My only rationale for using the dinghy pump is that my 3 wet/dry vacs (small/med/lg) are all pretty nasty inside and I don't think I could ever clean any of them well enough, even with a new HEPA filter, to want to blow it into the fresh water lines. I have one-too-many as it is, and would be reluctant to buy a 4th just for this, even a cheap one. I have too much stuff -- my wife refers to our basement and garage as my "hardware store", but she's happy when something's not working and I have the solution.