Is anyone doing Backflow Prevention Testing? If so, how much of a market is their for it?
How do you even go about that?
That’s another trade.
I think in Fl you need a plumber with another designation.
An RPZ (Reduced Pressure Zone) valve is designed for use in commercial and industrial applications to avoid back syphonage and pollution of the potable water distribution system.
To meet water regulations, RPZ valves are subject to an annual test by the local water authority which can only be carried out by an accredited tester.
http://zurn.com/operations/wilkins/pages/BackFlowPreventers/FAQ_BFP.htm
:)
I see no need for such an aux service as part of a home inspection.
I agree. 
In Florida we have them on residential properties also. It is required to have them tested and certified yearly. It is done by State Certified Backflow Technicians. Usually work with Plumbing Contractors and Utility Contractors. Residential certs go for about $35.00
From what I understand, anyone can be certified with some training, testing, and of course paying the Dep. of Health. I’m just not sure if it’s an untapped market or not.
Reece I think you need to ask some plumbers
In some jurisdictions, the Water District would test them to make sure they are functioning properly.
Reese, while some may seem to be discouraging your effort, if you can perform these inspections by aquiring the necessary qualifications and paying the fees associated with the certifications and make a profit go for it. I’d ck with the local jurisdiction to determine if you can get hired, who they are using and all that. But if it works for you well why not. By the way you look a lot like Carol O’Connor I miss that guy.
This inspection is required yearly up here by our water company. They can do it for $20 or you can have an outside certified firm do it for whatever they charge. 80% of the firms that do it up here are landscaping contractors that install sprinkler systems.