Leaking adapter

[Bommar2]

Im trying to install a reverse osmosis system and running into an issue with the faucet connection. The faucet included had a 1/4 thread, but the customer wanted a different faucet that has a 3/8 thread. The line from the RO system is a 1/4 plastic tube. So I bought this adapter from HD -3/8” to 1/4” lead free brass compression adapter. However, no matter what I do, the connection leaks. It seems to be leaking from the 3/8 faucet side. I don’t know if it’s just a bad product or what. I’ve tried thread tape and liquid thread paste with no luck. Is there a better product or something else I can try?

 

[Reach4]

Only use plastic to handle the RO water. RO water corrodes metal.

 

[Sponsor]

 

[WorthFlorida]

Plastic tubing with a nylon (or polyethylene) ferrule ring takes quite a lot of force to compress the ring around the tube. If you are using a plastic tube and a brass ferrule ring, you'll need a brass insert.

https://www.homedepot.com/p/Everbilt-1-4-in-Brass-Compression-Nuts-3-Pack-800929/207176809