French term (edited): vivre d�amour et d�eau fra�che

I do think Ian's answer is the more common English expression, but if you want to keep the idea of water in there (since the bacteria are in a saline solution) then I think you can actually stick to a literal translation. It gets the same idea across and sounds idiomatic to my ear. I did find some uses of it as well:

http://www.baylor.edu/Lariat/news.php?action=story&story=111...
As a Spanish and philosophy major at the University of Texas, Haubegger never fathomed the dream she had as a 10-year-old girl of creating a magazine for Hispanic women would be realized so soon. After she graduated from Stanford Law School, she decided to attempt publishing after inspiration from one of her professors.
'Mr. Lazier really impressed on us that if you're going to become an entrepreneur then you should choose something that you're passionate about because **you are going to live on love and water** for the first few years,' Haubegger told a reporter for Texas Monthly.