Hi,
Water on the knee is a generic term used to describe
knee swelling which occurs when excess fluid accumulates in or around the
knee joint. There are many common causes for the swelling, including arthritis, injury to the ligaments or meniscus, or when fluid collects in the bursa. This condition is known as prepatellar bursitis.
The type of fluid that accumulates around the knee depends on the underlying disease, condition or type of traumatic injury that caused the excess fluid.