High School Track·Water hardness soap-suds test
Water hardness soap-suds test
Hard water (high mineral content, calcium/magnesium) produces less soap lather than soft water, a real, simple water-chemistry indicator test.
Where to buy & price
Just examples of where to look and roughly what to expect to pay, get everything from wherever works for you, at whatever price you find.
Free/negligible, reuses soap already at home.
Cold storage / timing
None.
Reagents & materials required
| Water samples (tap, rainwater, bottled/distilled, borehole if available) | 100ml of each |
| Liquid soap | 5 drops per sample |
| Clear jars/bottles with lids | 1 per water sample tested |
Procedure, step by step
- 1
Collect several different water samples, for example tap water, rainwater, bottled or distilled water, and borehole water if you have access to it.
- 2
Pour an equal amount (about 100ml) of each sample into its own clear jar or bottle with a lid.
- 3
Add an identical, small measured amount of liquid soap, for example exactly 5 drops, to each jar.
- 4
Seal each jar and shake it vigorously for the same amount of time, about 10 seconds, for every sample.
- 5
Let the jars sit undisturbed for 30 seconds, then observe and measure the height of the foam layer on top of each.
- 6
Rank the water samples from most lather (softest water) to least lather (hardest water), and record which source produced the least.
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