How clean is our water? Testing water samples
Compare tap, well, river and pond water by appearance, pH and hardness, using distilled water as a control.
Core concept
In short: Test water samples by look, pH and hardness to find the cleanest.
Water quality can be compared using appearance, pH and hardness tests
Topic: Water and the environment
Water from different places can look and behave very differently. Looking closely shows particles of mud or algae. Universal indicator: A substance that changes colour to show whether something is an acid or a base. All key words shows whether water is acid: A substance that tastes sour, like lemon juice or vinegar. It turns blue litmus red. All key words, neutral: Neither an acid nor a base, like pure water. All key words or basic. The soap test shows whether water is hard. None of these tests can show germs, which need a microscope or a laboratory test, so even clean-looking water may not be safe to drink.
What you will learn
- Compare water samples by appearance, pH and hardness.
- Use distilled water as a control.
- Suggest possible causes of poor water quality and explain the limits of simple tests.
Before you start
- Know how to use universal indicator and the soap test.
Materials
- Tap water, well water, river water, pond water and distilled water
- Universal indicator
- Soap solution
Equipment
- 6 test tubes in a rack
Procedure
- Add a water sample to a test tube and look at it closely.
- Add universal indicator, stir, and read the pH.
- In another tube, add soap solution to a sample, shake (stir), and look at the lather.
- Test as many samples as you can and record your results in a table.
How this simulation is simplified
- Each sample is shown with typical properties for its source. Real samples vary from place to place.
- These simple tests cannot detect germs or harmful dissolved chemicals.