[jnaas2]

A kitchen sink can be a long distance from the main line and if its clogged or partially clogged it can take a fair amount of water before it backs up. You say that you poured water into the drain and that it didnt back up but run the sink until it backs up and then take the drain apart and see if the water has filled the drain line up. The snake I use has a 100 foot cable on it and it can take 2 or 3 times before I can get them to open, Garbage disposals and soap scum can choke the drain down and make it very hard to get to flow without a powered drain machine