And it does come down to your wee. I used to work in a hospital and they had pee charts on every ward.
Funny though...I was taken into hospital, NBM, very low BP so they had me on intravenous fluids. I was being told to drink as much as I can...blah blah...and then the lady came round with tea and coffee while I was drinking some lucozade. She asked if I should be drinking it and pointed to the board behind me which still had NBM written on it. Lucky I was ill and didn't notice I hadn't been fed or watered for 3 days!!