I’m training for amarathon and get annoyed by having to stop to urinate during my training runs. I drink a lot the day before, and I drink about 8 ounces 45 minutes before I start. I then have to pee at mile 2, then mile 5. The urine is a light color. I’m tempted to not drink anything…
The kidneys need about 45 to 90 minutes to process liquid; nerves might hasten the process! Try drinking earlier, void the excess, and then tank up again. For example, if have a long run on Sunday at 8:00 am. Drink well the day before (stopping by 7:00 p.m, so you don't wake up 5 times during the night to go to the bathroom), then in the morning, have a good drink by 6:00-6:30. That should give you time to get rid of the excess water.
Alternatively, if drink well the day before and are well hydrated, you could drink 8 to 12 ounces right before you start the run, so the water will be in your system and not in your kidneys.
Experiment and learn what works best for your body!
For more information on fluids and hydration: