This article is from the WineMaking FAQ, by malak@CAM.ORG (Don Buchan) with numerous contributions by others.
When making wine that calls for water, care should be taken not to use
any kind of water from any source.
One rule that is generally agreed upon is that chlorinated water,
particularly during the summer when levels are usually higher, is not
good for winemaking. While it will work, the chlorine in the water may
react with the ingredients and produce a slight off flavour. It is
also bad for yeast and therefore could slow down the yeast's ability to
ignite in the wine.
Generally you can use either distilled (or reverse osmosis) water or
spring water. Distilled and reverse osmosis water are ultra-pure waters
that have next to no dissolved solids and therefore no tastes. All
tastes will therefore develop from your fruit and/or concentrates and
fermentation. Spring water may add a slight taste to your wine, though
usually not a significant taste.
The editor frequently uses water from various surface and artesian
wells with great success. Generally they should be regularly tested to
be free from infections and should be low in dissolved solids. Artesian
wells are usually sterile, but may be high or low in dissolved solids
depending on the well. Care should be taken that the water be suitable
as it may contain, depending on your area, agricultural wastes or
fertilizers or pesticide that may be detrimental to your wine and
fermentation. If you're not sure, either use distilled water or bottled