What is the best way to plug the water port on the seeder?

Today I ran into a problem where my UTM was dripping water straight into the seed bin. I want to prevent this from happening. Ideally, I’d purge the water line but I can’t do that unfortunately. The next best thing I can think of is to plug the water port on the seeder tool to stop any drops from simply falling from the water tube through the seeder.

Has anyone else plugged a tool port before?