How much water do you actually need in a day?
The eight glasses figure has no strong scientific basis — it appears to be a misreading of a 1945 recommendation that also noted most of it comes from food. Actual needs vary with body size, activity, and especially climate, and in Indian summers requirements are substantially higher than in temperate countries. A practical guide is urine colour: pale straw is fine, dark yellow means drink more, completely clear may mean you are overdoing it. Around 20 to 30 percent of intake comes from food. Thirst is a reasonably reliable signal for most healthy adults under 65.
Answers
Worth noting thirst becomes less reliable with age. My father genuinely does need reminders.
The urine colour check is far more practical than counting glasses. Adjusts itself for the weather automatically.