New RO tube leaking at the quick connects
 

I had some (what I thought was) 1/4" polyethylene RO tubing from Home Depot. I noticed that it's slightly smaller in diameter than the tube that came with the unit. I put it on my RO unit and the quick connects are all leaking where this new tubing is used. They are fully inserted.

The tube has REHAU RAU-PE printed on it. It's white and translucent. I Googled it and found this...

https://www.rehau.com/download/14654...-rau-pe-en.pdf

Does anyone know if there are different standards or sizes?

There are O rings in those connections. If u use a smaller size tubing, as you found out, leaks occur.
Can you borrow a micrometer and measure? I would see if you could bring the tubing back. It most likely was sold to you as 1/4 inch. Can't be if all the fittings leak.
Are your old fittings all John Guest?

Sorry for the delay in responding. They are John Guest, yes, or at least that style.

I ended up cutting some tube already on the unit and using that instead. It stopped leaking. I just needed enough for an RO membrane flush kit.

It's funny Home Depot sells that stuff right next to the connections considering that they leak. Weird. I couldn't have been the only person with that problem.