I purchased the Zodi Extreme in 2011. I have used it at least 150 times, maybe 200 since then. While I log a lot of my travel details, I don't keep a diary as to when I shower. Once every 4-5 days when camping is what usually happens.
I'm not sure what valve has broken for other people.
The little red handle for water ON/OFF seems a bit small and if a person is treating the unit roughly I could see that as a problem area, however, I take care on my possessions, so no trouble with that little red water ON/OFF valve, which has been operated probably 4x to 6x for each time I set up the Zodi Extreme.
See my build thread (soon, as Photobucket has yet to strike this album with the 3rd party hosting limitation) for the details on how I have the indoor portable shower working. You can wade through the entire build thread (actually two builds in the same camper, the thread has multiple pages, long messages on each page with lots of photos) or simply go to page 2, message #16 where the indoor portable shower description starts and ends at message #19.
Funny how ya wish you had something while out adventuring but when you get home it becomes out of mind or you decide that you did just fine without it - well, I've finally stopped procrastinating and ordered a Zodi Extreme. I went back and forth between the other great options peeps mentioned and decided that the Zodi just makes it so easy. Hope I can retro-fit a sink side sprayer without to much grief. Have a trip coming up this month to Cascade Locks,Sisters Wilderness and time permitting Owyhee Canyon- can't wait to try it out. Thanks to all for sharing your hot water ideas. And... Lardogsurf I hope this helps you out in your decision on your camper!!