A hydrostatic test is a way in which leaks can be found in pressure vessels such as pipelines and plumbing. It is also the most common method often employed.

This method of testing should not be confused with the Hydrostatic Body Fat Test. This uses the principles of buoyancy to calculate a person's body fat. Hydrostatic tests, on the other hand, verify the performance of fluid pressure vessels. Using this test helps maintain safety standards and durability of a vessel over time. Newly manufactured pieces are initially qualified using the hydrostatic test. They are then continually re-qualified at regular intervals using the proof pressure test which is also called the modified hydrostatic test.

Hydrostatic testing is also a way in which a gas pressure vessel, such as a gas cylinder or a boiler, is checked for leaks or flaws. Testing is very important because such containers can explode if they fail when containing compressed gas.