Gait training CPT codes: Complete guide to billing
Aquatic therapy CPT codes help physical therapists bill and document water-based treatment accurately, with CPT code 97113 as the primary code.
Aquatic therapy is an important treatment approach in physical therapy (PT) for a variety of patients, including postoperative patients, high-level athletes, and patients with chronic pain. The buoyancy, resistance, and temperature of aquatic therapy can reduce joint loading, improve movement patterns and tolerance, improve balance and gait, and allow patients to perform PT exercises with less pain. Aquatic therapy exercises can be adapted to a patient's mobility, balance, strength, and movement-tolerance goals.
Aquatic therapy is also a good option for high-level athletes who want less joint loading during long-distance training. It can also help patients with obesity exercise with less joint stress.
For physical therapists, effective aquatic therapy requires more than simply documenting that a patient “performed exercises in the pool.” The PT documentation must explain why aquatic therapy was medically necessary, how it supports a patient’s functional goals, and what skilled interventions were provided. Understanding the CPT codes for aquatic therapy also helps providers select the appropriate code for the services performed.
When to use CPT 97113 for aquatic therapy
The primary aquatic therapy CPT code is CPT 97113—aquatic therapy with therapeutic exercises. Under Medicare contractor policy, it covers skilled aquatic therapy that includes therapeutic exercise, neuromuscular reeducation, gait training, and other therapeutic movement in the water.
To bill aquatic therapy CPT code 97113, the clinician must document why exercise in water is clinically appropriate for that patient instead of on dry land. These requirements are important when selecting physical therapy CPT codes and supporting the medical necessity of treatment.
There are many reasons why aquatic therapy is performed, including:
Reduced weight-bearing tolerance
Pain that limits exercise tolerance
Balance and proprioception challenges
Reduced potential for falls
Gait and movement dysfunction
Targeted muscular weakness
Movement intolerance and deconditioning
Obesity and joint compression issues
Postoperative limitations and restrictions (active-assisted exercise)
What interventions are included in aquatic therapy?
Aquatic therapy encompasses a large number of interventions based on the needs of the patient. These interventions include:
Lower quarter
Gait training (reduction of load bearing)
Forward and backward walking and movement
Lateral activities
Step-ups (forward and lateral)
Lunges, squats, and functional movement
Ankle strengthening
Range of motion of hip, knee, and ankle (including active and active-assisted movement)
Upper quarter and spine
Core stabilization exercises
Scapular and cervical stabilization exercises
Upper extremity strengthening exercises (biceps curls, triceps activation, and more)
Functional upper quarter activity
Range of motion of the spine, shoulder, elbow, and hand (including active and active-assisted movement)
Full body
Balance and proprioception training
Preparation for return to land-based activities
Preparation for return to sport
Progression to independent movement
Functional activities
Cardiovascular training
Endurance training on an aquatic treadmill to reduce repetitive use strain
Which CPT codes can you bill alongside CPT 97113?
Under Medicare contractor policy, skilled exercise in the water is billed under CPT 97113 rather than under separate codes for each type of intervention. Other codes may apply to distinct services, such as land-based treatment, depending on the services provided and payer guidelines. Knowing the CPT codes for aquatic therapy helps you choose the code that reflects the skilled service the therapist actually performed.
These physical therapy CPT codes may apply to distinct services:
CPT 97110—Therapeutic exercise
CPT 97110 is one of several physical therapy CPT codes used for therapeutic exercise, while the aquatic therapy CPT code 97113 generally applies to therapeutic exercises performed in water as aquatic therapy under Medicare contractor policy. These exercises are focused on mobility, endurance, and strength, and can be performed in an array of movement practices.
It is important to note that when therapeutic exercises are performed in water as aquatic therapy exercises, CPT 97113 is generally the appropriate code under Medicare contractor policy. CPT 97110 may apply to distinct land-based exercises, subject to applicable coding and payer rules. Documentation should support any separately billed services.
CPT 97116—Gait training
CPT 97116 is used for gait training, covered in more detail in our guide to gait training CPT codes. Buoyancy reduces joint loading, improves balance, and supports proprioception, which makes the pool a useful setting for gait work. Under Medicare contractor policy, however, gait activities performed in water fall within CPT code 97113, the procedure code for aquatic therapy with therapeutic exercises. CPT 97116 may apply to distinct gait-training services performed outside the water, subject to applicable coding and payer rules.
