Leaking RO Membrane Canister

[Joshua Jordan]

I recently purchased a second RO membrane for my RODI filter system. Everything is connected properly, but, for some reason there is a small dripping leak at the threads on the cap of the RO Membrane canister. Upon inspection I do not see an O-ring included. So I decided to wrap the threads with nylon plumbers tape. I did a few passes to make sure the threads were well covered but it still leaks. I have tried looking online for a RO membrane housing/canister o-ring with the thought that maybe I missed it or maybe it wasn't installed. But does anyone know if there is supposed to be an o-ring with this? If I can't find an o-ring or get it to stop leaking I may just buy a new one since they are so cheap. But just thought I would bounce this off of the group thinking that maybe someone has had this same issue. The red arrow points to where the leak is on the housing/canister.
Thanks so much.

 

[KStatefan]

Yes there is suppose to be an o-ring.

 

[Woodyman]

Amazon/online retailer, local hardware store, or home improvement store. If you go locally take the canister with you they should be able to help you find the correct size O ring.