The water shrews preferred habitat is aquatic and terrestrial and includes wet forest, streams and marshes.

The water shrew is particularly adapted to aquatic habits. It can live at least 2 miles away from water but usually inhabits stream banks in which it burrows extensively. Entrances are above or below water and tunnels are made narrow to squeeze water from the animals fur. The water shrew is solitary and active day and night throughout the year.

Water shrews swim fast, remaining submerged up to 20 seconds, hunting frogs, fish, snails, mollusks and insects, which it immobilizes with its venomous saliva. The shrew propels itself in the water with its fringed hind feet, using its keeled tail as a rudder. The water shrews ear passage is closed by two valves.

Breeding occurs in April through to September, with two or more litters of 3 – 8 young per season. Gestation is around 24 days. The offspring are weaned in about 37 days.