I went through something similar fairly recently. I carry a Fatboy Jumbo as an EDC. While swimming the dogs (I'm wading), the buckle on my strap came undone and the Fatboy plopped into the water.

Then, a week or two later the exact same thing happened at the same place! Talk about slow learner!

While my FAK is in a Pelican case, it highlighed that I hadn't been serious enough about waterproofing.

Now, I use a drybag as a liner for the main compartment.

Oh, and I'm going to put a bolt through that @#~@@ quick release buckle...

-john