They are gregarious, and are found in small herds up to about 12 animals, although larger groups may aggregate in summer when grazing is more plentiful. The social organization consists of territorial males with breeding females, nursery herds and bachelor herds. The dominant male uses a definitive brand of body language to warn off other intruding males, including the 'proud' posture in which the bull stands very still and erect, holding his head and curved horns rigidly aloft. Waterbuck eat grasses, reeds and wildfruits, and in the dry season will browse on acacia.

They are roughage feeders, and are well-adapted to digest fibre. A single calf is born, usually in early or late summer. The calf finds its own hiding place in tall grass, and the female returns to suckle and clean it. At 3 - 4 weeks old the calf is able to follow its mother.