How it’s worked out
- About 33 ml per kg of body weight
- About 350 ml more for every 30 minutes of exercise
- About 500 ml more in hot weather or when working outdoors
Example
A 75 kg adult exercising 30 minutes a day in summer: 2.5 + 0.35 + 0.5 ≈ 3.3 litres, about 13 cups.
Tips for hot days
- Keep a bottle with you and sip through the day.
- Pale yellow urine usually means you’re drinking enough.
- In Ramadan, spread your water between iftar and suhoor; see the Ramadan timetable.