Body not getting hydrated even though you're drinking lots of water?

I drink lots of water everyday and even more when I exercise. But I seem to have a problem absorbing the water. Even if I drink 2 liters of water a day I still feel dehydrated. Did some research and realized it could be caused by having insufficient potassium in my diet. I started taking bananas on a regular basis and I no longer feel so dehydrated. Bananas are great for a quick snack too. Very healthy stuff with high potassium content. I have what we in Singapore call pisang mas, I have about 2 - 3 of them daily. And if you're not in the habit of eating breakfast like me, having a banana after brushing your teeth is a good way to get something in your stomach at the start of the day. I normally drink a glass of water after having a banana as I feel that the fibrous nature Of the banana will cause the banana to absorb that glass of water and you get a sort of slow release of water when the banana reaches your intestines. Better than the water just coursing through your intestines and your body desperately trying to absorb what it can while it rushes past in my opinion.