A water inspection is the truest way to identify a roof leak. To complete a water test, you will need a water hose, attic access, and a helping hand. You can begin your inspection by starting a video call or phone call. I prefer doing a video call because it allows both of you to know exactly what is going on at all times. After making a video call, have one person go into the attic above where the water stains are, and the other person go up on the roof with a running water hose. The person on the roof needs to be sure to start below the leak and work their way up the roof. If you were to start at the top of the area, the water would run down and hit all of the possible leaking areas. Ideally, start a couple of feet below where the leak is and hold the water in that area for a few minutes. Communicate with the person inside of the attic to see if any water is entering the attic. If none is found, move the water hose a foot or so upward and let the water run for a few minutes again. Keep completing these steps until eventually, the person in the attic acknowledges to you that water is entering into the attic. Once identified, remove the water away from the area until the leaking stops. To verify that you have found the leak, place the water hose back onto the area that you last identified water leaking into the attic. If your helper inside of the attic communicates back to you that water is entering again, you have identified the source of the leak. Your next step is to remove the shingles or flashings in that area and replace them. It is very likely that you will find rotten wood so be sure to have your decking, decking screws, saw, bar, hammer, felt, shingles, roofing nails, and flashings (if needed) ready to go before beginning repairs.