Water retention is when the body accumulates too much water in the interstitial spaces of the tissues and is unable to get rid of it, such as through urination. Excess water can cause an area of the body to swell. The swelling is usually greater in areas below the heart. One of the most obvious features of water retention is edema of the lower extremities, especially the feet and ankles. The lower extremity edema may not be obvious, but it begins to show up a few hours after getting up and moving around, and it gets worse over time. If you press firmly on the ankle with your finger, a small dimple will immediately appear on the skin and it will take a longer period of time before it returns to normal. Medically, this phenomenon is called pitting edema, or generalized edema if edema is present in multiple parts of the body. Diagnostic criteria for water retention Edema can occur in many areas of the body, usually below the level of the heart, such as the buttocks, back, and even forearms. Edema in the legs can often be painful, especially when trying to walk. Severe edema may make it very difficult to put on shoes or socks. If the edema is very severe, the trapped water will begin to seep out through the skin, making the surface of the skin soggy. When the body begins to retain excess water, blood pressure usually increases, and this leads to many complications. The most common of these are congestive heart failure and pulmonary edema. Once pulmonary edema develops, the person will not receive enough oxygen and will experience shortness of breath, which can progress to coughing and other symptoms.