Key Points
- Both snakes have adapted to living in water and also bear a close resemblance to each other.
- However being able to tell them apart is crucial since cottonmouths are extremely dangerous while water snakes are harmless.
- The main difference lies in the shape of the head in the water moccasin vs water snake, which is large and square for the former, and flat and round for the latter.
Cottonmouth snakes, also known as water moccasins, are incredibly venomous. Their venom can kill a human, so itโs understandable that so many people fear themโand frequently confuse harmless water snakes for the cottonmouth. However, itโs important to know the difference between the water moccasin vs water snake for your own safety, as well as the safety of harmless water snakesโwho are often killed due to being confused with venomous cottonmouths! Letโs dive into what separates cottonmouth vs. water snakes!
Comparing Water Snake vs Cottonmouth

ยฉKF2017/Shutterstock.com
Water snakes, especially the northern water snake, can look very similar to cottonmouths. They are both dark in color, with darker markings along their bodies.
Water snakes may be banded like cottonmouths, or have patches that look similar to bands when observing them. Both water moccasin vs water snakes tend to stay close to fresh water sources and are found throughout the United States.
However, Cottonmouths do have some distinctive features which include a larger body and head, distinctive eyes, and pits on the sides of their faces.
Water snakes and cottonmouths look quite similar, possibly because theyโve both adapted to survive in the water. However, they are completely different snakesโeven belonging to different families.
In addition, itโs important to note that there are several species of water snakes, each slightly different in color and appearance.
These include:
- Northern Water Snake: This is the most common water snake found in the United States. At five feet in size, they are the most likely to be confused with Cottonmouths. They have dark splotches on their scales, which are easily mistaken for the dark bands of a Cottonmouth. If you cannot tell the difference, itโs always best to keep your distance from these snakes rather than risk yourself by getting closer.
- Southern Water Snake: Also known as banded water snakes, these snakes are found in the southern United States. They can be red, brown, or black in color, and are banded. Their coloration darkens as they grow older.
- Brown Water Snake: These snakes have light brown scales with darker patches. Their head is diamond-shaped. Brown water snakes are found in the Southeast of the United States and are often seen in trees, as well as in the water.
- Yellow-Bellied Water Snake: Just like the name suggests, these snakes have yellow undersides. The tops of their bodies are grey, green, or black. They live around the Gulf Coast.
- Red-Bellied Water Snake: These snakes are brown or grey with bright orange to red undersides. They are found on land more often than other water snake species.

ยฉsamray/Shutterstock.com
Water Snakeย | Cottonmouthย | |
Lifespan | Unknown wild lifespan; up to 9 years in captivity | Less than 10 years in the wild; sometimes over 20 years in captivity |
Head | Rounded, flat, sometimes has eye stripe | Large, square, always has eye stripe |
Bodyย | Long, thin body; no noticeable neck | Thick body with narrow neck |
Pupils | Round | Oval |
Pit | Does not have pit | Has pit |
The 5 key Differences Between Cottonmouths and Water Snakes
1.ย ย ย ย Cottonmouths have Large, Boxy Heads
Cottonmouth heads and necks are distinct from their bodies. While Cottonmouths have square heads, water snakes have rounded or flat heads that are not thicker than their bodies.
In addition, cottonmouths always have an eye stripe. Water snakes often have this feature as well, but not always.
2.ย ย ย ย Water Snakes are Thin with no Defined Neck
Water snake bodies are long and slender. Their head is not distinct from their body, so they have no defined neck.
Cottonmouths, on the other hand, are much thicker and heavier snakes. They also have big, blocky heads that stand apart from their bodies, creating a distinctive neck.

ยฉKatie Flenker/Shutterstock.com
3.ย ย ย ย Cottonmouths have Oval Pupils
Cottonmouths have oval, slit-like pupilsโsimilar to that of a cat. Water snakes have circular pupils.
It is also worth noting that the eyes of cottonmouth snakes cannot be seen when observing them from above.
Those of water snakes on the other hand are visible when you look down at their heads.
4.ย ย ย ย Water Snakes do not Have Pits
Cottonmouth snakes have pits on each side of their head, between their eyes and nostrils. These pits sense heat, allowing the snakes to detect and strike down prey.
Water snakes do not have these pits.
However, by the time you see if a snake has pits or not, youโre often too close for comfort! So, this isnโt a super reliable way for the common person to distinguish between these snakes.

ยฉSeth LaGrange/Shutterstock.com
5.ย ย ย ย Cottonmouths Live Longer
Lastly, letโs consider the longevity of a water moccasin vs water snake. Cottonmouths can live about twice as long as water snakes in captivity. Some cottonmouths have lived over 20 years, though their lifespan in the wild is much shorter.
Captive water snakes only live up to 9-10 years. Though we donโt know their average wild lifespan, we can guess that itโs similarly short. Animals rarely live longer lives in the wild than they do in captivity.
Up Nextโฆ
Keep reading these posts for more incredible information about key animal facts.
- 9 Non Poisonous Snakes in the World: They have a reputation for being especially venomous. But not all of them are. Read about 9 snakes with harmless fangs.
- 8 Fastest Snakes in the World: They can move fast and strike even faster. Discover the 8 snakes with the fastest draw of the jaw.
- How Long Can a Snake Go Withoutย Eating? Their carnivorous lifestyle is well known. But just how long can they go without a tasty morsel? Discover the answer in this post.
Discover the "Monster" Snake 5X Bigger than an Anaconda
Every day A-Z Animals sends out some of the most incredible facts in the world from our free newsletter. Want to discover the 10 most beautiful snakes in the world, a "snake island" where you're never more than 3 feet from danger, or a "monster" snake 5X larger than an anaconda? Then sign up right now and you'll start receiving our daily newsletter absolutely free.
More from A-Z Animals
The Featured Image

FAQs (Frequently Asked Questions)ย
What Should You do if Youโre Bitten by a Snake?
If youโre bitten by a snake, you should always seek medical care right awayโparticularly if youโre unsure whether or not the snake was venomous.
Even water snake bites should be watched for signs of infection such as swelling, discoloration, or failure to heal.
ย
Can a Cottonmouth Kill a Human?
Yes, Cottonmouth venom can kill a humanโbut itโs not likely. While itโs rare to be bitten by one of these snakes, itโs definitely not something you should risk!
If you are bitten, though, you shouldnโt panic. Thousands of people are bitten by venomous snakes every year in the United States, but only a handful end up dying from the bite.
Youโre more likely to experience symptoms such as pain, nausea, numbness, trouble breathing, poor vision, or an increased heart rate.
Will a Cottonmouth Snake Chase You?
If you encounter a wild cottonmouth (or any wild snake), you should calmly back away from the area. Cottonmouths donโt tend to be aggressive. Although they will lash out and bite in fear, they will not chase you.
ย
ย
Should I Kill Cottonmouth Snakes?
No, you should not try to kill Cottonmouths. Youโre much more likely to be bitten if you try to kill these snakes than if you simply leave them alone.
It may also be illegal to kill Cottonmouths in your state.
Do Water Snakes or Cottonmouths Make Good Pets?
No. Water snakes are very aggressive animals, despite lacking venom. Though Cottonmouths are less aggressive, their venom makes them dangerous to keep.
Thank you for reading! Have some feedback for us? Contact the AZ Animals editorial team.