A.C.
Breastmilk is nearly 90% water. Not only does your baby not need water, it can actually interfere with growth and development--it can fill baby (their stomach is only about the size of their fist) with water, rather than nutrient rich milk! In extreme cases, LARGER amounts of water can make babies very ill by causing an imbalance of electrolytes.
Nursing on demand (or not too long schedule) will keep your baby hydrated and healthy. While extroardinarily uncomfortable, the short period of heat exposure is not dangerous. Babies don't have developed sweat glands, so they mostly sweat from their heads. Keep your little one protected from too much direct sun, but don't be OVERLY concerned about the heat.
I didn't site all the references that give the reasons for water not being NECESSARY while breastfeeding. But, I DID want to add that I have never had a problem with getting my daughter to accept water (at the appropriate age)...and I never even had to add sugar. The time to add water to a breastfed diet is when you add solid foods.
http://www.todaysparent.com/baby/foodnutrition/article.js...