Sadly those pricey Rotopax storage containers are not waterproof ... not even close. To be fair Rotopax never claimed such on their website, but at $70 that is a little disappointing. Checkout the video below and see the results of various water tests on the Rotopax storage container, and how I was able to waterproof mine:

Rotopax Container

Locking Pack Mount

Foam Weatherstriping

D Channel Weatherstriping