Some buddies and myself built an automated home brewing system for our senior design project in college last year, we really learned a lot. These projects are great, it's always interesting to see different takes on design and control.
I noticed that several of the rigs used copper and brass fittings. Since many of the components of beer are quite reactive, I'd be concerned about toxic copper salts forming. In addition to copper, brass and bronze fittings contain lead. The state of California has warnings about lead in brass and bronze even for your bathtub fixtures. There's also concerns about aluminum and plastics leaching. Most breweries use stainless steel throughout.
But then again, these toxins may pale compared to the mind numbing and beer belly creating effects that are the major achievements of drinking beer.