to understand why it leaking at the bottom you need to undestand how the system works
water is produced and this water is pumped up to the draw. when the draw gets full it overflows and the water is returned to the pump chamber. then in time this chamber fills up and if the sensors dont stop it then it overflows
but surely you empty the water at the same time as cleaning the filter as running any dryer till its full is not a good idea
Dave