Here in 2020, staying hydrated has become a cultural phenomenon. We make a big show about keeping water chilled in $40 water bottles, we use data to track and analyze how much water we drink, and Neptune-willing, we’ll soon be able to combine the two by optimizing the perfect temperature to drink water — you know, so as to get even more hydration from every drop.
At least, that’s what Reddit’s “Hydro Homies” would have you believe:
Generally speaking, the science is pretty all over the map on water temperature. Some studies say drinking cold water helps you lose weight. Others argue that drinking warm water is better because you “absorb more” of it. And a third camp has found that no specific temperature is “better” for you compared to whatever temperature you prefer and gets you to properly hydrate.
As for the specific claim that you ingest “more” water per gulp when water is chilled to exactly 39.2 degrees Fahrenheit, at first glance, it’s plausible enough. Assuming we’re under normal atmospheric pressures, the density of water at that temperature is 1 gram per milliliter. Meanwhile, for comparison, “Water around room temperature, 71.6 degrees, has a density of 0.9978 grams per milliliter,” explains Trevor Makal, associate professor of chemistry at University of Virginia’s College at Wise. “So immediately, we can see that per unit volume, one will certainly consume more water at 39.2 degrees than at 71.6, or any other temperature with a density lower than 1 gram per milliliter.”
That, though, only means so much. “Sure, water at 39.2 degrees technically packs more water into every gulp, but how much more?” Makal asks.
In order to find out, we can plug our aforementioned densities of water at 39.2 degrees and 71.6 degrees into the formula Density = Mass x Volume. Assuming the average volume of a “gulp” is 1 ounce, the “difference comes out to — wait for it… 0.066 grams,” Makal concludes. “And since one drop of water has a mass of around 0.05 grams, that means, per gulp, one drinks about one drop of water more by drinking water at 39.2 degrees as opposed to 71.6 degrees.”
Is one additional drop per gulp of water more water?
Technically, yes. But to say that those few extra drops will make any difference in your overall hydration is a bit tenuous (nevermind worth all the trouble of perfectly chilling your water in the first place).
And so, it must be said once more: The most beneficial temperature to drink water at is the temperature you prefer, or that which is immediately available to quench your thirst — much like your neanderthalic ancestor lapping up muddy water from the river in which he bathed.