Drinking water can be labeled "filtered", "purified", "distilled" or "reverse osmosis" or none of the above.
"Distilled" water, if the producer runs a clean shop is ok, but minerals may be eliminated by the process, so there is the hazard that drinking it exclusively will flush electrolytes from your body.
"Reverse osmosis", if done with sufficiently small micked filters which get properly serviced, can eliminate microbes but not most minerals. Undersink reverse osmosis filtering systems have long been on the market, and not all are bogus.
"Purified" and "filtered" — well yeah, with what and how, and how serviced hygienically? Tour the plant and ask questions? Yeah, sure. Once I saw some chopos filling big blue botellons with a garden hose, then shrinking the blue plastic caps on with a hair dryer. The bottles and the caps are readily available at large ferreterias.
The botellons are your best bet if you don't have an R/O machine or collect rain water. Find a good vendor and stick with them.