NEXT WHY なぜのつづき
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Society / Life

Why must water be treated before use?

Short answer

Water is treated so people can use it for a specific purpose, such as drinking or a factory process. Treatment can remove dirt, chemicals, or germs that could make people sick. The source and purpose affect which steps are needed.

One example: making drinking water

Here is one way a treatment plant can make drinking water from river water:

A three-step example of treating river water for drinking: a chemical gathers tiny dirt bits, clumps settle and the water passes through sand, then chlorine or another disinfectant acts on germs that remain.
One example of making drinking water from river water. The steps used depend on the source and the condition of the water.
  1. Bring tiny particles together: A chemical is added and mixed in. It helps tiny bits of dirt stick together into larger clumps.
  2. Let them settle, then filter: The clumps sink. The clearer water above them passes through a layer of sand, which catches more small particles.
  3. Disinfect: A disinfectant such as chlorine kills germs that may remain in the water.

This is one example. Plants choose steps based on the source water; some add steps to remove odors or certain chemicals. They also check the finished water and care for their equipment to help keep drinking water safe.

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