It's very simple actually :) The 'good critters' in the water kefir eat the
Sugar - the longer it ferments, the less sweet it becomes...until it finally has no
Sugar at all in it (and is VERY tart).
I don't know about the various brands of spring water, but I do know that you don't have to use spring water (I've always used RO water).
It's much (much!) easier to make dairy kefir - and I think it's far more beneficial, too.
You do not *have* to use raw milk for dairy kefit to be beneficial (but raw milk is always best). You can NOT use any milk that is "ultra pasteurized" (organic or not); it will kill the grains.
You can learn ALL about kefir-making here:
http://users.sa.chariot.net.au/~dna/kefirpage.html#what-is-kefir
(there are many reports that the site owner --who was once very reputable-- has not been filling orders after receiving payment, so I doubt I'd buy from him).
We currently don't have any water grains - here's where we got ours originally:
http://kefirlady.com/
(and I HIGHLY recommend her!)
You live in a state where raw milk is very available. Here's a link to find a supplier close to you:
http://www.realmilk.com/real-milk-finder/
I think dairy kefir is the easiest ferment to make. Sauerkraut & kimchi are both very easy, too (of course, it's almost always going to take a 'couple of batches' to get the hang of it). You can Google "lacto-ferment" and "recipe" and find TONS of easy recipes & options!
You can lessen (or eliminate) the salt you use for most ferments, by using the whey you get by making the dairy kefir. To make sure you have whey when making dairy kefir, just ferment the kefir until it separates into 'curds & whey' - and then strain it through a linen bag or towel, or corner of a pillow case. After you've separated the whey, what is left will be VERY similar to creamed cheese :)
Blessings,
Uny