Is the diamondback water snake venomous?

The diamondback water snake is harmless. Harmless. One of the most frequently killed snakes in the south purely because of the word 'diamondback' in its name.

How do you identify a diamondback water snake?

Dark markings form an open net or chain, not solid filled diamonds. No rattle and a tapering tail.

Where do diamondback water snakes live?

They are found in 14 US states, in habitats including water and wetland.

Diamondback Water Snake

Harmless

Nerodia rhombifer

The diamondback water snake is a heavy, rough-scaled snake of southern rivers and oxbows, and the name gets it into trouble — it is regularly reported as a diamondback rattlesnake despite living in water and having no rattle. The pattern is an open chain-link mesh, not the filled diamonds of a rattlesnake.

Venom: Harmless. One of the most frequently killed snakes in the south purely because of the word 'diamondback' in its name.
Adult length: 30–48 inches (76–122 cm)
Markings: A net-like chain of dark markings forming rough diamond outlines down a brown or olive back — an open lattice rather than solid shapes. The belly is yellow with dark half-moons.
Habitat: water, wetland
Family: colubrid
Range: 14 US states

How to identify a diamondback water snake

Dark markings form an open net or chain, not solid filled diamonds.
No rattle and a tapering tail.
Heavily keeled scales giving a very rough texture.
Almost always in or immediately beside water.

What it does when it sees you

Basks on branches over water in large numbers and drops in when disturbed. Musks and bites freely if handled.

What the diamondback water snake is confused with

One test settles each of these.

Western diamondback rattlesnake →

Rattlesnakes have a rattle, solid diamonds, and are not found swimming in rivers as a matter of routine.

Cottonmouth →

No white gape and no dark facial band; the pattern is a lattice rather than crossbands.

Where it lives

Alabama Arkansas Illinois Indiana Iowa Kansas Kentucky Louisiana Mississippi Missouri Nebraska Oklahoma Tennessee Texas

Before anything else

Back away and leave it alone. A snake that can see you leaving has no reason to bite. Most bites in the United States happen to people who picked up, cornered, or tried to kill a snake.
Never handle a snake to identify it. Every identification on this site can be made from a photo or from several feet away.
If someone is bitten, call emergency services now. Keep the limb still and below the heart, remove rings and watches, and go to hospital. Do not cut, suck, apply ice, or use a tourniquet — all of these make outcomes worse.
Do not try to catch the snake for identification. A photo from a distance is enough, and hospitals treat symptoms rather than species.

In the US, the Poison Help line is 1-800-222-1222. This site is a reference, not medical advice.

Not sure it was a diamondback water snake? Identify it step by step →