Get one of those Evian squeezy bottles and keep re-filling it and keep it with you ALL THE TIME!!! lol
Just the odd sip here and there will all add up but you do need it. I didn't have as much as i should have this morning and started feeling dizzy - i've had a couple of pints now and feel better. Keep on sipping!!
Think of it this way, when you're dashing to the loo every two minutes you're peeing away liquid fat!! lol