Introducing Water and a Cup to Your Baby: What Dentists Recommend

Introducing water and a cup to a baby is one of those parenting decisions that seems simple until you discover that there is a whole world of cup types, conflicting advice, and even professional guidance that many parents are unaware of. Here is what the evidence and dental experts actually say.

When to Start Offering Water

Before 6 months, babies who are breastfed do not need any additional water, even in hot weather. Breast milk is over 80 per cent water and provides complete hydration alongside nutrition. Formula-fed babies also do not typically need additional water, though in very hot weather a small amount may occasionally be offered.

At around 6 months, when you begin introducing solid foods, water can be offered alongside meals. This is for several reasons: it helps babies learn to drink from a cup, it aids digestion as the gut begins to process food, and it begins to establish the habit of drinking water with food rather than milk.

In the UK, NHS guidance recommends introducing a free-flow cup (no valve) with water at around 6 months. The emphasis on "around 6 months" and "with meals" is important — this is not an instruction to begin water sessions separately, but to offer sips as part of the weaning process.

How Much Water Does a Baby Need?

Babies under 12 months get most of their hydration from milk — breast milk or formula. Water offered at this stage is supplementary and exploratory rather than essential for hydration. Most babies between 6 and 12 months will only take small sips, which is perfectly normal.

From 12 months, as milk intake naturally begins to reduce and solid food intake increases, water becomes more important. NHS guidance suggests babies and toddlers over 12 months need around 6 to 8 cups of fluid per day (approximately 1.1 to 1.3 litres), the majority of which will come from milk and water.

In warm weather or after energetic activity, a toddler may need more fluid. Signs of adequate hydration include regular pale yellow wet nappies.

Open Cup vs Straw Cup vs Sippy Cup: What Dentists Say

This is where professional guidance is clear but frequently ignored by the baby product industry.

The dental and speech and language therapy recommendation is to move babies directly to an open cup or, as a second option, a straw cup. Both of these require an oral motor pattern that is developmentally appropriate and does not adversely affect tooth development or oral function.

The sippy cup — a cup with a valve or spout that requires the baby to suck rather than sip — is recommended against by the British Dental Association and the Royal College of Paediatrics and Child Health. The reasons are:

1. Dental health: The sucking action used with a sippy cup keeps liquid in contact with teeth in a way that sipping does not. Even when the liquid is water, this prolonged contact pattern can become problematic when the cup is used with milk or juice.

2. Oral motor development: Sipping from an open cup or using a straw requires different oral motor patterns than sucking from a spout. These patterns are more similar to the mature drinking action used in adulthood and better support the development of oral motor skills involved in speech.

3. Habit formation: Sippy cups are easy to carry around and often used throughout the day. This creates a pattern of frequent sipping, which — if the cup contains anything other than water — continuously bathes teeth in liquid, increasing cavity risk.

If you want to use something other than an open cup, a straw cup is the preferred alternative. Straw drinking also develops appropriate oral motor skills and does not have the same tooth contact issues as a spout.

Starting with an Open Cup

An open cup at 6 months sounds messy, and it is. But it is also achievable with the right approach.

Begin with a small, heavy-based cup that the baby can hold. A Doidy cup — an angled design popular for this purpose — or a small standard cup both work. Offer a tiny amount of water (a few millilitres) and help your baby tip it to their lips. Expect most of it to go on the baby for the first several weeks. This is fine.

Some babies take to an open cup quickly; others need more time. There is no need to force the issue. The goal at 6 to 9 months is familiarisation, not efficient fluid delivery.

Timing and Persistence

Many parents offer water once or twice and, when the baby shows no interest or rejects it, conclude that their baby does not like water. It often takes many repeated exposures before a baby accepts water with any consistency — and this is normal. The breastfed baby, in particular, may be confused by the taste of tap water compared to breast milk. Continuing to offer small amounts calmly at mealtimes, without pressure, is the approach most likely to eventually succeed.

Water is the only recommended drink for babies between milk feeds. Fruit juice, squash, flavoured water, and herbal drinks are not appropriate for babies under 12 months and are best avoided or minimised in toddlers too.