I hope your joking about watering your plant with fiji water (which is imported from fiji???)...
think about it. not only are you going to the store and spending money on something that is already being delivered to your home at virtually no cost, you're also adding pollution and waste from the transport and packaging of...WATER. I'll have myself a seltzer or a perrier from time to time, but i find even drinking bottled water is retarded. And I'm not a tree-hugger by a long shot, this is just one place where you can easily avoid adding to the trash and co2 you produce each year.
If you want the absolutely best and purest water for your hydro system, go out and get yourself some distilled water in gallon jugs at CVS. If you're growing in soil, get a bucket, fill it up with tap water, let that shit sit for a day or two and the ph should be fine. Or just collect rainwater with it. If you want to go fancy get an air pump to bubble it or better yet an RO system, but for the love of god don't buy bottled water and feed it to your plants. Most of this will have the same mineral composition of your tap water, so you're giving money to the coca-cola company and adding trash and pollution....bottom line is it's fucking water, which as far as your plants are concerned is H20 and nothing else. If you want to add nutrients to your plants, go to the hydro store.
On a side note, anyone ever thought about the environmental impact of growing indoors? Most of us get our electricity from coal fired plants, so what we are doing isn't exactly good for the planet...i'm not sure the little bit of O2 our ladies put out is going to have a huge impact considering the electricity need to run all our lamps, fans and the other gadgets. If it weren't for politics, i think most of us would be growing our plants outdoors where they belong. Don't get me wrong, indoor growing has it's place in the winter or for providing a tightly controlled environment for seedlings, but let's face it plants belong under the sun not in a closet.