Their urine usually has a whitish cast to it, but in this heat my girls are drinking lots of water, and by the evening, the stools will be solids in water. At least I know they aren't dehydrating.With this heat, I place large blocks of ice (size of Glad bowls) in the waterer morning and afternoon. If the water gets hot, I will see dryish poop and know to get them cool water.
Besides that, I always hold the bird out from me for the first minute or so until they poop, and then I place them in my lap for pets or inspections. My Roo would poop on me deliberately from the time he was 3 wks old until he was promoted to head roo. I swear he would strain until he made his mess. He was the only chick that did that.