Flushometers

I had a similar idea as I'm building another bathroom in my house. I like the idea and they seem to work great in commercial applications. Yes, as I also found out, you need a 1 inch water line rather than 1/2 or 3/4 as would be more common. I considered adapting the existing 3/4 inch line to 1 inch however the question remains as to whether the volume of water through that smaller line will be sufficient for the vlushometer valve to function properly. Somewhere on the net (after Googling flushometer valves) I ran across posts by several different people who had tried it and had gotten unsatisfactory results. I pretty much gave up on the idea at that point.

flushometer toilets
the flushometer toilets are a great way to save money, but not neceserily in water. they are used in commercial installs because there is nothing to vandelize (mostly), and are somewhat reliable. They require super clean water that is at least 25 psi at 10 gallons per minuet (gpm). the inlet is 1", but you can get around that. If you were to up adapt the water line from 3/4" to 1" at the toilet, and have 40 psi or more pressure, then you should be fine. if not, you would have to install 1" pipe from your water source (the street connection or the well pump. BUT>>> these systems can get a clog in the diaphram and run constantly (and with a high pressure high volume connection, that is allot of water....) I recomend the standard toilet.