Somewhere along the way, "eight 8-ounce glasses a day" became gospel. It's a memorable rule with one problem: nobody can quite trace where it came from, and no major health body actually prescribes it. The honest answer to "how much water should I drink?" is the unsatisfying one — it depends — but it depends on things you can actually pin down.
What the commonly cited guidance says
The figures most often referenced in the U.S. come from the National Academy of Medicine, which estimated adequate daily total water intake at roughly 15.5 cups (3.7 liters) for men and 11.5 cups (2.7 liters) for women. Two catches people miss:
- That's total water — and around 20% of it typically arrives through food (fruit, vegetables, soup, even bread).
- It counts all beverages, not just plain water. Your morning coffee and lunchtime seltzer are in there too.
Strip out the food share and the drinking targets land closer to 9–13 cups (2.2–3.0 liters) a day for most adults — a range, not a number, because the right amount genuinely varies from person to person and day to day.
What moves your number up or down
- Body size. More body mass means more water to keep everything running. This is the biggest single factor, which is why sensible calculators start from your weight.
- Activity. Sweat is water leaving the building. Training days can add several extra cups versus desk days.
- Climate. Heat and humidity raise your losses even when you're not exercising; so do high altitude and aggressively dry indoor air.
- Pregnancy and breastfeeding. Both raise fluid needs meaningfully — breastfeeding especially, since milk is mostly water.
- What you're drinking. Not every drink hydrates equally. Most count nearly in full — yes, even coffee, in moderation — but alcohol works against you.
- Health conditions. Fevers and stomach bugs increase needs; some heart and kidney conditions require restricting fluids. This is where a calculator hands off to a doctor.
The two built-in gauges you already have
Bodies came with hydration indicators long before apps did. Thirst is the obvious one — reliable for most healthy adults, though it lags in older adults and during hard exercise. The other is urine color: pale straw suggests you're in good shape, while consistently dark yellow suggests you're running behind. Neither requires a subscription.
So why track at all?
Because the failure mode isn't ignorance — it's momentum. You know roughly what you need; you just get to 4pm and realize you've had one coffee and half a glass of water since breakfast. A tracker's job is to make your running total visible before the day gets away from you, and to make logging so quick you'll actually do it.
That's the entire design brief behind Quenched: your goal becomes a pool of water that rises as you drink, quick-add buttons log a glass in one tap, and gentle, pace-aware reminders only pipe up when you're genuinely falling behind the day.
How Quenched calculates your goal
When you set up Quenched, it builds a starting goal from the factors above — your weight, body profile (including pregnancy and breastfeeding options), activity level, and climate. It's a smart starting point rather than a prescription, and you can override it with a custom goal anytime in Settings, in ounces or milliliters. Many people tune it after a week or two of seeing their trends — that's the point of having the data.
A note that matters: none of this is medical advice. Always consult your doctor or a qualified healthcare professional for personalized hydration guidance — especially if you're pregnant, breastfeeding, managing a medical condition, or following fluid restrictions.
