I'm working on installing a drinking water filter to my cold water line. The line that goes to the water filter is a plastic tube that's 3/8" in diameter.

Using a compression nut and compression ring, I connected it to my cold supply line which has a 3/8" male thread compression seat. When I turned on the water, the tube pops out from the connection and water was gushing everywhere (Good thing I was home when that happened!).

So my questions are:

Did I not tighten enough?
Am I using the proper components to connect a plastic tube to the cold water supply line?
Should I be using a plastic compression ring + metal insert instead?
Also... what would happen if I over tighen a compression fitting?

Thanks.

I'd say that you just did not have the compression nut tight enough. Try tightening some more but don't leave home until you're sure its working. Most of the filters I install come as a kit with all of the fittings, ice maker filter kits.

As Far As How Tight To Get It, Finger Tight And Then Take A Wrench Of Some Kind And Go Another Half Turn And Check It From There,
You Say It's a 3/8 Tube, Now There Are Id And Od, Inside And Outside Diameters. I Can't Say For Sure If That Is A Factor Here. Just Make Sure The Compression Fitting Slides Snuggly On The Tub, If There Is A Lot Of Side To Side Play Then Compression Washer Is To Big. It Should Be Snug.
And Id Also Think That The Fitting You Are Using Should Be Brass Not Plastic
When You Place The Compression Fitting On The Tub Slide It Up About A 1/2 And Let This Go Into The Fitting .
It Really Sounds Like You Just Didn't Get It Tight.

I just opened a kit that I'm going to install pretty much like your filter. Everything in the box was plastic. The nuts aren't even nuts, more like wing nuts so I'm hoping this cheap piece will work for me.

I don't think I've ran into that hardware