What are the real benefits of drinking 2-3 litres of a water per day ? (If there are any)?

keeps you hydrated and helps your organs

None.

You just need to eat enough water for your body to work normally, without dehydration (typically that's more like 1-2 litres, except if you're been sweating a lot), but there is no point in going past that point.

Actually, drinking too much water can even *cause* dehydration, paradoxically, because you'ld pee all your electrolytes.

Water helps to flush out unwanted substances through urine, plays a great role in digestion, prevents constipation, aids in absorption, circulation, transportation of nutrients, clears your skin and is necessary in the creation of saliva and sweat to maintain body temperature

You get the ability to fly.