Sodium and carbs help the body absorb fluids. You can either buy such drinks ready or powder to add to water or stir 400–1000mg of sodium per litre of water (1g salt contains about 40mg sodium). Mixing fruit juice into water will also provide carbohydrates (fructose and glucose).
Be careful: Drinking an excessive amount of water is not good for the body, either.
Fun fact: Symptoms of drinking too much include nausea, vomiting, and headaches and can even cause what is called ’’water intoxication’’, brain damage and other severe issues, although that is very hard to reach and requires immense effort. I highly doubt that one could do that to himself.
Coffee, tea and other beverages help reach your daily fluid intake, too!