There is no single universal backflow prevention device symbol. On plumbing or hydraulic drawings, it usually appears inline on a water pipe as a valve or valve-assembly symbol, often with an abbreviation or equipment tag. The exact shape and label depend on the drawing convention, so always check the project legend.
Common notation
The symbol is schematic rather than a picture of the installed device.
- Double-check-valve assembly: may appear as two check-valve elements in series or as a generic inline assembly labelled DCV or DCVA.
- Reduced-pressure-zone device: may show two check elements with an intermediate relief zone or carry a label such as RPZ or RPZD.
- Other prevention methods: air gaps and vacuum breakers use different symbols.
These abbreviations are common project conventions, not universal definitions. Nearby pipe labels and line types provide context but cannot confirm the device type by themselves.
An installed assembly may have valve bodies, isolation valves, test points and connecting pipework. Do not expect it to look like the simplified plumbing plan symbol.
How to confirm the symbol
- Match the exact symbol, abbreviation and tag against the drawing legend.
- Trace the connected pipework and read nearby service labels.
- Cross-reference the tag with the hydraulic notes, equipment schedule and specification.
- Check that abbreviations such as RPZ, RPZD, DCV or DCVA are expressly defined in the drawing set.
Backflow prevention devices in NSW are governed by Australian standard AS/NZS 3500.1 (the national water supply standard, which prevents contaminated water or chemical hazards from backsiphoning into the community drinking mains). If drawing documents are missing, unclear or inconsistent, do not identify the device from its shape alone. Ask the hydraulic designer, building manager or a licensed plumber to check the current issued drawings. Fixed Today has provided trusted backflow prevention, annual testing, and compliance reporting across Sydney for over 15 years. If your site drawings are ambiguous or you need an on-site device audited, our licensed plumbers can verify the setup against your property’s specific hydraulic layout. Mentioning your property type and whether the valve serves commercial equipment, fire services, or domestic irrigation when you call helps our team arrive with the correct diagnostic gauges and certified test kits.