Reviewed by Emily Carter, MSc, RD
Registered Dietitian & Hydration Research Specialist. Emily holds a Master of Science in Human Nutrition and has spent over a decade translating nutrition research into practical, evidence-based guidance for everyday health and athletic performance.
How Much Water Should Kids Drink a Day?
How Much Water Should Kids Drink a Day?
Children need between 1 and 2.4 litres of water per day, increasing with age, activity level, and climate. The Canadian Paediatric Society (CPS) and the Institute of Medicine provide age-specific targets: toddlers (1–3 years) need 1.3L total fluid, school-age children (9–13 years) need 1.6–2.1L, and active teens need up to 2.5L or more. Unlike adults, children have less body mass to buffer dehydration — a 2% fluid deficit hits them harder and faster.
Why Children Dehydrate Faster Than Adults
Children aren't just small adults. Their physiology makes them more vulnerable to dehydration for several reasons:
- Higher surface-area-to-body-mass ratio: Children lose more fluid through their skin relative to body size
- Less efficient sweating: Young children's sweat glands are less developed; they rely more on respiratory evaporation for heat regulation
- Faster metabolic rate: Higher cellular activity per unit of body weight increases water demand
- Unreliable thirst response: Children often don't notice or respond to thirst during play or activity
- Smaller stomach capacity: They can't take in large volumes at once — hydration must be more frequent
These differences mean parents and caregivers can't rely on children to self-regulate hydration reliably.
Water Intake by Age — The Complete Guide
Infants (0–12 months)
Infants under 6 months should receive all fluid from breast milk or formula — no supplemental water is needed or recommended. After 6 months, small amounts of water can be introduced with solid foods, but breast milk/formula remains the primary fluid source.
Warning: Giving water to infants under 6 months can cause water intoxication (hyponatremia) — a dangerous dilution of blood sodium. Do not give infants plain water before 6 months without medical direction.
Toddlers (1–3 years) — Target: 1.3L/day total fluid
At this age, milk remains an important fluid and nutrient source. Water should be introduced as the primary drink outside of milk. Juice should be limited to 125ml (4 oz) per day maximum.
Practical tip: Small cups, sippy cups, or short water bottles they can carry themselves increase intake significantly.
Preschool (4–8 years) — Target: 1.6L/day total fluid
See our guide to the best water bottle for kids and families for age-specific recommendations.
Children in this range are becoming more physically active. School days, outdoor play, and sports all increase fluid demand. Pack a water bottle for every school day — children won't ask for water when they're focused on activities.
The CPS recommendation: Water and milk are the only drinks children need. Juice, sports drinks, and flavoured beverages are not recommended as daily beverages for young children.
School Age (9–13 years) — Target: 1.6–2.1L/day
Teachers supervising active students face their own hydration challenge — see our best water bottle for teachers guide.
See our guide to the best water bottle for school for the right size and features by age.
Girls: 1.6L/day | Boys: 1.9–2.1L/day
This age group is typically more physically active and may underreport thirst. Sports participation significantly increases needs — active kids during a 90-minute soccer game may lose 500–750ml.
Teens (14–18 years) — Target: 1.8–2.6L/day
Girls: 1.8L/day | Boys: 2.6L/day
Teens have adult-level fluid needs. Active teenage athletes — particularly in summer — may need 3L+ on training days.
Daily Water Targets by Age — Quick Reference
| Age | Daily Fluid Target | Primary Sources |
|---|---|---|
| 0–6 months | All from breast milk/formula | No plain water |
| 6–12 months | Breast milk/formula + small water amounts | Introduce with solid foods |
| 1–3 years | 1.3L | Water + milk |
| 4–8 years | 1.6L | Water + milk |
| 9–13 (girls) | 1.6L | Water, milk, some food-sourced |
| 9–13 (boys) | 1.9–2.1L | Water, milk, some food-sourced |
| 14–18 (girls) | 1.8L | Water + food |
| 14–18 (boys) | 2.6L | Water + food |
> Activity adjustment: Add 500ml per hour of physical activity in moderate conditions; up to 750ml per hour in hot weather.
Signs of Dehydration in Children
Children often don't communicate thirst well — watch for:
Mild dehydration:
- Dry lips and mouth
- Less frequent urination (or fewer wet diapers in infants)
- Slightly darker yellow urine
- Irritability or unusual fussiness
- Reduced energy during play
Moderate dehydration:
- No tears when crying
- Eyes appear sunken
- Skin tents (when you gently pinch and release, it stays tented briefly)
- Urinating less than 3 times in 24 hours
- Significant lethargy
Severe dehydration — seek medical care immediately:
- No urine for 8+ hours (infants) or 12+ hours (older children)
- No tears, very dry mouth
- Sunken fontanelle (soft spot) in infants
- Extreme lethargy, difficulty waking
- Rapid breathing
For a full reference on dehydration signs, see signs of dehydration in adults — the principles apply to older children and teens.
