What are some ways to find a leak in a pipe?

Question

I have a leak somewhere under my sink in the kitchen. I have a number of junctions/pipe/hoses there (6 lines), and one of them has a leak. It doesn't happen all the time, only when there is back pressure (like when the garbage disposal runs), and not all the time then. I've checked everything, and there is no obvious location of the leak. The leak isn't a gusher, but it's not a drip either. I've spent a fair amount of time under the sink looking for the leak, but no luck.

When I have a leak in a tire, I can put it in water and watch for the bubbles. Is there a powder or substance that I can apply to the pipes and connections that will show a leak in a similar way? If not, any suggestions on finding the source of the problem?

Answer 1

This is the easiest way I know of to find them:

1) Dry off all pipes with a paper towel

2) Run the water, garbage disposal, spray hose, etc. - anything you think contributes to the leak

3) Take a dry piece of paper towel and wipe each joint and pipe. Inspect the paper towel after each one. When you find a spot thats wet, you've probably found your leak.

Answer 2

Fill the sink up and put some die or food color in then let it drain. Pick a color that will stand out and will be easy to find.