The coat color of the water vole varies greatly with the subspecies, and its back coat is tan, gray-brown, and even black-brown. The base of the abdominal hair is iron gray, and the tips are khaki. The color of the side of the body is slightly lighter than the color of the back. Some subspecies have a brownish-yellow color, and some subspecies have no brownish-yellow color.

The tail and back of the water vole are of the same color, both dark brown, with a slightly grey underside of the tail, but it does not constitute a distinct dichroism between the back and the bottom. The back of the front and rear feet is dark brown. The top of the head is the same color as the back, the side of the head and the cheeks, sometimes including the ears, like the belly, with a dark brownish-yellow color.