What is a Backflow Prevention Device and how often should it be tested? Trend Plumbing & Home Solutions are commercial plumbers offering Sunshine Coast Backflow Prevention Valve testing.
Backflow is when water flows backwards instead of in the way it is supposed to in a pipe or plumbing system. Backflow events happen when wastewater or other dangerous materials get into a potable/drinking water source. This can be caused by cross-connections that could let contaminants into the drinking water system. A backflow Prevention valve comes in various types which are installed on water services to prevent contaminated water enter potable water lines and ultimately being consumed and causing illness. As per Sunshine Coast Council, Is it essential that Backflow Prevention Valves are tested annually which is the property owner’s responsibility.
The type of backflow valve installed is dependant on the zoned hazard rating, which is determined by the installing plumber. Here are some common areas that backflow events can occur:
- Irrigation systems
- swimming pools
- Commercial air conditioning towers
- Bin or Vehicle wash down bays
- Commercial chemical injection areas
- Fire hose reels or Fire Mains
- Commercial and manufacturing processes.
What types of Backflow Prevention Devices do we service?
- Reduced Pressure Zone Devices (RPZD):
The RPZD is a testable, mechanical device installed at specific points in a plumbing system where there is a potential cross-connection between the potable water supply and sources of non-potable water or contaminants, this device is used in high risk areas whether possible contamination can cause death. It consists of a complex arrangement of check valves and relief valves, designed to ensure that water flows in one direction only. The check valves prevent the backflow of water, and the relief valves release any excess pressure build-up within the device to maintain its efficiency.
The importance of RPZDs lies in safeguarding public health and preventing waterborne diseases. When a cross-connection allows contaminants to enter the clean water supply, there is a risk of contamination with chemicals, pathogens, or other harmful substances. If these contaminants reach the drinking water system, they can pose severe health risks to consumers.
How does a RPZD work?
- During Normal Flow:
- During normal flow conditions, water flows in the intended direction, which is from the potable water supply towards the plumbing system. The first check valve, positioned upstream, allows water to pass through.
- The intermediate zone, located between the two check valves, is under constant pressure and has a lower pressure than the potable water supply but higher pressure than the downstream system.
- When there is a Backflow Occurrence:
- If a drop in water pressure occurs in the potable water supply (such as during a water main break or high demand period), the pressure in the intermediate zone remains higher than that of the supply pressure.
- In the event of backflow, the first check valve will close to prevent water from flowing backward into the potable water supply.
- Relief Valve Activation:
- If both check valves fail to close fully, and the pressure in the intermediate zone exceeds the supply pressure, the relief valve opens to discharge water to the atmosphere or to a drain.
- The opening of the relief valve prevents any backflow from occurring, as it provides an alternative path for water to escape, avoiding potential contamination of the clean water supply.
Trend Plumbing & Home Solutions offer regular testing and maintenance of RPZDs to ensure proper functioning valves for ongoing protection of the potable water supply.
- Double Check Valve (DCV):
A Double Check Valve (DCV) is a type of testable backflow prevention device used to protect potable water supplies from potential contamination caused by backflow. Double Check Valves are used on ‘Medium’ hazard zones where possible contamination can caused serious illness, typically installed on commercial plumbing services such as fire water lines, Fire Hose Reels, Irrigation etc. The clear different between a RPZD and a DCV is the fact that a DCV does not port water from the valve.
How does a DCV work?
- During Normal Flow:
- Under normal conditions, water flows in the intended direction, passing through the first check valve. This valve opens to allow water to move forward into the plumbing system.
- When there is Backflow Occurrence:
- If a drop in water pressure occurs or there is a reverse flow in the plumbing system, the first check valve will close to prevent water from flowing backward.
- Additional Protection:
- In case the first check valve fails to close fully, the second check valve, located downstream of the first, provides an additional layer of protection. It ensures that water does not flow backward into the potable water supply even if the first check valve malfunctions.
Single Check Valve (SCV):
A Single Check Valve (SCV) is a simple type of backflow prevention device used in Low Hazard zones to protect potable water supplies from potential contamination caused by backflow. Single Check Valves come in both non testable and testable variations that are normally found on Water mains and Fire mains on commercial properties. SCVs operates based on a basic design that includes a movable valve mechanism. It allows water to flow in one direction only, preventing backflow when the water pressure changes or when there is a reverse flow in the plumbing system.
How does a SCV work?
- During Normal Flow:
- Under normal flow conditions, water flows in the intended direction, which is from the potable water supply towards the plumbing system. The check valve remains open, allowing water to pass through with minimal resistance.
- When there is Backflow Occurrence:
- If there is a drop in water pressure in the potable water supply, such as during a water main break or high demand period, the check valve responds to the change in pressure. The valve automatically closes to prevent water from flowing backward into the potable water supply.
- Prevention of Contamination:
- By closing when the water pressure drops or when a reverse flow occurs, the Single Check Valve effectively blocks any potential contaminants or non-potable water from entering the clean water supply. This prevents the risk of contamination and protects the public health of consumers relying on the potable water system.
Regular testing and maintenance of Backflow Prevention Devices on the Sunshine Coast are essential to verify their proper functioning and ensure ongoing protection of the potable water supply. Trend Plumbing & home Solutions offer Sunshine Coast Backflow Testing and take care of all associated Sunshine Coast Council Paperwork.