Jeanette -- you need to find the work of Stina Almroth, who has done most of
the research on the needs of babies in *all* climates for water, and has
found that the best health outcomes result when babies do NOT get any water,
but are only exclusively breastfed for the first 4-6 months of life.  Dr.
Almroth is the wife of Dr. Ted Greiner -- perhaps there is something on his
web page that relates to her work?  You can search the LactNet archives on
Greiner to find out the URL for his web page.  And of course, the World
Health Organization's recommendations on infant feeding state explicitly
that babies do not need water, and they apply to infants in tropical
climates as well as temperate and cold climates.