Help with minor plumbing leak at fresh water connection

I would try some Teflon tape on the threads, a couple of wraps should do it. You can buy a roll in any hardware store. I would also tighten it a LITTLE tighter than finger tight.

You could also try pipe joint sealant on the threads.

Edit: When I first looked at the photo I thought I saw tapered threads, now I'm not so sure. I guess I would try a hose O ring as SWD suggested first.