Originally Posted by eubank
Good question. Here I do a visual inspection of the device, making sure that the plastic one-way valve on the inside is not broken or stuck. Then I can hook one up to any faucet, turn the water on, turn it back off, and watch. A good backflow preventer will squirt water out the sides as the faucet tries to suck water back down; a bad one won't.
Appreciate your comments but it wasn't a question.
There are well defined requirements for different sanitary applications and risk levels. The difference between a testable and a non-testable device is well defined. Many jurisdictions only allow 'testable' backflow prevention devices in a medium and high risk application.
The hose bib antisiphon devices and check valves are rated as non-testable devices, which is why some places don't allow them as backflow preventers for flushing sewage tanks.
And since they are suitable in low risk situations, you can still buy them at your local hardware store. It's up to you, and your neighbors, to know when they can be used (like at the dump station) and when you shouldn't use them.
Otherwise, it's a crap shoot. Nothing worse then a good case of gastroenteritis when you're on a camping trip.