How often should you drink water? Not how much

Question

We all know how much water we should be drinking. However, I have a close friend that only drinks 1.5 litres of water once a day. Keep in mind that they do consume other liquids with food. Nevertheless, this seems completely unhealthy and backwards to me.

If someone drinks their only water source once a day, I imagine the body will metabolise or otherwise use all the water nutrients right away and dispose of the rest. I do not have any evidence to back up my claims, but this seems like a gross misinterpretation of health guidelines and their body will be wanting water later in the day.

Anybody seen any articles that set quotas on drinking frequency?

Answer 1

Referring to published research, there is no known quota on drinking frequency since fluid intake from beverages and food in time period takes care of the total hydration status of an individual in a day. Daily consumption below the range of adequate intake of water may not produce harmful effects to the body because hydration is received from intake of beverages and foods other than the normal water intake.

Research into hydration reveals humans must maintain water balance in order to stay healthy. Humans receive hydration i.e. water from daily food and water intake, and generally lose water in the form of sweat, urine and exhalation. Drinking water is beneficial in those with a water deficit particularly due to dehydration which can be caused by other factors such as diarrhea, vomiting, burns etc.

The recommendations on adequate intake of water which includes total water intake (water from beverages and food) is found here.

Over the course of a few hours, body water deficits can occur due to reduced intake or increased water losses from physical activity and environmental (e.g., heat) exposure. However, on a day-to-day basis, fluid intake, driven by the combination of thirst and the consumption of beverages at meals, allows maintenance of hydration status and total body water at normal levels.

Answer 2

In a recent Time magazine article, they reference a 2015 study in The American Journal of Clinical Nutrition about recommended water drinking frequency, "A randomized trial to assess the potential of different beverages to affect hydration status: development of a beverage hydration index:"

Sipping water (or any other beverage) a little bit at a time prevents the kidneys from being “overloaded,” and so helps the body retain more H2O, Nieman says.

The take-home message isn’t that people should drink less water, nor that they should swap out water for other beverages. But for those hoping to stay optimally hydrated, a slow-and-steady approach to water consumption and coupling water with a little food is a more effective method than knocking back full glasses of H2O between meals. “Water is good for you, but you can drown in it too,” Nieman says.

The entire article is worth a read and might drastically change the way the public views hydration: "Why Drinking Water All Day Long Is Not the Best Way to Stay Hydrated."

Answer 3

Physiologically speaking, it is probably the most rational to drink 250-500 mL of water at once. The frequency of drinking depends on the amount of water you need. If you need 2 L per day, you can drink 4 x 500 mL and if you need 5 L per day (which is quite possible when working on a hot day), you can drink 10 x 500 mL.

Drinking 1.5 L of water at once, once a day, by an adult should not be harmful in terms of water intoxication (ResearchGate - click "download pdf"), but it is not effective. 1.5 L of water will be quickly absorbed into the blood and will expand your blood volume, which will affect the release of various hormones, which will likely result in a loss of at least 0.5 L of water with the urine.

Rationale: If you are otherwise healthy and you urinate frequently (>6 day), you probably consume excessive amount of water in a day or too much at once.

You can learn from personal experience how much to drink to stay well hydrated (no dry mouth or dark yellow urine) and which frequency is suitable for you.