Your water supplier probably makes available yearly water quality reports like these: http://phoenix.gov/residents/waterandsewer/… You can find out what's in your water. As an aside, local agriculture extension people tell us our water pH and mineral content hardly vary at all anyplace served by City of Phoenix water, so there is no point having our water tested - we can look it up. I am surprised at all the people I see here in the US who won't drink anything but bottled water. Most bottled water has been purified by reverse osmosis and addition of ozone (which kills anything living unless it has plenty of enzymes to degrade ozone, which most bacteria don't) and/or ultraviolet light. This RO bottled water has negligible amounts of necessary dietary minerals. Sometimes the manufacturer adds back some minerals but the amount added is very small, and the situation is akin to adding a few vitamins back into fluffy white bread. Spring water is often available and does have minerals. But unfortunately it sometimes is treated by reverse osmosis as well. Most humans get almost all their calcium from the water they drink and use for cooking. Most humans barely get enough calcium; it binds tightly to other compounds in the intestine and very little is absorbed. When home RO machines were first sold about 20 years ago, they contained labels warning that RO water should not be used for cooking or drinking, because of the lack of minerals. This seems to have gone away, I suspect because bottled water manufacturers make a lot of money. I worry we are headed for an epidemic of osteoporosis among RO drinkers. In the US, standards for tap water are incredibly stringent. There are no standards whatsoever for bottled water. You are trusting the manufacturer to provide a clean product. Municipal tap water anyplace in the US is safer than any bottled water. The only exception is for people who are immunosuppressed, because there are a few water-borne pathogens that are not killed by chlorination, but are killed by ozone. I drink tap water and I won't drink RO bottled water. As for bulb content - if you fall down and break your hip due to osteoporosis due to drinking reverse osmosis water, somebody will have to water your bulbs while you recover (if you survive) and they won't do as good a job as you do. Leo Martin Phoenix Arizona USA