Hello Experts...

Amateur (very amateur!! ) plumber needing some advice:

Bought an old 2 1/2 storey house, and somebody ran some copper into the uninsulated side attic to feed the hot & cold water to a sink. This might not be a problem in California, but it sure is North of the border in Saskatchewan cold where it's 40 below a few months in the year.

Since we're renovating the bathroom professionally next year, I want to protect myself from freezing & bursting pipes... yet I still want to use the sink.

I've decided to run temporary lines inside the walls. The guy at home depot suggested that I just use flexible plastic rather than run 20 ft of copper and have solder several elbows as it would be much easier... I agreed.

I pot the flex and some plastic fittings... but then it struck me as odd to attach a plastic fitting to the old copper line... checked online, and I really haven't had much luck.

Any suggestions on how to connect my half inch flexible plastic to the copper line?

Your feed back would sincerely be appreciated... project is on hold until I hear from one of you wonderful experts.