After seeing a post regarding a super spendy aluminum on-the-roofrack shower system (that I was rather skeptical of) I took a look at my trusty solar shower bag. I love it, but it seems to have developed some agriculture inside. Not wanting to spend much, and now that it's warmer not needing the Zodi, I cast about for a solution.
I had one of these little (1.25g) pesticide-type sprayers; I got it at Harbor Freight for $10 and use it for spraying Star San in home brewing. Hmm.
http://www.harborfreight.com/1-1-4-quar ... 95692.html
I had the rattle-can paint out for another project, and quickly through a coat on the sprayer. On a warmish day I threw in just over a gallon (you need head space to pressurize if you're not gonna use gravity) and left it from 1 to 3:30, ambient air about 68F, water from tap 52F. It warmed up to 86F, not as much as I suspect the solar shower would but hey.
Shoots quite a stream, or very misty.
In a nice touch, you can lock on the spray. Or remove the sprayer alltogether. It pumps out probably a bit less than the solar shower in gravity mode, but much more if you pressurize it till the safety valve hisses. Also great for washing windshields, spraying annoying cats, washing the dog. Thinking of trying it as a beer dispenser, but might impart taste. And I'll probably shorten the wand a bit, although it is nice to direct a stream at the feet (one thing I don't like about the solar shower is that the water cools considerably as it falls to near your feet; less of a problem with this thing).
My other possible solution was to redirect the windshield washers; that used to be a fave when I was a teenager and cruising was still legal. But the washer fluid didn't warm up as much as I thought it would.