I think locally sourced spring would be the best, considering the locality of the water. If it´s somewhere close to towns or cities you might need to be aware and test it. Petrol stations for instance can leech fuel into the groundwater. And as tyler said, I´d stay away from distilled, same as RO, that takes away minerals. First I used a water filter from brita, then I bought tons of plastic mineral water and glass mineral water, and now I changed to a water filter from berkey. I got fed up with buying all these plastic bottles and generating huge amounts of waste and all this carrying around pissed me off, then you have the storage space, plus the plastic has so many chemicals in it, no thanks. I think glass mineral water is the 2nd best option, but since that became too expensive I went for a berkey. I also overconsumed on mineral water, to the extend that when I sometimes drink them I get bloated, which I find very strange. I guess too many minerals for an extended period of time wasn´t the best choice. Could have also been the plastic bottles, no idea. But I have no issue with plastic table water (man made water). So can´t really be the plastic there.