@WillTell the limit sounds way too low imo (not only do you want more than 1 litre of water per day (iirc it was over 3 litres even), but if you don't actually eat and get water through solid food, you would want to intake more water by drinking than usual to compensate), but there is definitely reasons to not drink too much water.
I think the first you would notice is essentially dehydration without being dehydrated: the water essentially desalinates you, producing similar symptoms. While not quite the reason, this is kinda the reason why sports drinks are not pure water: we need salts to actually absorb the water well, etc. et al. And sweating/urinating/stuff steals stuff alongside the water too, which needs to be replenished.