Nearly every popular U.S. brand of spring or mineral water that I've seen has a kosher certification symbol on the bottle. Amonng them are Perrier and Saratoga (mineral / sparkling) and Poland Spring and Fiji (Spring Water).
All these brands are bottled at the "source" according to the label. Even without that labeling, it is just water, as far as I can tell. I'm unaware that any of these companies bottle anything else in their plant (I have been to the Saratoga plant, and they don't seem to bottle or have anything else) besides water.
What concerns are there that would require the certification?