One time I bicycled something over 40 miles in the hills outside Las Vegas on a 105-degree day. I:

    1. Drank a gallon of liquid (could have been water or sports drink, I don't remember) on that ~3 hour ride.
    2. Didn't pee until I got home -- and not much then.
    3. Came home with dry clothes, despite (obviously) sweating something like a gallon of liquid. There was no evidence of sweat, ever -- it all evaporated.

Reminds me of days of cycling across North Vietnam during the summer : 40c, tropical levels of humidity, very steep hills. I was young, stupid and stubborn.

One stop every 2 hours to chuck 500ml of beer (Bia Hanoi, pretty nice light blond), so about 4 stops a day. It worked fine ! Pee was ok color, enough tipsy to keep my sense but numb the pain of cycling. My clothes had aureola of salt and urea.

One time I was helping build a house in summer. I drank 5L of watery low-sugar tea apart from about 1,5L other liquids and peed maybe three times that day. I had dry clothes but very visible traces of salt on them. Other time I drank 7L of beer in a night, but peed like every 20min.

When I was a kid my mom stocked Minute Maid frozen orange juice and powdered vitamin c. When I was sick I would stay home (maybe 11 or 12, different times) and watch TV and drink orange juice. I would fall into a pattern of drinking a 10-12 oz glass of juice during a show segment (maybe 7 minutes) and during the commercial break I’d go pee and refill my juice. On the half hour break i’d make another pitcher. So that works out to something like 3 quarts of heavily-vitamin-c-dosed orange juice per hour for at least several hours out of the day. I have no idea how my kidneys kept up with that.

Ok, but that’s an extreme example and you only consumed 3.8L. 4.5L is a LOT. Even the 8 glasses a day of water suggestion is considered on the high side and that’s only 1.9L.

> Even the 8 glasses a day of water suggestion is considered on the high side and that’s only 1.9L.

The recommended amount depends on who does the recommendation but 1.9L doesn't seem high.

https://www.efsa.europa.eu/fr/efsajournal/pub/1459

"Adequate Intakes (AI) have been defined derived from a combination of observed intakes in population groups with desirable osmolarity values of urine and desirable water volumes per energy unit consumed. The reference values for total water intake include water from drinking water, beverages of all kind, and from food moisture and only apply to conditions of moderate environmental temperature and moderate physical activity levels (PAL 1.6). [...] Available data for adults permit the definition of AIs as 2.0 L/day (P 95 3.1 L) for females and 2.5 L/day (P95 4.0 L) for males."

https://apps.who.int/iris/handle/10665/43403

"The minimum water requirement for fluid replacement for a 70kg human in a temperate zone equates to 3L per day, or 42.9mL/kg [according to the Tropical Agriculture Association]. Minimum requirements for an individual the same size but in a tropical zone equates to 4.1 to 6L/day"

"Age and gender specific Adequate Intakes (AI) for water were established in 2004 by the [United States] Food and Nutrition Board (5). The Dietary Reference Intakes (DRI) for water are [for ages 19 and older] Men 3.7 L/day Women 2.7 L/day"