I have a ( what looks like 1/4 inch PVC poly tube that was tapped into my drain under the kitchen sink. It is a reverse osmosis water system. The fitting is corroded and broke. What would that fitting be called?

Hi Sc...

It sounds like you may be talking about a 1/4" male x 1/4" hose barb adapter (comes in brass or plastic)... see image below. These are available at all home improvement stores.

Is this what you wanted?

Mark

Yes that's probably it. Thanks