Sub-optimal hydration status is indicated by a urine specific gravity above 1.015, while a specific gravity of 1.020 technically signifies dehydration.

“what can you measure before you get dehydrated and it's actually under hydration or low water intake and the best way to measure that is a urine morning specific gravity um is one of the best ways to actually know if you've been consuming a good amount of water or not or in the evening you're in specific gravity and as long as you haven't had a lot of fluid within two hours of that task then it's going to be a good indication if you are consuming a good amount of water or a low amount of water”