I usually don’t drink much water before or during a workout. During races, however, I hit the fluids at almost every aid station in almost every race.
Over time, I figured out the right balance of consuming water/fluid against your training. For most, getting it 80% right or better is really as simple as carrying a small water bottle with you, or running near ready access to water.
I think most runners over-think and over-do hydration. I think spending more than a sentence discussing hyponatremia is overkill (if you drink the electrolyte fluid available, you aren’t drinking a gallon of water per hour, and you eat a salty diet before the race, you’re fine). And I think a lot of the discussion online and in running groups is simply about upselling ‘hydration’ products you mostly don’t need.
And a lot of hydration related distress is beyond the control of your hydration: You either went too hard, it’s too hot outside, or both. No amount of hydration can prevent that scenario, and the best that effective hydration can do is partially mitigate the problem. What many think is a hydration problem is really a climate adjustment problem.
Still, I’ve figured out some effective principles that can keep you hydrated without sending you on needless trips to the restroom.