We all know that approximately 70 percent of the human body comprises of water, present both inside and outside the cells. Our organs, muscles and even bones have high water content. Water is the essence of our existence but sometimes, our body holds on to too much of it. Such excessive fluid build-up in the body leads to water retention. Water retention or fluid retention (medically known as edema) is defined as an excessive build-up of fluid in the circulatory system, body tissues or cavities in the body which can lead to swelling of the hands, feet, ankles and legs. Water retention or edema can be triggered by a lot of different things.