2 litres is given as a recommended general amount; however, what is not known about that figure is that it is rounded up from a lesser figure and that includes water/fluid from all sources i.e. vegetables, fruit etc.
For those that workout, you may need more but you may not, overconsumption of water can also be an issue because it will dilute electrolytes, if you're not careful.
I honestly don't know how much I drink in a day but I'm hydrated enough, so it's not a problem...to see if you're hydrated is easy (apart from the urine colour test)...pinch the skin just behind the back of the wrist, if it returns to normal almost instantly, then you're hydrated, if it doesn't sink back to it's normal position and/or takes time to do so, you need more fluid.
Not peeing can be seen as being dehydrated, but when doing strenuous activities the body can shut off the urine trigger until such time as the body relaxes and then the urine trigger reengages and things are fine (it does have a medical name but I can't recall it, you can always look it up)...but some take this as dehydration and drink more which isn't the right thing to do and can cause serious issues. Even sports people and doctors can get it wrong, so the skin test is better at times.
36.5 kg /80.3 lb Middle-Finger DL (right hand)...