There are many health issues related to water and wastewater systems of both residential and commercial structures. Backflow problems can result in serious consequences to the health of users of a plumbing system. A backflow valve is one plumbing component that is designed to prevent this problem.
Indoor plumbing fixtures such as bathroom and kitchen sinks, tubs and showers and toilets are required to have what is known as a trap in the system. This is usually an S-shaped pipe that is attached beneath the drain pipe. The trap is designed to literally trap a small amount of water after effluent water passes through the drain pipes, which acts as a barrier against backflow. Traps are dependent on the venting system to operate properly, and these systems connect drain pipes to the vent stack that is usually plumbed to gain access to the roof of a structure. Debris can collect in the vent cap outside, and this should be checked often and cleared of any debris.
The toilet presents the biggest hazard of cross-connection in indoor plumbing. All toilets must have certain components to prevent flushed water from backing up, bringing with it sewer gas and bacteria. One important component to prevent this is the ballcock. The air inlet of the ballcock must be installed above the water line in the toilet tank, so that the refill tube will not take in contaminated water. This can be prevented by adjusting the float arm to lower the water level of the tank.
Garden hoses are one of the biggest culprits for cross-connections. This problem occurs frequently when hoses are connected to sprayers that are used for washing cars or other items or when they are used to apply chemicals such as fertilizers, herbicides, and pesticides on lawns and gardens. Vacuum breakers installed at the hose bib can prevent backflow, but the internal parts can become defective after a time. This problem can be addressed by disconnecting the device from the bib, opening the housing and testing the spring inside to see whether it is moving freely. Debris can also collect in the housing, which collects on the spring and the O-rings. These items can be removed and cleaned. If they have become useless from wear or corrosion, they should be replaced.
Cross-connections in lawn-sprinkler systems can also occur, which has led to many states requiring certain types of backflow prevention devices to be installed in the water lines that feed these systems. The type of device used is often an anti-siphon valve, which prevents water from returning to the main water supply when sprinkler systems are inactive. Anti-siphon valves release a small amount of water occasionally as part of their normal function. Problems occur when blockage to the vent of the backflow valve occurs, such as from a rock or other debris. Removing this debris is relatively simple, and can be accomplished by using a small screwdriver or other similarly-shaped item to poke out the blockage from the seal. It is also important to install anti-siphon valves downstream of any other valves in the system.
- Photo Credit hosepipe and tap image by david hughes from Fotolia.com
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