Water Taste Test
Warren Marchioni
1991 Woodrow Wilson Biology Institute
Purpose
The following exercise is designed to be used at all ability levels and can be used in an introduction to a unit on water pollution. Most youngsters are not aware that the composition of water is generally not pure and that the lack of uniformity makes samples from different sources vary in taste.
Background
Taste is a limited sense in humans but working in conjunction with olfaction, the subtle differences among specimens of water samples should be distinguished by most students. The rating system used to judge the quality of the water sampled reinforces the concept that water is not just H2O.
Procedures
Inform students that they are to sample five different examples of drinking water from nearby municipalities. (These samples can be collected from friends or family members living in other towns). Be sure to include one sample from a school fountain -- several students surprisingly will recognize it. Include also a sample of a store-bought bottled water. Students are to taste at least 3 oz (90 ml) of each unknown water sample at room temperature. Their analyses should be described in the form below.
| Sample | Clarity | Odor | Taste
Description | Taste
Evaluation |
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| A |
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| B |
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| C |
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| D |
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| E |
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Taste Evaluation Rating Scale
- 5 = excellent
- 4 = very good; would drink it daily
- 3 = fair; OK for cooking
- 2 = inferior; strictly for bathing
- 1 = terrible; wouldn't wash my dog in it
Analysis
Combine results from all students and tabulate the agreements and disagreements about the quality of the water samples. Speculate on what would account for differences in taste. For example, many store-purchased waters are sold in plastic containers which often tend to impart a taste to the water.
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Woodrow Wilson Index
