Plastic to plastic threaded fittings... use teflon or not?

On a boat's fresh water system I had to replace a threaded hose fitting. I put on teflon tape thinking it would help seal better but no matter how tight I screwed the fittings together I still get drips. Now I am wondering if w/ plastic to plastic threaded fitting connectors, is using teflon causing the problem? (Any other ideas why it'd still leak?--it cannot be further tightened)

One to two wraps max of tape is ok. Main cause of leakage on plastic threads is overtightening. Hand tight plus one/half to one full turn...that's it. You have proabably already distorted the threads.

quote; Hand tight plus one/half to one full turn...that's it.

I have never seen a plastic thread NOT leak if that procedure was followed. I tighten them until they are TIGHT, regardless of how many turns it takes.

Not using tape will not only allow leaks, but it can also "weld" the plastic together making disassembly almost impossible.

This type of thread is tapered and interference...to seal between the threads, you MUST use something, either tape or a pipe dope rated for use on the plastic pipe you have. Under an ideal world, 1/2-turn after finger tight MIGHT work, but don't count on it.