Definition of Aquatic Therapy: A therapeutic procedure which attempts to improve function through the application of aquatic therapeutic exercises. These procedures require constant attendance of a therapist educated in performing aquatic therapeutic exercises. [1, 2] Common synonyms: Aquatic Rehabilitation, Aqua Therapy, Pool Therapy, Water Therapy, Hydrotherapy (outside the USA). Note that aquatic therapy, as defined by the AMA, is not "tied" to a single profession. It can arguably be performed by several legally-regulated healthcare providers who have scopes of practice which permit them to perform such services and who are permitted to use the AMA's Current Procedural Codes (CPT). http://www.aquaticnet.com/qualifications.htm ©1997-2007, Aquaticnet.com
Aquatic therapy or pool therapy is physical therapy that is performed in the water. Aquatic therapy use the resistance of water instead of weights. It aims to rehabilitate patients after injury or those with chronic illness, avoiding the amount of weight placed on the joints by exercise outside the water.
The Aquatic Therapy Association of Chartered Physiotherapists defines aquatic physical therapy as: "A therapy programme utilising the properties of water, designed by a suitably qualified physiotherapist specifically for an individual to improve function, carried out by appropriately trained personnel, ideally in a purpose built, and suitably heated hydrotherapy pool" (ATACP, 2008). Also the South African Aquatic Physiotherapy Group (2009)  uses a definition which is very much alike: “Aquatic physiotherapy is physiotherapy which uses more than one of the unique properties of water for therapeutic rehabilitation”.
A Dutch definition, used in courses of the Dutch Centre of Allied Health Care (NPI) is: "Aquatic (Physical) Therapy is a programme, using mechanical and thermal characteristics of water during partial or complete immersion, in combination with the effects of movement. It evokes short-term and long-term adaptational mechanisms of a person with a deranged biological system, using specific stimuli to create biological and thus therapeutic effects."
Jenny Geytenbeek, author of the Aquatic Physiotherapy Evidence-Based Practice Guide (2008) , published by the National Aquatic Physiotherapy Group of the Australian Physiotherapy Association, gives the following definition and explanation: Aquatic Physiotherapy” refers to the special practice of physiotherapy, with therapeutic intent toward the rehabilitation or attainment of specific physical and functional goals of individuals using the medium of water. It differs from the more generic term “hydrotherapy” which connotes any water-based therapy conducted by an array of professional specialties, including immersion in warm water, immersion in mineralized water (balneotherapy and spa therapy), immersion in mechanically turbulent warm water (spa therapy), application of pressurized water to the external body (whirlpool), application of warm water into the colon (colonic irrigation), the application of water of various temperatures and pressures via showers and towels (Kneipp therapy), and movement-based therapy in water (hydrokinesiotherapy). “Aquatic therapy” similarly refers to water-based activity of therapeutic intent, is common among American literature, and includes the practice of e.g. physical therapists, exercise therapists, nurses and exercise instructors. “Aquatic exercise” has the intention of fitness training in both healthy and symptomatic individuals, and “water exercise” is its synonym."
Aquatic physical therapy can be applied at all three dimensions of the International Classification of Functioning, Disability and Health (World Health Organisation, 2001). A fourth dimension is Quality of Life, also an important goal in Aquatic Physical Therapy.
Aquatic physical therapy might also be supportive in treating some of the modern life-style conditions as well. A special issue of Physiotherapy Theory and Practice titled ‘Physiotherapy practice in the 21st century: a new evidence-informed paradigm and implications’, identified topics like nutrition and weight control, sustainability of physical activity and exercise, management of sleep disturbance and undue life stress. Evidence is still scarce, but issues like obesitas (Nagle 2007), adherence (Kang 2007), management of sleeping patterns (Vitorino 2006) and stress reduction (Bood 2009) have been addressed in aquatic literature, see also the chapter of the physiology of immersion and the autonomic nervous system.
Therapists who work in water typically seek aquatic therapy training as most physical therapy programs do not provide education in aquatic therapy techniques. Aquatic Therapy University  and the European Union Aquaevidence Network  provide therapists with post-graduate studies in aquatic therapy. In July 2010 the Board of the World Confederation of Physical Therapy (WCPT) approved the start of a formal network: Aquatic Physical Therapy International . This network provides opportunity to (physical) therapists to connect and share information. Objectives and activities are listed on the website.
Examples of aquatic therapy techniques include: Ai Chi, Aquatic PNF, the Bad Ragaz Ring Method , Fluid Moves, the Halliwick Concept , Swim Stroke Training and Modification, Task Type Training Approach and Watsu. The originators of each of these unique technique worked together with the Aquatic Resources Network  to craft operational definitions to aid in communication within the industry.
When available, an interview was done with the creator of the technique (Ai Chi, Fluid Moves, Watsu). When the creator was deceased, an agent of the organization charged with managing the technique was interviewed (Halliwick). When the technique was developed over time by the contributions of many individuals, the interview was done with an aquatic physical or occupational therapist who has published work on the technique in either a professional journal or textbook (Bad Ragaz Ring Method, Swim Stroke Modification and Training, Task-Type Training Approach).
This Operational Definitions of Aquatic Specialty Techniques  is available online to help understand each technique's nuances. NOTE: Aquatic Resources Network is currently remodeling their website to become a more news/research oriented resource for the industry."Aquatic Resources Network (Beta)". Retrieved 26 July 2012.
-  Musculoskeletal Interventions
Becker BA and Cole AJ, eds. Comprehensive Aquatic Therapy, 3rd edition. See