Changing a Chest Drain Bottle – Underwater seal drain (UWSD)
 
What an Underwater Seal Chest Drain Does: 

An underwater seal system is connected to a chest drain (tube in the chest) to collect fluid/air from the pleural space and prevent it from re-entering the chest. The water column acts as a one-way seal.  
 
When and Why It’s Changed 

Common reasons to change the bottle include: 
The bottle is approaching full (e.g., reaches a set volume threshold in local policy, commonly 1 litre).  
The bottle or tubing is damaged or leaking.  
Per local infection control policy (e.g., routine change interval).  
 
Step-by-Step Process (Typical Clinical Procedure) 

1. Prepare and explain 
Explain the procedure to the patient. 
Wash hands and put on appropriate PPE (sterile gloves, apron). 
Ensure good lighting and an uncluttered workspace.  

2. Prepare the new drain bottle 
Fill the replacement bottle with sterile water to the marked “zero” or required underwater level. 
Place the new bottle on a sterile drape or clean area ready for connection.  

3. Clamp or stop flow 
Prevent air or fluid backflow by either closing a three-way tap at the patient end or applying a clamp to the chest drain tubing. 
This isolates the system for safe change-over.  

4. Disconnect the old bottle 
With aseptic non-touch technique, disconnect the tubing from the old bottle — avoid touching sterile ends. 
Keep the open ends covered briefly if necessary.  

5. Attach the new bottle 
Connect the tubing securely to the replacement bottle’s inlet. 
Ensure connections are tight to avoid air leaks.  

6. Re-open flow 
Remove the clamp or re-open the three-way tap so drainage can resume into the new bottle. 
Check that the seal and tubing are functioning (e.g., bubbling/tidaling as appropriate).  

7. Secure and position 
Position the bottle below the patient’s chest level and upright (under gravity). 
Check tubing is not kinked or pulling on the patient.  

8. Document 
Record the date/time of change, volume previously collected, and initial reading of the new bottle. 
Note any patient observations before/during/after the change.  

9. Dispose of the old bottle safely 
Follow local infection control policies — often involve sealing the used bottle, double-bagging, and placing in clinical waste.  

10. Monitor the patient 
Observe for signs of respiratory distress, increased pain, changes in vital signs, or abnormal bubbling/leaks after the change. 
Document and escalate concerns per local policy.  

Key Safety Points 

Always maintain aseptic technique to reduce infection risk.  
Ensure correct water level for the effective underwater seal — too low can let air back in.  
Tubing and connections must be secure; loose connections risk air entry or loss of negative pressure.  
The system must stay below chest level/ hip height at all times to prevent fluid backflow.  
 
Note: 
This is a clinical procedure generally carried out by trained and competent nursing or medical staff familiar with chest drains, using local hospital protocols and infection control policies. It is not a self-care task for untrained individuals.  Ensure you receive supervision until deemed competent to undertake this task alone.