Okay here is some background information: I used to water my chickens with multiple 5 (or so gallon) typical plastic waterers... However I quickly got tired of these for a number of reasons. 1) I had to fill them up every couple of days. 2) They are difficult to clean.... no matter what I do... algae grows on the inside of some... dirt accumulates inside... and I just got tired of scrubbing them out all the time. So... I hooked up a 35 gallon (recycled) food grade barrel to a small length of hose and ran this to an anti-siphoning, automatic waterer valve in a bucket. This is great because I could fill it with the hose... like once a week. Plus all you have to do is dump out and clean the bucket... the actual barrel doesn't get any contamination in it.... Then I thought to myself.. why even bother with the hose.. I just hooked a flexible pipe from the gutter of the hen house to the top of my barrel reservoir. Every rainstorm the barrels fill right up. Here is a couple pics of how I made this and my basic set-up http://www.swampyacresfarm.com/home/chickens/1-7-make-your-own-chicken-waterer Okay here comes the question part: 1) Does anyone see a problem with using rainwater to water the chickens. Again, the barrels are all screened so there are no mosquitoes...etc. 2) I have a BS in Cell Biology..... so I have some background... but not an expert in... microbiology... Anyway, I would say you would be hard pressed to "prove" that there would be more bacteria in a rainwater system versus a well system... provided they were designed properly. Even city water treated with Chlorine... would quickly become bacteria laden, while sitting in a plastic waterer with 25 chickens plucking away at it. Does anyone disagree with me on this? Interested to here any FACTUAL input. 3) Does anyone else use a rainwater system such as mine? Thanks for your thoughtful comments.