Perhaps it would be a good idea to try to predict the future rate of "sips" from the faucet and donations to it, and automaticly preemptvelly reduce the amount each sip gets untill the funds and income get back to a more sustainable rate?
I checked it quite a few times (100 maybe) yesterday and the day before which is no means scientific but throughout the days it seemed to be trending up. Not just one or two huge donations but getting bumps. It seems that with it giving out .05 and a common donation being 1 to 5btc (20 to 100 times what they got) you only need a low % of people that take to give back. With how much of an impact it has on people I see them giving back more than not.
One possible option would be (if they wanted) to have it list recent or big donors, people dig that.
Honestly I think it will be fine though, obviously if the exchange rate changes scale it down, if you start giving out 50usd every dose then people are going to take the time to cheat it.