Vintner's Cellar uses only Ultra-Pure reverse osmosis water in our concentrated wine kits.

This proven technology is one of the most effective forms of water treatment available today.  It is a process which typically removes 95-99% of dissolved matter from the water, including harmful contaminants such as lead, arsenic and nitrates. They also remove a high percentage of added fluoride. It is the best technology available for the removal of chloramines, which many city water systems now use instead of chlorine and can make disinfection afterward much more efficient and effective. 
Taste is obviously very subjective, but RO water is usually rated as better tasting than tap water by people who directly compare the two in blind taste tests, according to the National Rural Water Association. Lead, iron, nitrates, sulfur-based compounds and various chemical residues often make tap water unpalatable. The removal of these substances by reverse osmosis can give drinking water a cleaner or fresher taste.