June 20, 2025
In the world of physical therapy billing, CPT code 97113 plays a unique role. It’s more than just a code; it represents a specialized form of treatment with clinical expertise. At Cures Medical Billing Services, we have worked closely with rehab clinics and physical therapists, helping them route the traces of billing for aquatic therapy.
So if you’re uncertain about when, why, or how to bill CPT code 97113, you’re in the right place, This guide draws on our firsthand knowledge and daily experience supporting practices like yours.
The 97113 CPT code stands for:
“Therapeutic process, 1 or extra areas, each 15 minutes; aquatic therapy with therapeutic movements.”
This time-based code is used when patients perform therapeutic exercises in the water. The water’s natural properties, flexibility, resistance, and hydrostatic pressure enhance movement, reduce stress on joints, and aid recovery. It’s a favorite among rehab specialists for conditions like arthritis, neurological disorders, obesity, and post-operative care.
From our experience with outpatient physical therapy clinics, we’ve seen aquatic therapy benefit patients with:
Water-based exercises like deep-water walking, leg lifts, arm resistance drills, and endurance movements are often easier for patients to perform with less pain and greater success.
To get reimbursed for 97113, insurance companies typically require:
Tip from our billing team: Payers are especially strict with aquatic therapy claims. Make sure your daily therapy notes link the exercises to improvement in function, strength, or ROM (range of motion).
Yes, CPT code 97113 requires therapy modifiers to indicate the type of outpatient therapy service:
Modifier | Use Case |
GP | Outpatient Physical Therapy |
GO | Outpatient Occupational Therapy |
GN | Outpatient Speech-Language Pathology |
CQ | Services provided in whole or in part by PTA |
CO | Services by Occupational Therapy Assistant |
Correct use of GP or CQ modifiers is critical for Medicare claims.
Only qualified healthcare professionals can bill 97113:
One of our clients, a multi-location rehab facility, improved approval rates by 30% after correctly adding CQ modifiers for assistant-led sessions.
Here’s what to keep in mind when coding 97113:
Code | Description |
97110 | Therapeutic exercises (land-based) |
Neuromuscular reeducation | |
97150 | Group therapy |
97113 | Aquatic therapy with exercises |
While 97110 and 97112 are common in standard rehab plans, the 97113 CPT code is preferred when water-based therapy is medically indicated.
“One client kept billing 97113 without the GP modifier and saw repeated denials. After a quick audit, we corrected the modifier usage and linked diagnosis codes like M62.81 (muscle weakness). Approval rates doubled the next month.”
Lead Billing Specialist, Cures MB
The CPT code 97113 isn’t just about billing; it reflects a therapeutic strategy that meets patients where they are, especially those who struggle with land-based exercises. Used properly, it not only enhances patient care but also ensures accurate and timely reimbursement.
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Use CPT code 97113 when therapeutic exercises are performed in water as part of a medically necessary treatment plan. If exercises are done on land (like using resistance bands or balance balls), then 97110 is the better code.
Yes, 97113 needs a therapy modifier based on the type of service. For example, use GP for outpatient physical therapy and CQ if services are performed in whole or part by a physical therapist assistant. Missing modifiers often lead to denials.
Since 97113 is time-based, you can bill one unit for every 15 minutes of direct treatment. Make sure you follow the CMS 8-minute rule and document the time spent, type of exercises, and patient progress in your therapy notes.
You must include a therapy diagnosis (e.g., limited mobility, muscle weakness), the clinical reason for aquatic therapy, details of the exercises performed, and total direct time spent. This supports medical necessity and justifies the use of 97113.
Coverage varies by payer. Medicare and many private insurers cover 97113 when it’s medically necessary and properly documented. If the therapy is viewed as wellness or not functionally improving the patient, it may be denied—so documentation is key.
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