What is Backflow in Plumbing?


Did you know that there is a potential for water to flow backward through your plumbing? This can happen when something blocks the natural flow of water and causes a pressure imbalance. In this blog post, we’ll cover the basics of backflow and teach you how to prevent backflow from happening.

What is backflow?

Backflow is a condition in which water flows in an unintentional direction while moving through plumbing pipes.

What causes backflow?

Backflow is caused by an unintentional change in the pressure of a water distribution system.

As water moves through the pipes in your home, friction between the water and the pipe walls causes the pressure in the system to drop. This drop in pressure is natural and is unrelated to backflow.

However, when there is a sudden change in pressure, such as when a fire hydrant is opened or a water main breaks, the pressure in the system can drop suddenly. This sudden change in pressure can cause water to flow backward in the pipes, contaminating your home’s water supply.

What are the types of backflow?

There are two main types of backflow: back pressure and back-siphonage.

  • Back pressure – Back pressure is a type of backflow where there is an increase in pressure in a downstream piping system. When the downstream pressure becomes greater than the supply pressure, backflow occurs. For example, if your boiler’s pressure relief valve is set too high, it can cause back pressure in your home’s piping system. The water from the boiler will flow backward, through the piping system, and into your home’s water supply.
  • Back siphonage – Back siphonage is a type of backflow that can occur when there is a drop in water pressure. If the water pressure in a water distribution system falls below the ambient pressure, backflow can occur. Back siphonage can happen if the main water line breaks or if there is a power outage. When this happens, the water in the pipes can start to flow backward, causing dirty water to flow into your home. Using too much water can also cause back siphonage. If you use too much water at once, it can lower the water pressure in the system, causing backflow.

What are common causes of backflow?

A few common causes of backflow are:

  • Water main break – A water main break can cause a sudden drop in water pressure, leading to backflow.
  • Power outage – A power outage can cause a pump to fail, leading to a drop in water pressure and backflow.
  • A clogged drain – If your drain is clogged, it can cause the water to back up and eventually overflow.
  • An obstruction downstream – This can be caused by anything that is blocking the flow of water, such as a broken pipe
  • An obstruction in the piping – This can be caused by anything that is blocking the flow of water, such as a build-up of sediment or a blockage.
  • Fire hydrant usage – When a fire hydrant is opened, it can cause a sudden drop in water pressure.

What are the consequences of backflow?

If left untreated, backflow can cause serious damage to your home. Backflow can contaminate your water supply, damage your plumbing system, and cause flooding. In some cases, backflow can even lead to structural damage to your home. Expenses associated with backflow can be costly, so it is important to take steps to prevent backflow from happening.

What should be done if backflow does occur?

If backflow does occur, the first step is to shut off the water supply to the home. This will prevent contaminated water from entering the plumbing system. Next, it is important to contact a licensed plumber or backflow specialist. They will be able to determine the cause of the backflow and take steps to fix the problem. In some cases, a simple repair may be all that is needed. However, in more serious cases, the entire backflow prevention system may need to be replaced.

How can backflow be prevented?

There are a few things you can do to prevent backflow:

  • Have a professional inspect your plumbing system regularly to ensure that it is in good working condition.
  • Install a backflow prevention device in your home.
  • Be sure to repair any leaks in your plumbing system as soon as possible.
  • If you experience a drop in water pressure, be sure to contact your local water provider.
  • If you have a clogged drain, be sure to clear it as soon as possible.

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