Peeps in extreme temperatures, plain water is NOT the only way to stay hydrated and can in fact be more dangerous if you're sweating a lot and not putting more electrolytes back into your body.
There are a ton of quick and cheap electrolyte drink recipes that you can find online. Tea, coffee, cocount water, milk, milk substitutes, juice, etc are all hydrating despite extremely persistent myths. Many fruits and veggies like cucumbers, watermelon, strawberries, bell peppers, etc have high water content and are a great way to hydrate while also getting vital nutrients. Popsicles are also a good way to stay cool and hydrated and you can buy them or make your own with whatever ingredients you want; there are recipes online, including ones for electrolyte popsicles, but you can also just do basic ones with your choice of fruit juice and whatever you want to add, like chunks of fresh or frozen fruit.
Anyone who is telling you that you can ONLY drink plain water to stay hydrated is incredibly misinformed, even if they have experience with high temperatures.
