Wet and dry barrels are different styles of hydrants for different types of applications. The terms “wet” and “dry” indicate whether or not there’s water left in the barrel of the hydrant when it’s not in use—the part which is above ground.
Dry Barrel Hydrants
The barrel of the hydrant is drained or pumped dry when the hydrant is not in use and the shut-off valve is located underground. here’s no water left above ground after the hydrant has been used, so the hydrant is safe from freezing in cold regions.
Wet Barrel Hydrants
The shut-off valves are above ground, so there’s water in the barrel even when the hydrant is not in use. Each outlet has a valve that operates independently, and the mechanical parts are easy to access above ground and can be adjusted to the proper height without expensive modifications. This makes dry barrel hydrants an easy to operate and easy to maintain choice for warm climates where there is no danger of freezing.