Nests are usually made of dry moss. This shrew uses its big hind feet, fringed with short, stiff hairs, to paddle about under water. It can stay submerged about 15 seconds. Water cannot penetrate the shrew's dense pelage, so the animal itself never gets wet. A water shrew can run short distances across the water's surface, buoyed up by globules of air like a water bug.
Water shrews locate aquatic prey by touch.
Little is known about the breeding habits of this secretive species. The gestation period is about three weeks, with 4-8 young born from late February to June. Females probably bear more than one litter each year. Water shrews tend to be nocturnal but are also active at dusk, on cloudy days, and in the shade on sunny days. Longevity is about 18 months.