Why doesn't my German anti-siphon spigot work with an American garden hose?

Question

This is maddening! I am stationed in Germany, and am just trying to water my lawn. The German stores have only plastic hose couplings that are the threaded-to-quick-disconnect variety (as are the sprinkler attachments and so on). The hoses are quite flimsy, and the water pressure will cause the fittings to come apart if I close the nozzle at the hose end when I am washing the car or something like that...so, I bought an American hose on base with standard brass threaded ends and a sprinkler for my lawn.

When I attach the hose and turn on the water, the anti-siphon valve (small hole in the bottom of the spigot) shoots out water. This happens when the other end of the hose has nothing attached, and water flows readily from the hose, so I would be surprised if it were a backpressure issue. The problem happens on two separate outdoor spigots...what am I missing?

Answer 1

Could it be the difference between American measure and Metric measure?  The hose seems to fit and s***w tight, but there could be even a millimeter difference which would cause a spray.  I'd first use some teflon tape and an extra washer.  Then...  

If water pressure is the problem, get a reducer.  The unit I have reduces the size from a half inch to a quarter inch.  They work much like the water savers we all use in our showers.