Gravity works towards the bilge. To add another through the hull, a second pump and wiring it to the panel would be redundant and unecessary. The purpose of the bilge is to have a low point in the boat so that water can be collected and then expelled by the bilge pump. Are you concerned about melted ice other spills? Melted ice is just fresh water, no problem. Other spills depending on their nature should be cleaned up and not washed down to the bilge. I have a rubber stopper that I place on the refrigerator drain so that the cold air does not escape down the drain. These will hold any water or spilled stuff until I'm ready to clean and drain to the bilge. Works for me.
