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What is hydrotherapy and how does a hydrotherapy pool work?

man and woman relaxing in a bespoke stainless steel hydrotherapy pool

In this guide, we will be exploring hydrotherapy and the main benefits of hydrotherapy.  More specifically, we will be exploring what a hydrotherapy pool is and how it works. 

What is hydrotherapy?

Hydrotherapy is the use of water as a treatment and is widely used in rehabilitation to increase mobility in stiff joints, reduce pain, increase muscle strength and increase exercise tolerance.  Hydrotherapy is considered a type of naturopathic or alternative medicine as it makes use of the properties of water, rather than pharmaceutical interventions. 

Hydrotherapy, or water therapy, can encompass many of the properties of water including temperature, buoyancy, resistance and pressure. 

Hydrotherapy makes use of the pain relieving qualities of water alongside helpful exercises to increase the range of motion and relieve pain in the joints. It is scientifically proven to benefit both physical and emotional wellbeing. 

The use of water as a therapy is not a new concept, it has been used for thousands of years as a form of medicine and is now widely accepted as a form of physical therapy.  The definition of hydrotherapy can include any use of water as a therapy including steam, ice, showers and now also the added extras of salts and aromatherapy. 

Who is hydrotherapy for?

Traditionally, hydrotherapy has been targeted at those with certain conditions such as chronic pain, arthritis, injuries, recovery after surgery and those with neurological conditions.  Additionally, hydrotherapy has been a widely used treatment for professional athletes to speed up recovery and reduce DOMS (delayed onset muscle soreness). 

However, everyone could benefit from hydrotherapy because the health-promoting aspects of water have many benefits that go far beyond physical therapies.  

Why does hydrotherapy work?

Ever wondered why physical therapists might recommend hydrotherapy pools for injury recovery or strength training? It all boils down to the unique properties of water. Hydrotherapy pools provide a low-impact environment that's ideal for healing bodies. Here's how:


Firstly, water's buoyancy takes the pressure off your joints. Imagine trying to walk on land with a sore ankle – it's painful! In a hydrotherapy pool, the water supports your weight, allowing you to move more freely with less strain. This is perfect for early-stage injury rehab or for individuals with conditions that limit weight-bearing activity (and it also helps because it removes the fear of falling). 


Secondly, water resistance is your friend. As you move through the water, it provides gentle yet effective resistance. This can be used to build strength and improve range of motion and balance in a safe and controlled way. Therapists can tailor exercises to target specific muscle groups, making hydrotherapy a versatile tool for building strength, lengthening muscles and as part of a rehabilitation program.

Hydrostatic pressure

The hydrostatic pressure exerted by the water acts like a gentle massage, promoting blood circulation throughout your body. The heat in the water helps to dilate the blood vessels which further adds to improved circulation. 

This improved flow has a double benefit for injury recovery and strength training. First, it helps deliver oxygen and nutrients to your muscles, which are essential for healing, growth and boosting the body’s immune system. Second, it flushes away waste products like lactic acid, a major contributor to muscle soreness. This can reduce pain and stiffness, allowing you to recover faster and train harder during your hydrotherapy sessions.

The main benefits of hydrotherapy:

Physical benefits of hydrotherapy:

  • Reduce pain
  • Lengthen and strengthen muscles
  • Aid injury recovery
  • Supports physio and rehabilitation programs
  • Improve fitness and balance

Emotional and wellbeing benefits of hydrotherapy:

  • Workout recovery - improves cardiovascular exercise recovery (See source)
  • Strength training using resistance 
  • Stress & anxiety relief
  • Strengthened immune system - in particular with hot and cold contrast therapy

What is a hydrotherapy pool?

There are different types of hydrotherapy pools, each with features targeting different health benefits.  Usually, a hydrotherapy pool will be warmer than your average pool, kept at a temperature between 33 and 36ºc. Hydrotherapy pools will often feature massage jets or hydromassage beds to aid the therapeutic benefits, as well as water features such as waterfalls. 

Hot Tubs

A hot tub is probably the most well-known type of hydrotherapy pool.  Hot tubs feature heat, pumps and jets to allow the hot water to circulate around a bather. Hot tubs tend to be smaller and shallower than standard pools so are a popular option for those looking for regular hydrotherapy at home or in a smaller space. 

Resistance Swim Spas

A resistance swim spa is similar to a hot tub in that it features a heat, pump and jets within a seating area to circulate water.  However, resistance swim spas also have a counter current unit installed on one end to provide additional resistance for someone to swim against.  This gives the experience of swimming against a current, without the need for a huge pool.  Swim spas can still be much smaller than a standard swimming pool so are popular in residential settings or smaller spas. SpaFlo design and manufacture stainless steel resistance swim spas.

Cold Plunge Pools

Cold plunge pools are popular in hydrotherapy now as a form of cold water contrast therapy.  Using a sauna or hot water pool, the heat will dilate the blood vessels and a cold plunge will then constrict the blood vessels which improves circulation, reduces inflammation and reduces muscle soreness.  Alternating between hot and cold water treatments can help to heal injuries, speed up recovery and enhance bodily functions. 

Contrast therapy is often carried out alternating between a sauna or hot tub, and an ice bath or cold shower.  SpaFlo have created the UK’s first luxury hot and cold spa, the ContraSpa, featuring a hot side and a cold side to allow the user to alternate seamlessly between the two, without any delay. 

How does a hot water hydrotherapy pool work?

Warm-water hydrotherapy pools function like regular hot tubs or swimming pools but with a focus on therapeutic features. Here's a breakdown of the key components:

  • Pool Construction: They can be made from various materials like concrete, fibreglass, or stainless steel. The size and depth depend on the intended use, but they're typically shallower than recreational pools to allow easier standing and movement for therapy.  SpaFlo hydrotherapy pools are all manufactured using high quality AISI 316L stainless steel which is fit for both the commercial and private residential market.
  • Water Heating System: Maintaining a warm temperature (around 33-36°C) is crucial for therapeutic benefits. Water can be heated via air source heat pumps, heat exchangers, electric heaters or even a real fire.  Heat pumps ensure a consistent and comfortable temperature.
  • Filtration System: Just like any pool or hot tub, a filtration system is essential to keep the water clean and sanitary. This ensures a safe environment for therapeutic use.
  • Optional Features: Many hydrotherapy pools incorporate additional features for targeted therapy. These can include underwater treadmills, massage jets that create pressurised streams for muscle stimulation, mood lighting, counter current swimming units, and even adjustable floors for controlled water depth.

The word Spa is thought to originate from the Latin for ‘sanus per aquam’ which can translate as ‘health through water’. Central to the SpaFlo ethos, all hydrotherapy pools are bespoke builds, designed around the individual needs of each client.  Where the magic really lies is in the health promoting benefits of the water. 

“Having been involved in the design and installation of swimming pools and spas for over 20 years I have seen first-hand the healing power and benefits of water therapy, especially hydrotherapy.

Allowing water to take people's weight introduces bathers to a different aspect of exercise and movements that they may not be able to do out of water.  This often increases and improves flexibility out of the water, especially after repeated use.” comments Richard Gowland, Founder of SpaFlo Ltd.