Swimex Professional Blog

Hydrostatic Pressure Part 1

Hydrostatic pressure is defined on dictionary.com as:

A fluid at equilibrium at a given point within the fluid, due to the force of gravity.  Hydrostatic pressure increases in proportion to depth measured from the surface because of the increasing weight of a fluid exerting downward force from above.

That’s quite an involved definition. So I’m going to elaborate with pictures to make this important force a bit easier to understand.


hydrostatic pressure part 1This first picture demonstrates how hydrostatic pressure increases or decreases depending on how far a person or object is submerged in a fluid or more typically, in water.

Take a look at this man in the pool. His ankles (or given point according to the above definition) are submerged deeper in the water than his waist. Because his ankles are deeper in the water, there is more pressure exerted on them. Therefore, his ankles are experiencing a higher amount of hydrostatic pressure than his waist.  Conversely, his shoulders (or other body parts that are not as deep in the water) are experiencing less pressure.


A great property of hydrostatic pressure is that  it creates 3D pressure.  hydrostatic pressureCheck out picture 2. It demonstrates how the force of hydrostatic pressure comes in all directions. This is important, particularly in hydrotherapy, because of the support it provides all surface areas of a submerged body part.


A real life example of hydrostatic pressure is someone scuba diving or snorkeling.  If you have ever taken part in either one of these activities, you have undoubtedly noticed that the deeper you go underwater, the greater the pressure you feel in your ears. That is hydrostatic pressure! The deeper you go, the more pressure you feel!

Once you understand what hydrostatic pressure is, you can see how it has many attributes that can be used to aid and assist in hydrotherapy treatments and protocols. Watch for my next blog that goes into greater details about how to use hydrostatic pressure to when treating a client.

Read about the top benefits of hydrostatic pressure in Part 2 of this series.

swimex ankle sprain case study

Senior Physical Therapist at Brigham and Women’s Hospital specializing in biomechanics, orthopedic injuries, and aquatic therapy