CPT 97112—Neuromuscular reeducation
CPT 97112 is used for neuromuscular reeducation when the treatment is focused directly on areas such as motor control, biomechanics, balance, coordination, postural control, and proprioception.
When neuromuscular reeducation is performed in water as part of aquatic therapy exercises, Medicare contractor policy includes the service under the aquatic therapy CPT code 97113. CPT 97112 may apply to distinct services performed outside the water, subject to applicable coding and payer rules.
CPT 97530—Therapeutic activities
CPT 97530 is used for therapeutic activities focused on dynamic, functional activities that directly improve a patient's ability to perform specific movements. A functional activity performed in the pool does not automatically justify adding another code to 97113.
Under Medicare contractor policy, functional activities performed in water generally fall within the aquatic therapy CPT code 97113. Providers should not automatically bill CPT 97530 in addition to CPT 97113 for the same intervention. Any separately billed service must meet coding requirements and be supported by documentation.
CPT 97150—Group therapeutic procedures (to include group aquatic therapy)
CPT 97150 may be appropriate when therapeutic procedures are provided to two or more patients at the same time in a group, including group aquatic therapy, subject to coverage and billing rules. Medicare contractor policy points to CPT 97150, not 97113, for treating more than one patient at the same time in the pool.
It differs from individual, one-on-one treatment, so documentation should identify the group treatment techniques, number of participants, treatment goals, and frequency and duration of the sessions.
CPT 97036—Hydrotherapy
CPT 97036 is used for hydrotherapy involving a Hubbard tank, a specialized tank that uses agitated water to treat one or more areas of the body. This modality may be used to help relieve muscle spasms, improve circulation, or cleanse wounds and certain skin conditions.
Unlike the aquatic therapy CPT code 97113, CPT 97036 applies to a specific hydrotherapy modality. Medicare contractor policy does not allow billing a whirlpool (CPT 97022) in addition to CPT 97113, and other contractors may apply similar limits, so check your contractor's policy.
Documentation should support the medical necessity of the treatment and the areas being treated. Providers should verify applicable payer coverage and billing requirements before submitting claims.
How to document and bill CPT 97113
Medical necessity is the key to billing CPT 97113. The therapist must outline the reasons why aquatic therapy is an appropriate intervention for their patient’s specific needs and treatment goals, and document the rationale for using this aquatic therapy CPT code. Accurate documentation also supports the appropriate use of physical therapy CPT codes.
CPT code 97113 is a timed code billed in 15-minute units, and it is not limited to one unit per session. Only minutes of skilled exercise with direct, one-on-one contact between the therapist and patient count toward units. Time spent dressing, undressing, or getting in and out of the pool does not count. For Medicare, the 8-minute rule applies when calculating billable units:
0-7 minutes: 0 units
8-22 minutes: 1 unit
23-37 minutes: 2 units
38-52 minutes: 3 units
53-67 minutes: 4 units
These thresholds apply when calculating units for a single timed service, and each additional unit requires another 15 minutes.
When multiple timed services are provided on the same day, Medicare calculates total billable units using the combined qualifying treatment time.
Accurate documentation of the exact minutes spent on each service is essential in physical therapy, including aquatic therapy. Knowing when to bill CPT 97113 and how many units to bill supports appropriate billing and patient care.
Aquatic therapy helps patients improve mobility, increase safety, advance return to sport, and build balance and proprioception. Clear documentation of medical necessity, skilled interventions, and exact treatment time keeps your billing accurate and your claims supported.
Sources
Carayannopoulos, A. G., Han, A., & Burdenko, I. (2020). The benefits of combining water and land-based therapy. Journal of Exercise Rehabilitation.
Centers for Medicare & Medicaid Services. (2026). Billing and coding: Outpatient physical and occupational therapy services.
Centers for Medicare & Medicaid Services. (2026). Medicare claims processing manual, chapter 5: Part B outpatient rehabilitation and CORF/OPT services.
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