[jncfhnb]

You don’t need much water. It doesn’t need to be that cool either. If you lack access to the water required to do this, which does not even need to be clean, then the lack of water is probably the bigger crisis.

Heatwaves and infrastructure failures can undoubtedly be serious threats. But the vast, vast majority of people survive wet bulb events when they encounter them.

[generic92034]

So you are saying a small amount of water would be enough to cool you down when it is (for example) 35° C at 90% humidity? How would that work? Evaporative cooling is out, for the most part and a small amount of water would be heated up to 35° C in no time.

[jncfhnb]

You just put your feet in the water and transfer heat to the water. It would not heat up to 35 in no time.

[sokoloff]

1 BTU is the amount of energy required to raise 1 pound of water by 1°F. Take 5 gallons (~42 pounds) at say 70°F (21°C). Raising that 42 pounds of water by 25°F/14°C will take just over 1K BTU.

That's maybe 2 hours of cooling per person and it's not at all obvious that during such a heat event that you'll have access to a continued source of 70°F/21°C water. If you only have access to 82°F/28°C water, 5 gallons only lasts you an hour or less.

[jncfhnb]

So let’s use your logic and ask how long could a person survive in a sauna?