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Have you been experiencing some problems with your tap water recently? Chances are that the water travelling to your main may have become contaminated with pollutants like non-potable water or human waste. In such a situation, hiring a plumber and installing a backflow preventer is best.

You may have heard of the term 'backflow preventers’ but may not know their function and how they operate. Essentially, a backflow preventer is a device that ensures water flows only in one direction through a pipe. It prevents contaminated water or other substances from flowing backwards into the clean water supply.

There are different types of backflow preventers. One common type is the reduced pressure zone (RPZ) valve. An RPZ has two independent check valves with a pressure differential relief valve between them. If either check valve leaks, the relief valve discharges water into the atmosphere, preventing it from flowing back into the supply.

While backflow preventers are critical for protecting potable water supplies, it’s essential to have them installed correctly by a licensed plumber. Improper installation can create cross-connection hazards. Also, most backflow preventers require annual testing to verify they function correctly.

That’s why we’ve decided to share this brief guide here, explaining everything you need to know regarding backflow preventer systems. No special browser or internet device is required - just a desire to learn about this critical plumbing safety device.

Let’s begin, then! By the end of this article, you’ll understand what causes backflow, the different types of preventers available, and the importance of proper installation and maintenance. Protecting your drinking water is critical for health and safety.

What Does Backflow Mean?

Backflow Device Backyard

Most buildings in a city receive water from the main water supply line, which flows only in one direction. However, the water flow can be reversed in certain situations, such as during pressure changes in pipes.

When this happens, freshwater is contaminated with wastewater that contains bacteria, chemicals, and other harmful substances. This can often occur when a fire hydrant is opened, resulting in a loss of water pressure or a break in water mains.

Since no pressure pushes the water forward in such situations, it flows back to the city water supply. Dealing with problems caused by backflow is quite tricky and, not to deny, expensive.

That is why it is better to prevent them from occurring in the first place, which is where a backflow preventer comes in.

When Does Backflow Occur?

Backflow can occur in two situations that cause changes in water pressure:

Drinking Water Tap

1. Backpressure

This occurs when the pressure at your house is much stronger than the water supply. Because of this, harmful contaminants present in water can enter the water supply and reach other areas, such as the fire protection system or irrigation system.

2. Backsiphonage

Back siphonage occurs due to negative pressure in the water supply, which can cause dirty water and its contaminants to be sucked back into the supply system. Some situations that can cause this include breaks in the pipeline, use of undersized piping and withdrawal of water quickly.

What Is A Backflow Preventer?

A backflow prevention device is installed on pipes through which water travels only in one direction, and its function is to ensure that it does not flow backwards. There are several types of backflow preventers available for various purposes. The three most common types include check valves, vacuum cleaners and air gaps.

However, all three types of backflow preventers work to prevent the main water supply from getting contaminated. While businesses are required by law to get such devices installed, local legislation decides which homes require backflow preventers.

How Does A Backflow Prevention Device Work?

All backflow prevention devices are designed to prevent contaminated water from flowing back into the potable water system. However, how they accomplish this can vary depending on the type of device.

Person Testing Backflow Preventer

1. Check Valves

Backflow prevention devices installed on a fire protection system usually have two or one-way check valves. These are installed serially to prevent used water from backing into the potable water supply.

The two valves are the most crucial element, making up the double-check assembly, first used in the 1950s. Even if one valve fails or stops working, the other will ensure your property’s drinking water supply remains uncontaminated.

Additionally, in these types of backflow prevention assemblies, it is possible to close one backflow preventer valve to reduce the pressure differential and create a more effective seal. And the working of this system can be tested with the help of tiny ball valves or test cocks.

If the pressure on the side of your home exceeds the pressure at the city water supply, the check valves close, ensuring complete backflow prevention systems. The only drawback of this backflow prevention system is that both valves can always fail. Or debris in the water can prevent them from closing completely.

In such instances, there is a possibility of backflow occurring and contaminated water flowing back into the water main.

2. Vacuum Breakers

Atmospheric vacuum breakers (AVB) are usually installed in spigot, hose and faucet systems. They have a check valve connected to an air vent, opening when the system loses pressure. Upon opening, this valve allows air into the vacuum, sealing off the main water supply.

This backflow prevention device can prevent water from flowing back when there is reduced pressure. Vacuum breakers must be installed at least six inches above the ground for optimal functioning. However, they cannot block contaminants in the air from entering the water and are ineffective in plumbing systems with consistently high pressure.

3. Air Gaps

Most commonly used in sinks, air gaps prevent drinking water from getting contaminated by debris. They are best suited for homes where appliances like dishwashers are used and can help them last longer. This type of backflow prevention device creates an air gap between the flood level of the dishwasher and the water outlet.

Air gap backflow prevention devices are manufactured using various materials and can have different finishes. They are usually inexpensive and work by separating the hoses carrying fresh water and dirty water with the help of an air gap.

Dual inlet air gap devices are also available, which are ideal for connecting two dishwashers or a filtration system and a dishwasher. These are best for under-sink reverse osmosis systems and can prevent contaminated water from flooding your dishwasher.

Advantages Of Installing A Backflow Preventer

The biggest advantage of installing a backflow preventer is that it will prevent backflow into your home’s water supply and stop it from getting contaminated. Additionally, debris that may be present in contaminated water can damage your pipes, so this system will also keep the plumbing system protected.

Also, as mentioned before, the local water authority of your area may require you to install backflow prevention devices. That is why many new homes, especially those with sprinklers, come equipped with such devices.

And That’s How A Backflow Preventer Works!

Now that you know how a backflow prevention device works, installing one in your home is time. And the best way to do so is to hire a licensed plumber for the job. Licensed plumbers, like our team at WP Plumbing, possess the necessary expertise, tools and skills and can install such devices quickly and efficiently. Give us a call if you need a plumber in Melbourne!

Additionally, they can help you select the most suitable backflow prevention that meets the area’s legal requirements by inspecting the site. Remember to get your backflow preventer tested annually after installing it to ensure it functions properly.

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