The freshwater we need is only a tiny fraction of the planet’s total water supply.
Most freshwater is locked away in massive ice caps, glaciers, or stored deep underground. The accessible water we use is found in natural storage areas like rivers and lakes. Rivers are flowing streams of water, while lakes are large, still pools. Sometimes, we build large walls called dams to create reservoirs, which are artificial lakes designed to store water for cities.
Water can also soak into the ground, moving through soil and porous rock layers until it collects in underground areas called aquifers. This underground water, known as groundwater, can be reached by drilling wells. This stored water is what we draw from to meet our daily needs.
From River to Tap: Making Water Ready to Drink
The water we find in nature is not always clean enough to drink, so it must go to a water treatment plant. The process begins with intake, where pumps pull the raw, untreated water from a lake or river into the plant. Inside the plant, chemicals are added to make tiny pieces of dirt and other material stick together.
These sticky clumps, which are heavier than water, sink to the bottom of large tanks in a process called sedimentation. The cleaner water is then moved through filters made of materials like sand and carbon. These filters act like giant sieves to catch any remaining small particles, removing most of the cloudiness and debris.
Finally, the filtered water must be disinfected to kill any germs, bacteria, or viruses. This is often done by adding a measured amount of chlorine, or by using ultraviolet light. After the water is clean and safe, it is stored in covered reservoirs before being sent through a massive network of underground pipes that deliver it straight to your home’s tap.