Aquatic therapy/exercises
CPT code 97113 covers aquatic therapy—therapeutic exercises performed in a pool or water environment under professional supervision. This water-based treatment helps patients recover from injuries, surgery, or manage chronic conditions with reduced joint stress.
RVU breakdown
Conversion factor: 32.3465 · Source: CMS MPFS RVU25A · Confidence: High
Billing tips
Bill in 15-minute units only; 97113 is time-based and requires at least 8 minutes of direct one-on-one contact to bill one unit
Impact: Billing partial units incorrectly can trigger $36.55 denial per incorrect unit; use the 8-minute rule (8-22 min = 1 unit, 23-37 min = 2 units)
Document pool temperature, specific aquatic equipment used, and how water properties facilitated the therapeutic intervention beyond what could be achieved on land
Impact: Medical necessity denials account for 30-40% of 97113 rejections; specific documentation of why aquatic environment was required prevents downcoding to 97110
Never bill 97113 for group sessions or when the therapist is supervising multiple patients simultaneously in the pool
Impact: Group aquatic therapy should be billed as 97150 at lower reimbursement; incorrect coding of group as individual 97113 constitutes fraud risk and recoupment of overpayments
Verify facility registration with Medicare as aquatic therapy provider and ensure pool meets accessibility and safety requirements
Impact: Unregistered facilities may face 100% claim denials; retroactive denials can exceed $10,000+ for high-volume providers
Check for therapy caps early in calendar year and apply KX modifier proactively once threshold is approaching
Impact: Claims submitted without KX modifier after exceeding $2,230 threshold will auto-deny; resubmission delays payment by 30-45 days
Coordinate with referring physician to ensure aquatic therapy is specifically mentioned in the prescription or plan of care
Impact: Generic 'PT evaluation and treatment' orders without aquatic therapy specification increase denial risk by 25%; specific orders strengthen medical necessity defense
Common denials
Medical necessity not established—payer questions why aquatic therapy is required instead of standard land-based therapy
How to appeal: Submit appeal with comparative documentation showing patient's inability to perform exercises on land due to pain, weight-bearing restrictions, or safety concerns. Include physician notes supporting aquatic-specific prescription, patient's failed attempts at land-based therapy, and functional improvements achieved only in aquatic environment. Reference LCD L33642 or equivalent local coverage determination.
Denied as maintenance therapy rather than skilled rehabilitative treatment
How to appeal: Provide objective progress notes with measurable functional improvements (ROM measurements, gait speed, pain scale reductions, strength gains). Emphasize skilled intervention required for exercise modification, patient education, and progression. Cite Jimmo v. Sebelius settlement clarifying that maintenance therapy requiring skilled care is covered.
Insufficient documentation of direct one-on-one contact or constant attendance by therapist
How to appeal: Resubmit with detailed minute-by-minute treatment log showing continuous therapist-patient interaction. Clarify that therapist was in pool or at poolside providing hands-on assistance, manual techniques, or direct supervision throughout entire session. If billed in error for concurrent or group treatment, withdraw claim and rebill with appropriate code (97150).
Therapy cap exceeded without KX modifier or threshold exception documentation
How to appeal: Submit KX modifier attestation form with clinical justification for continued therapy beyond threshold. Include physician certification of medical necessity, comprehensive progress report showing continued improvement or prevention of deterioration, and specific goals not yet achieved. Request manual medical review if automated denial.
Frequently asked questions
What is the Medicare reimbursement rate for CPT 97113 in 2025?
The 2025 Medicare national average reimbursement for CPT 97113 is $36.55 for both facility and non-facility settings. This rate is based on 1.13 total RVUs multiplied by the 2025 conversion factor of 32.3465. Actual payment may vary by geographic locality based on the Medicare Administrative Contractor (MAC) adjustment factors.
How many units of 97113 can be billed per session?
The number of billable units for 97113 depends on total treatment time using the 8-minute rule: 8-22 minutes = 1 unit, 23-37 minutes = 2 units, 38-52 minutes = 3 units. Most payers limit reimbursement to 4 units (one hour) per session, though medical necessity may support longer sessions in exceptional cases. Each unit must involve direct one-on-one contact with constant therapist attendance.
Can CPT 97113 be billed on the same day as other physical therapy codes?
Yes, 97113 can be billed with other therapy codes (97110, 97112, 97116, 97140, etc.) on the same day if the services are distinct and separately identifiable. Use modifier 59 if required to indicate separate sessions or different treatment areas. Total treatment time must be clearly documented for each code, and combined therapy may trigger threshold reviews when approaching annual caps.
What documentation proves medical necessity for aquatic therapy versus land-based therapy?
Medical necessity documentation should include: specific diagnosis requiring reduced weight-bearing (post-surgical status, severe arthritis, obesity), evidence of excessive pain or inability to perform exercises on land, physician order specifically prescribing aquatic therapy, patient's weight-bearing or stability limitations, and clinical rationale for how water properties (buoyancy, hydrostatic pressure, warmth) facilitate therapeutic goals unachievable in standard gym environment.
Does CPT 97113 require the therapist to be in the water with the patient?
The therapist is not required to be in the pool with the patient, but must maintain constant attendance and direct one-on-one contact throughout the session. The therapist must be poolside or in the water providing hands-on assistance, manual techniques, verbal cueing, and immediate intervention as needed. Simply supervising a patient performing exercises independently does not meet the requirements for billing 97113.
What is the difference between CPT 97113 and 97150 for aquatic therapy?
CPT 97113 is for individual one-on-one aquatic therapy with constant therapist attendance, reimbursed at $36.55 per 15-minute unit. CPT 97150 is for group therapeutic procedures (including aquatic therapy) with 2 or more patients, reimbursed at a lower rate. Billing 97113 for group sessions is fraudulent. If treating multiple patients simultaneously in the pool, 97150 is the appropriate code.
Do I need special facility certification to bill CPT 97113?
While no special CPT-specific certification exists for 97113, the facility must meet applicable state regulations for aquatic therapy, including safety standards, accessibility requirements (ADA compliance), appropriate water temperature control, and emergency protocols. Medicare requires the performing provider to be licensed (PT, OT, or physician) and the facility to be enrolled as a Medicare provider. Some commercial payers require facility registration or credentialing for aquatic therapy services.