How Much Water Does a Household Go Through?
The reference figure is about 3.7 litres a day for men and 2.7 for women — but that counts every drink and the water in your food. Here's what the number really covers, what pushes it up, and how to turn your household's habit into a simple count of bottles.
How much water does a person need a day?
The National Academies of Sciences set "adequate intake" for total water — everything you drink plus the water in food — at about 3.7 litres a day for men and 2.7 for women. Roughly a fifth of it typically comes from food, so the drinks part is closer to 3 litres for men and 2.2 for women. It's an average for healthy adults, not a target to hit to the glass: most people meet it by drinking when they're thirsty and with meals.
What increases how much water you need?
- Heat and humidity — a New Jersey August raises everyone's needs.
- Exercise — see drinking around a workout.
- Pregnancy and breastfeeding — the reference figures are higher for both.
- Illness with fever, vomiting or diarrhoea — see signs of dehydration.
How many cases of water does a household need?
Count bottles, not litres: how many 16.9 fl oz bottles does each person actually drink on a normal day? Multiply by the people and the days, divide by 24, and that's cases. For two weeks, rounded up:
| Household | 1 bottle a day each | 2 a day | 3 a day |
|---|---|---|---|
| 1 person | 1 | 2 | 2 |
| 2 people | 2 | 3 | 4 |
| 3 people | 2 | 4 | 6 |
| 4 people | 3 | 5 | 7 |
| 5 people | 3 | 6 | 9 |
Remember the bottles you don't drink straight: the kettle, the rice, the dog's bowl. If bottled water goes into cooking and coffee, that's often a bottle a day on its own.
Does alkaline water count toward daily intake?
Any clean drinking water counts toward these numbers — tap, spring, purified or alkaline. The best water for staying hydrated is the one you'll actually drink, so pick the taste you like. What the research says, and doesn't.
Sources
- National Academies of Sciences, Engineering, and Medicine. Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate, 2005.
Questions people ask
How much water should a person drink a day?
The National Academies' reference is about 3.7 litres a day for men and 2.7 for women — from all drinks and food together, not water alone. Needs vary with heat, activity and health; your doctor is the one to ask about yours.
Does the 8 glasses a day rule hold up?
It's a rough reminder, not a standard. Eight 8 oz glasses is about 1.9 litres, which for many people is close to what they drink once food is counted separately — but there's no single figure that fits everyone.
Do coffee and tea count?
Yes. The National Academies found caffeinated drinks still add to daily water intake. So do milk, soup and water-rich fruit and vegetables.
How many bottles are in a case?
24 in the 16.9 fl oz case and 12 in the 33.8 fl oz case.