I'm having bad hydration problems when i go out cycling, even over 2 hours?

most of the club tend to use 2 bottles over 3/4 hours but this is not enough for my can someone please inlighten me on what i should be doing to aviod a second round of hyponatremia.
i do drink a lot during the day as i need to as i do about 250 mlies on a bike a week.
10 answers 10