The waterbuck is a large, robust animal that has a shaggy brown-gray coat that emits a smelly, oily secretion thought to be for waterproofing. This neck hair is hollow which allows for extra buoyancy when swimming, helping them to keep their heads above water. Males are generally about 25 percent larger than the females. In East Africa, two types occur: the Common Waterbuck and the Defassa Waterbuck distinguished only by the white pattern on the rump. The Common Waterbuck has a characteristic white ring encircling a dark rump, while the Defassa has wide white patches on either side of the rump. If the Defassa and common waterbucks have bordering ranges, they often interbreed; as a result, some scientists consider the two groups as a single species.

The waterbuck is water-dependent and must remain close to a water source. However, this habitat furnishes waterbuck with a year-round source of food. Mainly grazers, they consume types of coarse grass seldom eaten by other grazing animals and occasionally browse leaves from certain trees and bushes. They feed in the mornings and at night and rest and ruminate the remainder of the time.

This is a gregarious antelope.  Only the males have horns, which are prominently ringed and long. The horns are widely spaced and curve gracefully back and up. Dominant bulls occupy territories which they defend by aggressive posturing and even fights.  Cows, calves and young bachelors congregate in herds.  The composition of such herds can vary daily as individuals freely leave or join these.  They are strong swimmers and when seriously threatened, will take refuge in deep water.

Calves are generally born throughout the year, although breeding becomes more seasonal in some areas, after which a single young is born. The mother hides her young for about three weeks, returning three to four times a day to suckle it. Each suckling session lasts only about five minutes, during which time the mother cleans the calf so that no odor is left to attract predators. Even so, there is a high rate of calf mortality.

Although the calves begin to eat grass when they are young, they are nursed for as long as 6 to 8 months of age.