Similar to the guy who sprayed up the drain pipe, I used to have a rig to blow line in electrical conduits that were full of water that used a piece of pipe and an air compressor (a BIG one) it would get all / everything out of the conduit. The piece of pipe was to get the string in and somewhere for the pressure to go if the conduit was broken. It was fun but messy to use.
Also a plastic grocery bag , as opposed to a 'rat' works way way better.