I do the thing where you fill your mouth with water before swallowing too, just 'cause it's a bit more practical in some ways as I don't have to keep the glass up to my face, hehe. I do sort of swish my tongue in the water when I'm swallowing the several swallows it takes. I have big cheeks, hehe. Interesting that cows do that. I didn't know that. I've heard that you get quicker hydration from under your tongue and having the water in your mouth rather than swallowing it directly, so I suppose that's another reason it seems to work better to me. It was just sorta' natural for me.
I know what you mean about hot water out of a long hose. We used to live on some land that we were working on homesteading a long time ago in California in a place that only got 11" of rain a year at best so we did water conservation things and such too. In places like that you can usually heat the water quite well through passive solar methods like that. We used to put the water in 5 gallon glass bottles (used for drinking water dispensers) and put a roll of aluminum flashing partially around it so that it faced the sun. It would heat up the water quite well, especially when capped. We had a cork that fit them well that we put a pipe through that had threading that matched a low-flow showerhead that we put on the top/end of the pipe. It had an on/off switch for the water flow so we could take the whole thing and put it on top of a tower framework we had. It made a terrific shower.
We also used to have water in dark 50 gallon barrels that would heat up and we could take bath/saunas in (without soap) and then the grey water could be used to water things too. That was my favorite hot tub bath tub ever. My favorite bath tub ever was an area of a stream that had rocks that were a great tub shape and the water would rush in like a jacuzzi and out again, all naturally. It was not hot though, hehe, but not too cold either 'cause we're in Hawaii...
In hot dry places like that place in California or your place in Texas, wearing wet loose clothing really helps to cool you off, especially if there is any breeze at all. It's the concept that swamp coolers use. We had one of those that used solar power and was gravity fed the water into it. It was like an air conditioner in that climate.