Answer: It's an interesting experiment to try. I'm afraid, however, that the differences between the different types of water will be so subtle that you may not be able to notice any difference, especially if you are only growing a few plants for each treatment.
I have another idea for a test! You might try to mimic various environmental factors and how they affect seed germination. For example, water one set of seeds with a vinegar (or lemon juice) solution to mimic acid rain; another with vegetable or motor oil solution to mimic an oil spill; another with salt water solution to mimic road salt spray. Can you think of any other environmental conditions you could explore?
You can test these substances in various concentrations, and even apply them in various ways (soak seeds, spray on seedlings, apply to soil, etc.)
Good luck with your experiment!
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