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Backflow Prevention And How It Works

All that you need to know about backflow prevention

Running water is one of the greatest inventions in history. Thousands of years ago, the Romans developed plumbing techniques and aqueduct systems to provide running water to their empire, many of which are still in use today.
Today, we have professionally designed plumbing and wastewater systems to provide our homes and businesses with fresh water for drinking and bathing.

While our modern plumbing systems are more advanced than the Roman aqueducts, they also have their own challenges to overcome. Instead of relying solely on gravity to move water like the Romans, we use pressure to move water through our pipes.
This modern reliance on pressure poses the risk of backflow.

Although you don’t hear about it often, backflow problems do occur from time to time.

In Australia, there have been several cases of injury, illness and even death due to the backflow of hazardous and toxic substances.

If you own a business, live in an apartment building or use an alternative water supply, you may need a backflow prevention system installed on your property.

backflow prevention

What is backflow?

Backflow is the unwanted flow of water from the property back into the water supply. Simply put, used water that may be contaminated flows back into our drinking water and could end up in someone’s glass.

This can happen when the water supply is interrupted due to nearby fire calls, repairs or breaks in the city main, etc. 

When the flow reverses or backs up, undesirable outside substances can enter the drinking water supply.
Examples include:

  • Swimming pool water flowing through a fill hose.
  • Chemicals from a car wash flowing back into the water system
  • Irrigation water fed with my treated water or pumped from a well or detention pond flowed back into the water distribution system through an illegal connection.
  • Grease traps failing and FOG contaminated water going into the sewage system

For this reason, state and federal laws require water utilities to identify all connections to the public water supply and establish a backflow prevention program. See the Sydney Water Backflow Prevention information

Causes of Backflow

Backflow occurs when contaminated water or other liquids flow back into the clean water supply.

The cause can be either:

  • Back siphonage, when water pressure suddenly drops, creating a vacuum or partial vacuum in the water supply lines and sucking contaminated water into the water supply; or
  • Backflow is when the water supply is directly connected to a higher-pressure device, such as a boiler or private well, forcing water into the supply system.

What are backflow preventors?

It is a device or mechanism that stops backflow from occurring.
For example, an air gap that either removes a cross-connection or creates a barrier to backflow is the basic way of backflow prevention.

A mechanical system isolator that creates a physical barrier to backflow serves as the fundamental mechanism for backflow prevention.

The main types of mechanical backflow preventers are. 

  • Pressure vacuum breaker (PVB) – the most common backflow prevention device. PVBs are easy to install and maintain, but they are known to discharge water occasionally and are not recommended for indoor use.
  • Double backflow preventers (DCVs) – are suitable for both indoor and underground installations. DCVs are slightly more expensive but are also very practical as they can be installed horizontally or vertically.
  • Reduced Pressure Zone Assembly (RPZ) – the most expensive backflow prevention option, RPZs are also the most reliable backflow preventers. They are safe to use with landscaping chemicals, making them ideal for use in irrigation systems.

A plumber licensed for backflow preventers or a qualified water management representative can tell you which device is best for your property.

Common methods of backflow prevention

  • Backflow prevention valves

To prevent backflow, plumbers use a variety of devices and techniques. One of the most common methods is the installation of backflow prevention valves. These specially designed valves installed in the water lines allow water to flow in only one direction. If there is a drop in pressure or a sudden change in water flow, the valve automatically closes, preventing backflow.

  • Installation of air gaps

Another method plumbers use to prevent backflow is the installation of air gaps. An air gap separates the water supply from potential contaminant sources. In order for the fixtures to be protected from flooding, the air gap must be at least one inch above flood level and at least twice as wide as the supply line. Air gaps are most commonly used in commercial and industrial areas where there is a higher risk of contamination.

  • Chemical treatments to prevent backflow

In addition to these mechanical devices, plumbers can also use chemical treatments to prevent backflow. Chlorine, for example, is commonly used to kill bacteria and other contaminants in the water supply. However, it is important to carefully monitor chlorine levels in the water, as too much chlorine can be harmful to human health.

backflow prevention

Dealing with backflows

If you find or suspect a backflow hazard in your home, contact an expert:

  • The building inspector in your community
  • A plumber

In addition to installing backflow prevention devices and using chemical agents, plumbers also play an important role in maintaining and testing these systems to ensure they function properly. This includes regularly inspecting the equipment and performing tests to ensure it functions properly.

The plumber must repair or replace the faulty appliance to prevent backflow if a problem is found.

The plumber’s role in backflow prevention is critical to the safety and purity of the drinking water supply.
By installing and maintaining backflow preventers, using chemical agents, and regularly testing and inspecting these systems, plumbers help protect our drinking water from contamination and keep our communities healthy.

What should you expect during a backflow preventer inspection?

Some states require annual inspections, so if you want to operate a business in one of these states, you need to comply with these regulations. That’s why it’s helpful to have a reliable inspection service provider you can call on every year.

During the inspection, the inspector will check the following backflow preventers:

  • Check valves
  • Main pressure device

The inspector’s goal is to correct any problems with your system’s pressure. Unbalanced pressure can cause the backflow preventer to malfunction. Therefore, regular inspections are critical to the continued function of your backflow preventer. There are various reasons why pressure can drop, highlighting the importance of annual inspections.

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Why inspections are necessary

If your backflow preventer is not functioning properly, the consequences can be catastrophic. As you may know, a backflow prevention protects your water supply.

It ensures that water can only flow in one direction.

If the device fails, backflow can occur. If this happens, water from the pipes will flow back into your water supply and contaminate it.

If an inspector finds problems, they will perform the above inspection and repair it using new backflow preventers and parts like the parts we offer here!

The right time to call a plumber

When it comes to your comfort, you shouldn’t let plumbing problems ruin your free time.
If you’re not sure if there are backflow problems in your home, call Plumbmaster Plumbing now to learn more.

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