Remove any access covers that hide your pool's plumbing system or pumps. This will make it easy to see water coming from the pipes.
Remove the filter media from your pool skimmer and other filters that you have set up. This will prevent the filter media from filtering out the pool dye.
Remove the cap from your pool dye and pour the dye into the water as close to the skimmer as possible. The skimmer will intake the dye and send it through the pipes in your plumbing system.
Inspect the pipes for the next several minutes and look for the dye leaking out from the pipes. Leaking dye is an indicator of a crack in a pipe.