For older kids, teens, and active parents — a bottle they can carry all day removes all the friction. The Mammoth Mini 1.5L is sized perfectly for teenagers and students who need a full day's hydration in one container. Shop Mammoth Mini
What Kids Should Drink (and What to Avoid)
Recommended:
- Water — primary beverage at all ages post-infancy
- Milk — provides hydration plus calcium and vitamin D; full-fat until age 2, then 1–2% after
- Herbal teas (no caffeine) — occasional, cooled
Limit:
- 100% fruit juice — max 125ml/day for 1–6 year olds; 250ml/day for older children
- The natural sugar in juice is significant; it's not equivalent to eating fruit
Avoid:
- Sports drinks — not necessary for most children; designed for elite athletes with significant sweat losses
- Flavoured water with sweeteners — artificial sweeteners are not recommended for young children
- Sodas and fizzy drinks — high sugar, phosphoric acid, zero nutritional value
- Energy drinks — never appropriate for children; significant caffeine, stimulants
Practical Strategies to Get Kids to Drink More Water
Make water visible. Children drink more when water is in front of them. Keep a filled bottle at the table, in their backpack, on their desk.
Let them choose their bottle. A water bottle a child picked themselves — their favourite colour or character — gets used far more than one they didn't choose.
Infuse it. Sliced cucumber, mint, lemon, or berries make water more interesting without adding meaningful sugar.
Routine anchoring. Water with every meal, before school, after school, and at bedtime is a simple schedule that builds habit.
Model it. Children mirror adult behaviour. If they see you drinking water consistently throughout the day, they will too.
Don't wait for thirst. Offer water proactively — especially before, during, and after outdoor play, sports, or hot days.
Hydration During Sports and Physical Activity
Active children lose significant fluid during sports. Parents should:
1. Pre-hydrate: Ensure children drink 300–500ml before activity
2. During activity: Offer water every 15–20 minutes — don't wait for them to ask
3. Post-activity: Encourage drinking until urine returns to pale yellow
Sports drinks are only appropriate for children engaged in competitive sport lasting more than 60–90 minutes in heat. For recreational sport, water is always sufficient.
For specific sport hydration guidance, the principles in water intake for athletes apply to teen athletes.
FAQ: Hydration for Kids
How much water does a 5-year-old need?
The Institute of Medicine recommends approximately 1.6L of total fluid per day for children aged 4–8 years, including water, milk, and food-sourced fluid.
Can kids drink too much water?
Overhydration (hyponatremia) is rare in children but can occur if large volumes of plain water are given to very young children or during extreme prolonged exercise. Normal drinking habits in healthy children don't pose this risk.
Is it okay to give kids flavoured water?
Plain water is always best. Small amounts of natural flavouring (lemon, cucumber) are fine. Sweetened or artificially flavoured waters are not recommended for young children.
What's the fastest way to rehydrate a sick child?
Oral rehydration solutions (like Pedialyte) are more effective than plain water for children with diarrhoea or vomiting, as they replace electrolytes lost through illness. Plain water is fine for mild dehydration without GI symptoms.
Should kids drink sports drinks?
Only for prolonged competitive sports in heat lasting 90+ minutes. For school sports, recreational activity, and most kids' games, water is adequate and sports drinks are unnecessary.
How do I get my child to drink more water?
Visible water, routine anchoring, letting them choose their own bottle, and modelling hydration behaviour are the most effective strategies. Avoid replacing water with juice or flavoured drinks as a solution.
Does milk count toward daily fluid intake for kids?
Yes — milk contributes significantly to daily fluid needs and also provides calcium, protein, and vitamin D. It's an important fluid source for young children (ages 1–8 especially).
What colour should my child's urine be?
Pale yellow is ideal. Colourless may indicate overhydration (rare). Yellow to amber means they need more fluid. Dark amber, orange, or brown requires immediate fluid increase and medical attention if it persists.
- Signs of Dehydration in Adults
- Benefits of Drinking Water
- How to Stay Hydrated
- Water Intake for Athletes
- Best Water Bottle for Kids
The Mammoth Mini 1.5L is the right size for older kids, teens, and students who need a full day covered in one container. Shop Mammoth Mini
