I have one, you need to prep it buy soaking it in boiling hot water. Then soak it in a bucket of water before each use.
Fill it up and hang off front bumper, by the time you get where you are going it has all leaked out.
From what I was told in the old days, people use to hang them in front of the radiator and the air moving through and around the wet bag would cool off the radiator.
Why boiling??? to set the canvas?...I soaked it for about 3 hours tonight and it holds water pretty well...few drips...figure you could fill it and have water in it for about 5 hours...
So who else is thinking of Jackson Browne?
http://www.allmusic.com/album/jackson-browne-mw0000193102
Or am I just showing my age here?
I still use mine:
Nice to get a cool drink of water on a hot day.
That bag looks almost new. In fact it probably IS new... They're still available from the original maker:
http://can-spec.com/canspec/products/products.php?ID=14
Here is another thread on the same subject. There is some interesting info on curing new bags. Also, check out the last post from me with a link to some interesting history on how they were used in logging.
http://www.expeditionportal.com/forum/threads/31950-Canvas-Water-Bags