TruDesign Vented Loop – Composite Anti-Siphon Valve (Marine)

Protect your vessel from dangerous back-siphoning with the TruDesign Vented Loop—a critical marine anti-siphon valve designed to prevent water flowing back into your boat’s plumbing systems.

Designed and manufactured in New Zealand, this vented loop acts as a siphon break, stopping water from being drawn back through thru-hull fittings and into the vessel—one of the leading causes of accidental flooding.

At the core of the system is a silicone duckbill one-way valve, which allows air to enter the line when not in use, breaking any siphon effect. When fluid flows through the system, the valve seals tightly—even when particles are present—ensuring reliable performance in real-world marine conditions.

Constructed from glass-reinforced nylon composite, the TruDesign vented loop offers exceptional strength, durability, and resistance to corrosion and electrolysis, making it a superior alternative to traditional metal fittings.

The full-bore internal diameter design ensures unrestricted flow, maintaining system efficiency while providing maximum protection. Its integrated mounting feet allow for secure installation using three screws, making it quick and easy to install in tight spaces.

Available in multiple sizes (19mm, 25mm, 38mm), this vented loop is essential for maintaining safe and compliant marine plumbing systems.

Key Features

• Prevents back-siphoning & flooding – critical safety component
• Silicone duckbill valve – reliable one-way air entry, seals under flow
• Glass-reinforced nylon composite – strong, lightweight & corrosion-free
• Full internal diameter – no flow restriction
• Integrated mounting base – easy 3-screw installation
• UV & chemical resistant – built for harsh marine environments
• Wide temperature range (-40°C to +110°C)

Specifications

• Brand: TruDesign
• Product Type: Vented loop / anti-siphon valve
• Material: Glass-reinforced nylon composite
• Valve Type: Silicone duckbill one-way valve
• Sizes Available:
  • 19mm (¾″)
  • 25mm (1″)
  • 38mm (1½″)
• Temperature Range: -40°C to +110°C
• Mounting: Integrated 3-point fixing
• Use: Marine plumbing safety systems

Ideal Applications

• Marine toilet discharge systems
• Toilet inlet water lines
• Holding tank discharge lines
• Engine or generator cooling water intakes

Vented loops are essential because they break siphon action, preventing seawater from being drawn back into the boat—significantly reducing the risk of flooding.

Why Buy from Barton Marine NZ?

• Trusted NZ marine plumbing specialist
• Fast nationwide delivery
• Genuine TruDesign NZ-made fittings
• Essential safety component for NZ boating

Pro Tip 

For correct installation:

• Mount above the waterline at the highest point of the hose run
• Install vertically for proper valve operation
• Regularly check the duckbill valve for debris or wear
• Use double hose clamps for secure hose fixing