Lisnhlin RV vacuum breaker check valve 571-VAC-CHK-A for B&B Model 571 — 1/2" NPT, prevents black tank flush backflow

Lisnhlin 571-VAC-CHK-A is a direct-replacement RV vacuum breaker check valve that prevents backflow into your freshwater supply and stops leaking black tank flush systems.

If your camper, travel trailer or motorhome has a leaking or failed check valve on the black tank flush line, the Lisnhlin 571-VAC-CHK-A offers a straightforward swap to restore one-way flow. Engineered to sit between the freshwater inlet and the flusher, this check valve keeps wastewater from siphoning back into clean water lines and reduces messy spills during flushing. It’s built for rugged RV use, tolerating typical water pressures and fitting standard plumbing threads for a quick install.

How does the Lisnhlin check valve stop backflow into my freshwater system?

The 571-VAC-CHK-A contains a one-way mechanism that allows fresh water to flow toward the black tank flusher but seals closed if pressures reverse. This prevents contaminated water from being drawn back into the freshwater line during siphoning events or when the flusher line is blocked.

• One-way check design prevents back-siphonage.
• Rated to handle typical RV water pressures (8–125 PSI).
• Sits between freshwater inlet and black tank flusher for direct protection.

Will this valve work with my RV’s existing plumbing and how easy is installation?

The valve uses 1/2" NPT male threads on both ends, matching common RV black tank flush fittings and making it compatible with many B&B Model 571-style systems. Installation is simple for anyone comfortable with basic RV plumbing: thread it into the line, ensure it’s installed at least six inches above the highest connected waste item, and check for leaks.

• Standard 1/2" NPT male threads for broad compatibility.
• Simple screw-in installation—minimal tools required.
• Installation height requirement: minimum 6 inches above the highest waste connection.

What durability and performance can I expect on the road?

Constructed for use in RV systems, the Lisnhlin check valve is engineered to endure normal campsite water pressures and routine use. It resists leaks and cracking that cause wet floors and smelly compartments, helping your black tank flushing system operate reliably over time.

• Designed for pressures from 8 to 125 PSI for reliable operation.
• Solid construction to replace cracked or failing OEM valves.
• Reduces the chance of contaminated water and messy leaks during flushing.

How will replacing the valve improve my black tank flush experience?

Swapping in a fresh 571-VAC-CHK-A restores proper one-way flow, preventing the common symptoms of a bad valve: backflow, blockages, and water on the camper floor. A working valve keeps the flush line functional and your freshwater separate from waste, saving time and cleanup after flushing.

• Stops leaks that soak the RV floor during flush cycles.
• Prevents contaminated water from reaching freshwater lines.
• Restores efficient flushing and reduces maintenance headaches.

Who is this for: RV owners, service technicians and DIYers who need a dependable replacement for a leaking or cracked vacuum breaker/check valve in black tank flush systems. It’s especially useful for campers using B&B Model 571-style flushers, travel trailers and motorhomes where one-way protection and easy installation are priorities. Choose the Lisnhlin 571-VAC-CHK-A when you want a simple, durable fix that brings your black tank flusher back to reliable service.