The answer is still "no" SEE Why babies under six months don't need water
Even when it is very hot outside, exclusively breastfed babies still do not need additional water. On such days, you'll notice that little ones tend to nurse more frequently, but for a shorter duration each time. What's happening here is that they are getting plenty of thirst-quenching foremilk, which keeps them well-hydrated.
This also means that mummy needs to drink plenty of water so she can keep up with her baby's increased demand for milk on a hot day.
Formula-fed babies too don't need extra water on hot days; you just need to increase the frequency of feeds and make sure you prepare the formula according to instructions.
In cases when a baby becomes dehydrated or very sick with a tummy bug (that causes excessive loss of bodily fluids), then his doctor may advise that you give the appropriate dosage of an oral rehydration solution (not water).
When exactly can you give baby water, and how much of it can you give?
When to give water to newborns and infants up too 6 months of age?
These babies should not be given water in addition to breastmilk or formula, unless on medical advice.
When to give water to babies between 6 and 12 months of age?
Once your baby is six months old, it's okay to give tiny sips of water to help him get used to a sippy cup. Around two ounces per 24 hours is the expert-recommended amount of water to be given at this age. Any more than this may interfere with his milk intake, which is still much more important at this stage.
When your baby starts solids, give a small amount of water after his meal to prevent constipation. Don't let water replace breastmilk or formula, however.
As your baby approaches his first birthday, you could increase the amount of water he drinks in keeping with his increased activity levels.
NOTE: An adequate fluid intake is essential for your active toddler.
When to give water to babies aged 12 months and above?
By this age, your little one will probably have reduced his milk intake and increased his solid food consumption to three meals a day plus snacks.
Due to these factors in combination with increased physical activity levels, your baby's water intake will naturally increase.
The United States Department of Agriculture recommends that toddlers get around 1.3 liters of liquid water a day (around 4.23 cups). This is not restricted to just water and could include water from all sources of food and drink, including milk.
If you have trouble getting your energetic toddler to drink enough fluids, try introducing water in a fun, colorful sippy cups or drop an ice cube in his cup. You could also include water-rich foods in his diets such as watermelon, grapes, and various kinds of soups.