The short answer
There is no single rule. The US National Academies give an average total of about 2.7 liters a day for women and 3.7 liters for men, but that includes the water in food, and they say thirst is a fair guide for most healthy people. The NHS suggests 6 to 8 cups or glasses of fluid a day.
What the sources say
- Women "consume an average of approximately 2.7 liters (91 ounces) of total water, from all beverages and foods, each day, and men average approximately 3.7 liters (125 ounces) daily." About 80 percent comes from drinks and the other 20 percent from food. The panel added: "We don't offer any rule of thumb based on how many glasses of water people should drink each day," and suggested "letting thirst be their guide" (US National Academies, 2004).
- The NHS says "people should aim to drink 6 to 8 cups or glasses of fluid a day," and enough "so their pee is a clear pale yellow colour" (NHS, Water, drinks and hydration).
So the 3.7 and 2.7 liter figures are not drinking targets. If about 80 percent comes from drinks, that is closer to 3 liters for men and 2.2 for women, and less in cool weather or on a quiet day.
Set it up in Landmark
Landmark reads water from Apple Health, so it needs something that writes it: a water or food logging app, a smart bottle that syncs to Health, or entries you add in the Health app.
- Open the Goals tab and tap +, then Habit, then Water.
- Choose Each day and type your target in liters.
Today shows how much is left before the day ends.
