Water Purification Stages
Run dirty water through screening, coagulation, sedimentation, filtration and disinfection.
About the Water Purification Stages
Free water treatment simulation. Send dirty water through each purification stage and see which contaminants are removed, from debris and clay to bacteria. Built for real-world chemistry, the water purification stages runs instantly in your browser: change a setting or drag an object and the result updates at once, so you learn by trying things out rather than only reading about them.
Run dirty water through screening, coagulation, sedimentation, filtration and disinfection. Use it to explore real-world chemistry ideas at your own pace, then check what you found against the key ideas further down this page.
How to use the Water Purification Stages
- Use the controls to change Switch stages on or off. The simulation reacts instantly.
- Press "Run the water through", "Reset" to start, reset or change what is happening.
- Where you see a glowing handle, object, weight or atom, drag it with your mouse or finger. Everything responds in real time.
- Watch the readouts and graphs update as you experiment, and compare what you see with the key ideas below.
Things to try
- Switch off coagulation.
- Switch off disinfection.
- Run all stages.
- Find the weakest stage.
Key ideas you can learn
- Each stage removes a different kind of contaminant.
- Coagulants make tiny particles clump so they settle out.
- Disinfection with chlorine or UV kills the bacteria that filters miss.
Where this is used in the real world
Water treatment plants protect public health around the world by combining these stages.
Who is this simulation for?
Students, teachers and citizens interested in environmental science, climate and water, who want to see the chemistry behind the headlines.
For teachers: project it on the board, let students predict what will happen, then run it together. For students: change one thing at a time and write down what changes.
Frequently asked questions
Why is coagulation needed before filtering?
Very tiny particles pass through filters. Coagulants make them stick together into larger clumps that settle or get caught.
Why add chlorine at the end?
To kill remaining bacteria and viruses and keep the water safe as it travels through pipes.
Is the Water Purification Stages free to use?
Yes. It is completely free, with no signup, no download and no ads inside the simulation. It runs in your web browser.
Does the Water Purification Stages work on a phone or tablet?
Yes. It uses touch as well as the mouse, so you can drag objects with your finger. A larger screen makes the controls easier to see.