In New Zealand they have a 12.5mm pipe with push in fittings. You would think the half inch pipe might fit...., but no, it doesn't.
So here's how I have over come this problem...
Fortunately this plastic pipe is similar in size to copper half inch pipe and the compression fittings are available at most plumbing hardware stores.
First, use a dremel stone to slightly enlarge the hole in the center of the compression nut so that it slides over the plastic pipe. It only needs a "human hair" thickness taken off.
You can see that, in the photo to the right.
To the right is the fitting about to have the nut screwed on to make the compression. Once that is done, regular plumbing fittings can be attached.
o the nut.
Another method, show to the right is to get a hose tail with a plumbing threaded end, and attach with a suitable hose clip , or for a more secure fitting, use the wire tightener, and it's use can be viewed here.