I have lawn sprinkler system which is three years old. I discovered a leak via a wet area in the yard. After uncovering the PCV pipe it appears a compression fitting on the tie in to the main water line is leaking. There is not much room to work since the tie in is close to the main shut off to the sprinkler system. I have shut odd the water, cleaned the threads and tightened the fitting but still have a leak of about one drop per second. What is the next step? I have digital photos but do not know how to attach,'Thanks

Does this compression fitting have a ferrule? What type of piping material?

Just posted some pictures. Thanks

We don't see any pics. Did you start with GO ADVANCED from below the answer box?

Here are three pics of the water line and coupling.
Thanks

OK see them now. The system has a buffer and it took a few moments to post your pic. I am looking now.

If you unscrew that cap you will see an O ring or a ferrule, what do you see?

There is a metal ring which the main line slides into. I assume there is some type of "o" ring at the bottom of the fitting. I really cannot tell if the male fitting is cemented in or the blue stuff is some type of "dope". If I could unscrew then I could replace. If not then I'm not sure of the next step since the main shutoff and a zone control valve are really close.

The blue is pvc glue from the pipe to the male end of the fitting. If you can't get in there to fix it then cut it out and bridge the gap with rubber hosing like what is used to connect a sump pump.