The mm waterproof pump pack is a waste of money.
Try the aquapac. It's soft and you can push buttons right through it. It's kind of floppy but you can use a different belt or put the whole thing in a fanny pack. If just dirt is the broblem, there's Glad Press and Seal Wrap. I doubt it would keep water out if submersed but it should keep it clean.
DD age 10, dx at 4 (Oct 2006), Pumping with pink MM since July 2009, added Guardian February 2010. Podding over the summer since July 2012. Dex 4G January 2013. Also peanut allergic and asthmatic.
DS age 13, non-D, but peanut allergic and asthamtic too. Also Asperger's, ADHD, and a pinch of OCD.