I don't worry about mine. I do as other suggest and I am just slightly careful when I wash it. I always wash it with one of adjustable garden hose nozzles with multiple settings. I find just the heavy mist one is plenty of water for the surface of the bike. I only use a bit higher pressure setting when I rinse under the fender and the to get all the brake dust out.
When I'm done with my chamois I grab a terri towel and gently wipe the surface of the filter, but that's more to pick up any oil residue than it is a worry about the water or water intrusion...
Then when I'm done with that I use that same towel to soak up the water that settle in that odd pocket underneath the rear jug on the primary side. I think that is important and everyone should do that. I don't want water standing in that area and messing up the finishes or causing any rust. I find that spot the one real oddity on the engine,