Is there a way to fix a small water leak in a PVC pipe from inside the pipe?
I ended up pouring  some very liquid mix of waterproof cement down the pipe and catching it again at the exit, it seems that is filled the little cracks inside the pipe. It's been a few weeks of testing by pouring water down and I don't see any leaks anymore. I have to specify that the pipe was horizontal and the cracks on the bottom part of it, that allowed the cement to fill the cracks.