Things You'll Need

Instructions

1

Put on swimming goggles that fit tightly against your face. Get into the pool and make sure the goggles don't take in any water. Other gear, such as snorkeling equipment, can help in your search for the leak, but they aren't as necessary as goggles.
2

Go down into the pool once you're sure the goggles give you a clear view. Starting at one side of the pool's bottom, look for a spot in the liner that is visibly torn or where bubbles come up through the vinyl, indicating that air is getting in. If you don't find a hole in the bottom of the vinyl liner, go along the sides of the pool to look for the leak. Pay special attention to the seams. This process can take a few hours, since you must constantly resurface for air, which is why diving equipment can come in handy if you know how to use it.
3

Test whether you've found the leak by squeezing a drop of food coloring into the pool in the location of the hole. The color will be sucked through the hole, if there is one.
4

Buy an underwater vinyl patching kit. An underwater kit prevents you from having to drain the entire swimming pool to repair the leak. You can find underwater vinyl patching kits at pool stores and home improvement stores.
5

Repair the leak in the pool liner with the patch kit. The kit comes complete with detailed instructions, which vary by manufacturer.