Quick Answer: The Communicating Vessels apparatus is a set of connected vessels open to the air, used to show that one liquid settles at the same level in all of them. The levels stay equal whatever the shape or size of each vessel.
Last updated: October 2026
Key Features
Vessels joined by a connecting passage and open to the atmosphere
Mounted on a base support
Filled from one vessel so the liquid flows into all the others
Coloured water makes the equal levels easy to compare
About This Product
Pouring water into one vessel and letting it settle shows the liquid reaching one horizontal level throughout, which leads to the idea that pressure in a liquid depends on depth and not on the shape of the container. Teachers link the result to water supply systems, level indicators, manometers and hydraulic systems.
Frequently Asked Questions
Why is the liquid level the same in every vessel?
At rest, pressure at the same depth in one connected liquid must be equal, so the same liquid stands at one horizontal level in all open vessels, whatever their shape.
