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.

The only way that I know of to repair this kind of damage without replacing the pipe is to have an epoxy lining installed.

What this essentially will do is add a tough epoxy coating to the entire pipe from the inside. This is something you would need a specialist for. The tools and materials are not readily available to a homeowner.

An epoxy liner is not 100% foolproof. There can be mistakes made with the application, and the existing pipe may continue to degrade and cause further leaks. The best way to fix this problem permanently would be to completely replace the new pipe.

Epoxy coating is a solution which requires professional help and expense and is better than the following "desperado" solution. Get in there and clean it thoroughly with hand made attachments. dry it properly with rags, paper fan etc. Scratch a groove on the crack or bad joint. Scratching is important. Allow to dry. Apply white silicon with a broom handle on which you have applied a chux wipe. This works for most INTERNAL PVC leaks where there is no external access. Shower drains, bath tub drains etc. I do not recommend pouring cement and catching it at other end.