http://parkcityx.com/ff/kitchensink.jpg

I just found a leak under my kitchen sink, it was coming from the piece of hardware in my picture above that has the green arrow pointed at it. This is my cold water for my kitchen sink and I shut it off where I put the blue arrow.

What is this that piece called that the green arrow is pointed at?

The water was coming out of the small "spigot" of it. I am concerned because this piece almost looks like a pressure release or something. Should I be concerned that the water may be leaking prior to the valve I shut off as well (blue arrow)?

This leak had apparently been going at least a few days because the hardwood floor is showing signs up to 15 feet away (water not visible, must be leaking under floor).

I can't get a plumber here until tomorrow so I am just making sure I am know that this was the only leaking part.

Any thoughts?

Looks like ice-maker connection, you do have an auto ice-maker? Leak should have stopped with the angle valve closed(blue arrow). Should be quick fix for the plumber.

Thanks parttime! No, I don't have an ice-maker, there must have been one before. Thanks for the help, at least I know what it is now.

This is a self piercing valve which usually supply a fridge icemaker. If the valve is not being used, most likely the plumber will just replace the whole supply from the top of the shut off valve (blue arrow), to the fuacet, eliminating the leaking peircing valve. When the plumber is there, they will be able to determine if the shutoff valve is leaking and repaire as necessary. Good luck and please let us know the outcome.

Another name for it is a "saddle valve".

As every one says that this is a self piercing valve which usually supply a fridge icemaker, if you don't have that please see the image below and tell us where is it leaking from, you may be OK just by closing the valve, Thanks.

John

Update: the plumber replaced the whole supply. Apparently that ice-maker attachment was old school and probably not up to code anymore anyway. Now I just have to worry about the bamboo floor damage. Thanks for the help!