Water does run downhill.
Install a sump pump.
Remove a few boards, dig a well beneat the deck, put the pump into the well. Run the hose out to wherever, and reinstall the boards (perhaps on a hinge for maintenance).
Water does run downhill.
Install a sump pump.
Remove a few boards, dig a well beneat the deck, put the pump into the well. Run the hose out to wherever, and reinstall the boards (perhaps on a hinge for maintenance).