How do you use pressure to find leak?

Answer 1

If you are looking for a leak, and you can build up the pressure inside the thing, there are two ways you can find the leak pretty effectively. You can either submerge the object under water (if it won't damage the object), and look for bubbles rising through the water from the leak. This is very effective for finding leaks in inner tubes and tires, for instance.

If the object can't be submerged underwater for some reason, then apply a little soapy water to the areas that you suspect the leak to be. If you see soap bubbles growing, that is where the leak is!