Which Plumbing Device Helps Prevent a Backflow?

Backflow in plumbing is a serious issue that may cause contamination of potable water. It happens when water flows contrary to the direction in which it is supposed to flow, and this may result in contaminating clean water sources with harmful substances such as chemicals, waste, or bacteria. Luckily, a number of plumbing devices have been developed to specifically avoid backflow to ensure that the water is flowing in one direction only, keeping your water supply safe and intact. In this guide, we will talk about the plumbing devices that aid in prevention of backflow.

What is Backflow?

Backflow is an undesirable reversal of water flow or other liquids into the public water supply or into a private plumbing system. This backflow is normally caused by water pressure changes. In the case of a decrease in pressure (as is the case with a water main break), the water may be forced back into the pipes and into the clean water supply.

There are two types of backflow:

Backsiphonage: This is the situation where the pressure of the water in a system is reduced, and the water is sucked back into the plumbing.

Backpressure: This occurs when the pressure of a system surpasses the pressure of the public water supply and water flows backwards.

Why Is Backflow a Problem?

Backflow may cause drinking water to be contaminated with harmful substances, e.g., sewage, pesticides, or chemicals. Such contaminants may be dangerous to health, and therefore, it is necessary to avoid backflow in plumbing systems. Plumbing systems should be fitted with the right backflow prevention devices to prevent these risks.

Plumbing Devices That Prevent Backflow

Backflow Preventer Valve (BPV)

One of the most common devices used to prevent backflow is a backflow preventer valve. It automatically switches off the water flow in case it senses that water is flowing in the reverse direction. The backflow preventer valve usually has two main elements, which are the check valves and shut-off valves.

How It Works:

- The valve will only permit the flow of water in one direction- to your home or facility.

- In case of backflow, the flow of water is automatically turned off by the valve to ensure that contaminants do not get into your plumbing system.

Types of Backflow Preventer Valves:

Double Check Valve Assembly (DCVA): This form of backflow preventer has two check valves which act in conjunction to stop water flowing backwards.

Reduced Pressure Zone (RPZ) Valve: RPZ valve is more sophisticated and offers more protection. It has a pressure relief valve that makes sure that the water does not flow back even when there is a high-pressure condition.

Check Valve

Check valve is a mechanical device that guarantees that water moves in a single direction. It is fitted at different locations within a plumbing system including the main water line or at the irrigation connections.

How It Works:

- The check valve is made up of a flap or disc which is opened by the movement of water in one direction.

- In case of reverse flow of water, the flap or the disc closes to avoid backflow and contamination.

- Check valves are usually used together with other backflow prevention devices to give extra protection against backflow in sensitive parts of the plumbing system.

Pressure Vacuum Breaker (PVB)

A pressure vacuum breaker is a backflow prevention device that is normally installed in irrigation systems or outdoor plumbing systems. It is a backflow preventer that is commonly installed in residential and commercial buildings.

How It Works:

- The PVB is made up of a valve that opens when the water pressure is normal and the water flows freely.

- When there is a sudden loss of pressure (as in the case of a water main break), the vacuum breaker opens and air enters the system, breaking the vacuum and eliminating backflow.

- Plumbing codes frequently specify using PVBs in irrigation systems to prevent contamination of the potable water supply.

Atmospheric Vacuum Breaker (AVB)

Atmospheric vacuum breaker is a very simple device used in residential plumbing systems to avoid backsiphonage. It is usually used in sprinkler systems or on hose-attached faucets.

How It Works:

- The AVB is fitted at the top of the plumbing system or the hose connection.

- The atmospheric vacuum breaker opens when the water pressure decreases, and it lets the air into the system and avoids the reverse flow, which may pollute the water.

- Although it works well in most situations, the AVB is inappropriate in high-pressure systems and does not eliminate backpressure.

Hydraulic Control Valves

In more complicated plumbing systems, e.g., in commercial or industrial applications, hydraulic control valves can be used to regulate water pressure and to make sure that water moves in the right direction.

How It Works:

- These valves automatically control the flow of water in order to keep the desired pressure and avoid backflow.

- They can be programmed to sense change in pressure and change the water flow.

- Hydraulic control valves are the best to prevent both backsiphonage and backpressure in systems where there is a need to control the water precisely.

Choosing the Right Backflow Prevention Device

The kind of backflow prevention device you use is based on a number of factors such as the kind of plumbing system, the possibility of contamination, and plumbing codes in the area.

Here are some things to consider:

Plumbing System Type

Residential: In the majority of residential plumbing systems, check valves, PVBs, and AVBs are typical devices used to avoid backflow.

Commercial/Industrial: Larger, more complex systems may necessitate the use of devices such as RPZ valves or hydraulic control valves to guard against backflow.

Risk of Contamination

Backflow preventers are essential to the plumbing system to avoid contaminating the potable water supply if your plumbing system is connected to an irrigation system, pool, or a system that utilizes chemicals or fertilizers.

Local Plumbing Codes

It is wise to consult the local plumbing codes because a lot of municipalities have their own requirements when it comes to backflow prevention devices. Depending on the risk of contamination, these codes usually require installation of these types of devices.