What is RDWC?
RDWC (Recirculating Deep Water Culture) is a hydroponic growing method where multiple plant buckets are connected with plumbing so water continuously circulates between them and a central reservoir.
Using properly sized bulkhead fittings for hydroponic systems and RDWC reservoirs is essential for maintaining consistent water flow and preventing leaks between connected containers.
Bulkhead fittings are used to create watertight pipe connections through the bucket walls, allowing water to move between containers without leaks.
Why Bulkhead Fittings Matter
In RDWC systems, each hydroponic bucket must connect to the others through PVC plumbing.
Bulkhead fittings create a sealed pass-through in the bucket wall so water can flow between containers without leaking.
A quality bulkhead fitting ensures:
• Leak-free connections
• Secure attachment to PVC plumbing
• Long-term durability in nutrient solutions
• Easy installation and maintenance
Before installing a bulkhead fitting in a RDWC container, the correct hole size must be drilled through the tank wall.
Bulkhead Installation Guide
Correct installation is critical to prevent leaks.
See the step-by-step guide below
Click to view the full installation instructions
What Size Bulkhead Fittings are for RDWC Systems?
1" Bulkhead Fittings
Best for small hobby systems or low flow designs.
1.5" Bulkhead Fittings
Good balance between flow and bucket wall space.
2" Bulkhead Fittings
Many RDWC growers prefer 2" bulkhead fittings because the larger diameter helps maintain strong water circulation between buckets.
The increased pipe size also helps reduce the risk of root clogging, which can occur when plant roots grow into smaller return lines.
Slip vs Thread Connections
Slip (Glue-In) Bulkheads
- Designed for PVC solvent cement
- Permanent connection
- Most common in RDWC builds
Threaded Bulkheads
- Accepts male threaded pipe or fittings
- Easier to disassemble
- Useful when plumbing may be modified later
FAQ
What size bulkhead is best for RDWC?
Most RDWC systems use 1.5" or 2" bulkhead fittings to improve water flow and reduce root clogging.
Can bulkhead fittings be installed in plastic buckets?
Yes. They are commonly installed in hydroponic buckets and reservoirs.
Are bulkhead fittings better than uniseals?
Bulkheads provide a rigid mechanical seal and easier plumbing connections.
Common Components for RDWC Hydroponics
