Ok...this scares me.?

we had a pretty bad drought this year. i watered my garden and nothing grew, nothing produced all summer. in the past couple of weeks we have had some great and much needed rain. all of a sudden everything has new leaves and producing fruit and vegies (what has survived anyways). if the plants were dieing eventhough i watered using the hose, what exactly is in the water if it is supposed to be good clean water? what exactly are we doing to our own bodies by ingesting the water from our own faucets?