I think the idea of filling the jug then pouring it into a milk bottle or similar us a good one. You'd know how many litres/parts thereof a new jug should hold. I use a plastic sports bottle which holds a litre though I don't drink much water during the night. I refill each day so the water is fresh.
If I took a jug of water to bed every night I'd never sleep I'd be back and forth to the loo even more than I am now. 1/3rd of a small glass does me so I can take a Melatonin if I can't sleep.
jj aren't you "looing" all night with that amount of water?