As a stone former (kidney stones that is), is it wise to drink mineral water with low sodium levels instead of normal water? I find that mineral water does not complicate the digestive processes...
It doesn't matter if you choose mineral water with a low sodium content or regular tap water. What's more important is that you drink adequate fluids, around 2.5–3 litres per day, and keep your urine clear.
Drink fluid every hour or more frequently when exercising. An electrolyte drink may help you retain fluid and hence remain hydrated when exercising.
If you find it hard to fall asleep in the evening then have another glass of water. You might already have modified your diet depending on the composition of your stones, for example uric acid or calcium oxalate.