Depends who you talk to...some people say it's good for rehydration, others will tell you it shouldn't be consumed by humans...
I have just added some effervescent hydration tablets to my Amazon basket, will be here tomorrow, for today I have bought a 4 pack of sports drinks with added electrolytes
I agree about the glucose but think the coffee dehydrating is now less of a thing, the liquid taken onboard with the coffee more than outweighs any dehydrating effect..... Or so I'm happy to believe, possibly with a pinch of confirmation bias as coffee is my preference through the day.Be careful with the sports drinks. They usually contain loads of glucose for energy and caffeine and will actually dehydate you.
Drink water, cordial and the diaoralyte slowly ie a sip every few minutes. If you gulp it down it goes straight through your system without getting absorbed.
