One of the most common questions about kidney stones—and really one of the most common health questions in general—is what our daily allowance of water consumption should be. The traditional, folksy wisdom is that you should drink about 64 ounces (eight 8oz cups) of water a day—depending on your size, activity level, and temperature. The thing is there aren’t that many studies or evidence suggesting this to be the case. But, perhaps, an even better point is that there is no single metric for water consumption and overall health.
The most obvious metric, of course, is your hydration level. But here’s the thing: Being overhydrated can be just as dangerous—and potentially life-threatening—as being dehydrated. Moreover, one of the most reliable mechanisms in the entire body is our ability to detect dehydration through thirst. This is why there’s been promotional campaigns and educational videos to combat the myth that you need at least 64 ounces of water everyday—and that a much better strategy is to simply drink when you’re thirsty.
This rule-of-thumb to drink whenever you’re thirsty is an oversimplification as well—because your hydration level isn’t synonymous with overall health. We’ve always tended to think about drinking lots of water as a crutch for other unhealthy behaviors. Drink alcohol and/or coffee? Sit all day for work and thus don’t sweat out much of your body’s byproducts? Tons of people only drink when they’re thirsty, yet end up with a bright yellow color for urine that was formerly sitting in their bladder and kidneys. This indicates that plenty of uric acid had been sitting in your kidney stones and letting their mineral deposits settle to the bottom in the early formation of kidney stones.
This is why, it’s also common, in the context of kidney stones, to hear the recommendation of ten 10oz glasses of water each day to prevent kidney stones. With all this in mind, there’s a lot of technically true but misleading information. You’ve probably heard that you get a lot of your daily water from your food as well as other beverages. This is certainly true, but it’s not like drinking water is the same as drinking soda, juice, or beer. A nurse once told me that, more than just how much you drink, it’s what you drink. “Drinking is like doing your body’s laundry. If you drink Diet Coke, it’s like washing your laundry in Diet Coke.” Which is almost surely just as much metaphor as medical fact, but it also makes intuitive and anecdotal sense—and isn’t contradicted by any evidence or studies out there. And this is our best advice for drinking water and preventing kidney stones.