Aquatic therapy is one of the most frequently audited physical-medicine codes in rehabilitation. Why? Because insurers love the word therapy but hate ambiguity.
CPT 97113 (Aquatic therapy with therapeutic exercise) is a skilled, one-on-one therapeutic procedure — but it’s often billed as if it were a pool class.
Every year, compliance attorneys like Liles Parker LLP report recoupments where therapists billed for “therapy” that was, in reality, unskilled group exercise (Liles Parker, 2022).
Avoiding those errors isn’t about paranoia — it’s about precision.
Walking laps, floating with noodles, or running a pool fitness circuit is not aquatic therapy.
CMS explicitly states that aquatic therapy must include therapeutic exercise requiring the skills of a qualified therapist (CMS LCD L34241).
If the patient could perform the same task independently at a YMCA, it’s not billable as skilled therapy.
Fix it: Document how your professional judgment changed the activity — cueing gait pattern, adjusting resistance, or selecting depth based on pain and weight-bearing tolerance.
CPT 97113 is a timed, one-on-one code. If two patients are treated simultaneously, it becomes CPT 97150 (Group Therapeutic Procedures).
CMS audits routinely flag mismatched notes where therapists bill four units of 97113 while treating multiple patients in the same 30-minute block.
Fix it:
• Bill 97113 only for truly individual sessions.
• For shared sessions, use 97150 and describe the clinical rationale for the group format.
• In the documentation, clearly state “patient received 1:1 supervision throughout.”
“Because they like the pool” is not a defensible reason.
Each note must show why the water was essential — such as post-surgical pain, gravitational intolerance, or neuromuscular weakness.
Medicare reviewers expect a clear justification that land therapy would have been less safe or effective (APTA Documentation Standards, 2024).
Fix it: Begin every note with a “Rationale for aquatic environment” line. Example:
“Aquatic environment selected to allow early gait training at 50 % weight-bearing post-TKA.”
Auditors can smell identical notes across patients.
CMS considers repetitive documentation evidence of “lack of skilled intervention.”
Fix it:
• Customize each note with the patient’s unique goals, depth, and progression.
• Replace vague phrases (“good tolerance”) with objective data (“completed 3 × 10 hip extensions with moderate cueing”).
Automation saves time — but originality saves your license.
According to the Academy of Aquatic Physical Therapy, the treating therapist must be directly involved in the aquatic environment — either in the pool or at immediate poolside supervision (AquaticPT.org, 2024).
If a tech leads the session while you supervise from an office window, the service is not billable.
Fix it: Stay within arm’s reach or immediate line-of-sight. If using an assistant (PTA/OTA), document supervision type and your skilled input.
CPT 97113 uses 15-minute units. Round numbers like “30 minutes = 2 units” without start/stop times raise red flags.
Fix it:
• Record actual session times (e.g., 09:00–09:32 = 2 units).
• Align total time with documentation and billing log.
• Include brief statement of what occurred in each timed segment.
Payers want evidence that aquatic therapy is part of a continuum of care, not a permanent pool membership.
Fix it: Add a discharge or transition plan:
“Will progress to land-based strengthening once full WB tolerance > 75 %.”
That single line satisfies CMS’s expectation for cost-effectiveness and functional transfer.
• United Kingdom: NHS physiotherapists must document why hydrotherapy offers advantage over gym work, per the Chartered Society of Physiotherapy (CSP) guidelines (CSP.org.uk, 2024).
• Australia: Under the NDIS, aquatic sessions require outcome measures proving they address goals not achievable on land.
• Canada: Physiotherapists must indicate the functional limitation that justified the hydrotherapy session under provincial billing codes.
No matter the country, necessity + supervision + documentation = payment.
✔ Compliance Point Confirmed
Therapist present and licensed (PT/PTA/OT/OTA)
1:1 time documented in 15-minute units
Medical necessity stated in note
Exercise details and depth listed
Transition plan to land included
Signature and credentials on every note
Audits don’t destroy clinics — patterns do.
If every note shows clear reasoning, precise timing, and therapist presence, you’ll survive any payer review.
In aquatic therapy, compliance isn’t paperwork; it’s patient protection — and your best flotation device in a sea of auditors.
• Centers for Medicare & Medicaid Services. (2023). LCD L34241 – Aquatic Therapy. https://downloads.cms.gov/medicare-coverage-database/lcd_attachments/28992_17/ATHERSVCS.7_codeguide.htm
• Academy of Aquatic Physical Therapy. (2024). FAQ: Aquatic Physical Therapy Practice. https://aquaticpt.org/faq
• Liles Parker LLP. (2022). Enforcement Targeting Aquatic Therapy Providers and CPT 97113 Claims. https://www.lilesparker.com/2022/10/05/enforcement-targeting-aquatic-therapy-providers-and-cpt-code-97113-claims/
• American Physical Therapy Association. (2024). Documentation Best Practices. https://www.apta.org/your-practice/documentation
• TheraPlatform. (2024). CPT 97113 Guide for Clinicians. https://www.theraplatform.com/blog/958/cpt-code-97113
• Chartered Society of Physiotherapy. (2024). Hydrotherapy Guidance. https://www.csp.org.uk/documents/wphlag-guidance-provision-hydrotherapy
