Can you fix most pool leaks without draining the pool?

Yes, you can – unless the leak is in the main drain line or the pool is a fiberglass shell needing structural repair. For vinyl liners, use an underwater patch kit; for concrete/gunite, use hydraulic cement or underwater epoxy. Draining is risky because liners can shrink and concrete can crack from hydrostatic pressure. Find the exact leak first with a dye test or listening device.