The treatment standards for rainwater typically come from local health departments - if there are national standards I've not been able to find them. For indoor non-potable use typically the rainwater is filtered prior to being put into the distribution system, which is often must be labeled as Non-Potable Rainwater. Many jurisdictions require signs "Non-potable - Do not drink"; I've seen these hung in the bathrooms above each toilet (regulations going too far, if you ask me). Disinfection is likely to be a requirement for indoor uses.
For outdoor irrigation, filtration is desirable to protect emitter heads from clogging. I've had jurisdictions require disinfection, although some don't require it for drip irrigation, only for spray irrigation.
cvg (Civil/Environme) 2 Apr 08 13:34
my dog drinks rainwater out of the gutter in the street all the time, prefers it to the clean stuff in his bowl...
Probably as it is not loaded with chemicals used in the treatment plants.
thanks to all,
We are in property development and support initiatives to conserve electricity and water. So in our current planning we are considering using rain water as "gray water" but so far still undecided on a system to use it.
dave.