Age guide
Water intake by age
Adults
For most healthy adults, weight, activity, climate, and food intake explain more than age alone. A body-weight calculator is the best starting point.
Use age as a habit signal: busy adults often under-drink because the day gets away from them, not because their formula is different.
Older adults
Older adults can have a weaker thirst signal and may be more affected by heat, illness, and medication routines.
Regular small drinks with meals, medication times, and morning routines are usually more effective than relying on thirst alone.
Children and teens
WaterDailyGoal is built for adults. Kids and teens need age-specific guidance, especially around sports, illness, and heat.
For children, use pediatric guidance instead of adult calculator targets.
Frequently asked
Do older adults need more water?
Not always, but they often need a more deliberate routine because thirst can be less reliable and heat or illness can become risky faster.
Can kids use the adult calculator?
No. The calculator is general adult wellness guidance. Children should follow pediatric or clinician guidance.
Sources
- 1.U.S. National Academies (IOM/NAM), 2005 — Adequate total water intake of about 3.7 L/day for men and 2.7 L/day for women, including water from food and all beverages.
- 2.European Food Safety Authority (EFSA), 2010 — Adequate total water intake of 2.5 L/day for men and 2.0 L/day for women under temperate conditions.
- 3.Mayo Clinic — General guidance of roughly 2.7–3.7 L of total fluids a day, with thirst and pale-yellow urine as everyday checks.
- 4.World Health Organization (WHO) — Notes that daily water requirements are individual and rise with temperature, physical activity, and illness; general adult needs are commonly put on the order of 2–3 L of total water per day.