When do you start giving water in addition to milk for a baby?

Water is the elixir of life. Without water no life on earth is imaginable. No wonder that it is one of the most commonly asked questions: When do I start giving water?

Both breastfeeding and formula feeding mothers ask this question regularly in some way. Sometimes mothers ask for addition of certain teas instead of water, but in general there is this big question about how to get enough fluids into their babies.

Water is an essential part of our bodies. While an adult has somewhere between 55 and 70% total body water (depending on how much muscle and how much fat we are made of – obese people having much less body water content), a neonate has just short of 80% total body water. Infants due to their smaller size, thinner skin, reduced body hair, poorer kidney concentration function and inability to care for themselves are at a higher risk of dehydration.

In order to decide when it is time to feed your baby water it is important to look at what the infant feeds. While formula milk has one consistency according to how it is mixed, breastmilk varies during a feed with fore-milk being thinner with less fat content and hind-milk being thicker and more nutrient-dense. Both, cow’s milk-based starter formula and breastmilk, have a water content of about 88-90%.

Your baby grows the fastest it will ever grow in its whole life outside the womb during the first 6 months after birth. The amount of growth depends on the intake of nutrition. If a baby receives water or tea in addition to feeds it will fill up the little tummy and the infant will not be able to stomach a full feed. This means calories will be replaced with water and your baby might not grow well.

Once your baby is 6 months it is useful to add pre-boiled water to the diet when it is a particularly hot day, or when your baby has diarrhoea (in this case water with added sugar and salt such as oral rehydration solution*, rehydrate or sports drinks is more useful than plain water). This is however not needed if your infant is completely or mainly breastfeeding, as the baby will instead feed for a shorter period and more frequently to receive more thirst-quenching fore-milk.

Some people add bottled water to the diet or mix the infant formula with bottled water. This is only recommended if the bottled water used has a low sodium and phosphate content. With too high contents they increase thirst. So boiled water is useful.

In short:
Adding water or tea to the milk feeds is not required in the first 6 months of life and thereafter only in exclusively or mainly formula fed infants during times of high fluid losses (hot weather, diarrhoea). Breastmilk has all the water requirements for infants.

• to mix oral rehydration solution boil a litre of water and add 8 teaspoons of sugar plus half a teaspoon of salt and let cool down.