I recently purchased a new home and the faucet in the kitchen has something on it I can't figure out what it does. The faucet has one mixer handle and a plastic sprayer. To the right there is something that resembles a periscope.

It is about 1 1/2" in diameter with two small horizontal slits about 1/2" x 1" wide inside a silver metal cover that pulls off. I can remove the cover and there is a blue plastic piece mounted to the top of the sink with a removable plastic screw-on cover beneath it. Inside there is another smaller plastic hose piece cut at a 45 degree angle.

Under the sink there appears to be a 1/2" corrugated plastic hose that goes into the left side side wall and I can't tell where it goes from there. My dishwasher is installed to the left of the sink. I think the dishwasher and ice maker use a copper tube that runs along side the hose described above. (not sure)

Not sure if this is enough information but, I would be happy to send a digital photo if requested.

Thanks,