I have a strong sewer odor coming from under my kitchen sink.

So far I have done the following:

I have made sure that the all pipes under the sink are clean, tight and not leaking.
I have made sure that the garbage disposal is clean, tight and not leaking.
I have made sure that the dishwasher drain pipe leading into the garbage disposal is clean, tight and not leaking.
I have cut a hole behing the sink/dishwasher and checked the vent pipe for leaks and everything looks dry.

One odd thing is I have a water hose outside near where the kitchen sink is. When I run the water I can smell the sewer smell, when I turn it off the smell goes away.

I am completely out of ideas as what to check. Please help!

We are having the same problem and two plumbers could not find the solution. Did you ever get your situation fixed? If so please tell me how!