Why is backflow bad?
Much like the veins and arteries that distribute blood all over the human body, your plumbing system is designed to keep water flowing in one direction. The water comes from any distribution system (deep well, water heater, main water line, etc.) and flows through any fixture (shower, tap, toilet, and so on). When water starts flowing in the opposite direction, then you are dealing with a backflow, which is a cause for concern because there’s a risk for contamination of potable water. This is the very reason why having a backflow prevention device is very important.
What causes backflow?
Changes in water pressure is one common reason why backflow occurs. Water pressure issues usually take place when is a sudden increase of water usage in the system, as what typically happens in municipal water systems when water lines are flushed or when firefighters are using the lines. Situations like these can create backpressure where downstream pressure is greater than supply pressure. Back-siphoning also happens when there’s a partial or full vacuum in your supply piping. These can cause a reversal in your water flow.
In residential water systems, backflow prevention is done through AVBs or atmospheric vacuum breakers. These are devices that allow air to enter the pipes to prevent siphoning conditions from happening. Other devices that prevent backflow are double-check valves, pressure vacuum breakers, and reduced pressure principle assemblies, though they’re found in industrial plumbing systems than residential systems.
Backflow prevention device types
The most common way to prevent water system backflow in residential water systems is the installation of atmospheric vacuum breakers, or AVBs. These devices work by allowing air to enter into a pipe to prevent siphon conditions from forming. Other devices include double-check valves, reduced pressure principle assemblies, and pressure vacuum breakers, all of which are most commonly used in commercial or industrial systems, although it’s not unheard of for home owners to get them installed for residential plumbing systems as well.
It’s important for your municipality to consider installing these backflow prevention devices because that will allow water pressure to remain constant even when there’s a sudden high volume usage.