Chiming behind the lemming who said the water a few minutes prior going won't do anything. It certainly won't do absolutely anything no matter how much you drink. Once the bowel absorbs the water, adding more water to your body won't restore moisture to the stool.

What probably happened in your case is simply peristaltic movement, some people are more sensitive to it. So chugging a generous amount of water stimulates your gut tissues and encourages things to get moving along.

Going back to the water - of course if you stay hydrated and keep things hydrated it will help. But you cannot rehydrate a stool just by drinking.

The way I understand it is that your colon will work harder to reclaim water if you’re dehydrated, so staying hydrated will help keep stool softer overall. That said, rehydrating while constipated (or immediately before a bowel movement) won’t make a real difference since the water has already been absorbed from the stool and it can’t add it back.

I would imagine your drinking lots of water before, if you do it consistently, is probably just contributing to your overall hydration which makes it easier next time.

Just eat a handful of sugar-free gummy bears every morning before you leave for work and it will be so super easy to poop and clockwork regular.