A 7-month-old should drink 4 to 8 ounces of water per day. That’s roughly half a cup to one cup, offered in small sips throughout the day rather than all at once. At this age, breast milk or formula remains your baby’s primary source of both nutrition and hydration, and water is simply a complement to meals.
Why the Amount Stays Small
Babies get most of their fluid from milk. Formula-fed babies at this age typically consume 6 to 8 ounces per feeding across about four feedings a day, totaling 24 to 32 ounces of formula. Breastfed babies usually nurse four to five times daily, taking in 3 to 5 ounces per session from a bottle when one is used. All of that liquid already contains a large percentage of water, so your baby is far more hydrated than those few sips of plain water might suggest.
The 4-to-8-ounce guideline exists because too much water can displace the calories and nutrients your baby needs from milk and solids. A baby’s stomach is small, and filling it with water means less room for the fat, protein, and iron that fuel growth and brain development during this critical period.
Risks of Giving Too Much Water
Babies are more vulnerable to water intoxication than older children or adults. Their kidneys are still maturing, which means they can’t flush excess water as efficiently. When a baby takes in too much plain water, sodium levels in the blood drop rapidly. This condition, called hyponatremia, can cause irritability, excessive sleepiness, low body temperature, swelling, and in serious cases, seizures. Symptoms typically appear after total body water increases by 7% to 8% or more in a short period.
Sticking to the recommended 4 to 8 ounces per day, spread across mealtimes, keeps you well within safe territory. You don’t need to measure precisely. A few sips with each solid meal is the right general approach.
When and How to Offer Water
The easiest routine is to offer a small amount of water with solid food meals. If your baby is eating solids two or three times a day, a couple of ounces at each meal adds up naturally. Think of it as practice for drinking, not a hydration strategy. Breast milk or formula handles hydration.
At 7 months, you can use an open cup held by an adult. Babies are developmentally ready to start practicing sips from an open cup around 6 months, and with repetition, they gradually learn to close their lips on the rim and control the flow. A small, lightweight cup works best. Straw cups are another option, though many feeding specialists suggest introducing those closer to 9 months. Sippy cups with spill-proof valves are popular but don’t teach the same oral motor skills as open or straw cups.
Tap Water, Bottled Water, or Boiled Water
For a healthy 7-month-old born at full term, plain tap water is fine in most areas. Fluoridated tap water is actually the preferred choice because small amounts of fluoride support developing teeth. You can mix in some non-fluoridated bottled water occasionally, but there’s no need to use it exclusively.
Boiling water before offering it is recommended for babies younger than 2 months, premature infants, and those with weakened immune systems. For a healthy 7-month-old, boiling isn’t typically necessary unless your local water supply has known safety concerns. If you’re unsure about your tap water quality, check your municipality’s water report or use a filter.
How to Tell Your Baby Is Well Hydrated
Wet diapers are the simplest indicator. A well-hydrated infant produces at least six wet diapers per day. If that number drops noticeably, or if you notice any of the following, your baby may be mildly dehydrated:
- Dry or sticky mouth
- Fewer tears when crying
- A sunken soft spot on the head
- Less playful or active than usual
More severe dehydration looks like excessive fussiness or sleepiness, sunken eyes, cool or discolored hands and feet, wrinkled skin, and only one or two wet diapers in a full day. Dehydration in babies most often happens during illness, particularly with vomiting or diarrhea, not from day-to-day feeding. In those situations, your pediatrician will likely recommend an electrolyte solution rather than extra plain water.
Drinks to Avoid Before Age 1
Water and breast milk or formula are the only drinks a 7-month-old needs. Juice, even 100% fruit juice, adds sugar without the fiber of whole fruit and can contribute to tooth decay and loose stools. Cow’s milk as a primary drink isn’t appropriate until 12 months because it’s harder for babies to digest and doesn’t have the right balance of iron and other nutrients. Plant-based milks, sweetened beverages, and flavored waters should also wait.