What is Backflow?

By: Tom Hartel

Backflow Is:

The undesirable reversal of flow of water or mixtures of water and other liquids, gases or other substances into the distribution pipes of the potable supply of water from any source or sources.

When water enters your home or business from the main water supply line, it should only ever flow in one direction: into your home or business.

But sometimes, due to pressure changes in the pipes, that water will flow backwards and seep back into the main water supply line.


When Backflow  happens when there’s a break in the main water line or when a fire hydrant is opened for use. Because pressure is lost during these events, water is no longer being pushed forward into your home and flows backwards into the city water lines.

And when this happens, backflow can contaminate the public drinking supply with:

• Fertilizers and pesticides from irrigation sprinklers
• Stagnant and possibly toxic water, including antifreeze liquids, in your fire sprinkler pipes
• Toxic chemicals from mechanical or food process lines
Food and detergent waste from commercial soap dispensers and dishwashers

Backflow prevention systems are devices installed onto a pipe that only allow water to flow in one direction.

Think of it as a one-way gate that allows water from the city’s public water supply to flow into your home’s piping but stops water if it ever tries to flow backwards into the main water supply.

State Law requires backflow preventers to be tested annually by an EPA certified plumber as well as NFPA 13.7.1.

Mechanical backflow preventers have internal seals, springs, and moving parts that are subject to fouling, wear, or fatigue. Also, mechanical backflow preventers and air gaps can be bypassed. Therefore, all backflow preventers must be tested annually to ensure that they are functioning properly. A visual check of air gaps is acceptable, but mechanical backflow preventers must be tested with properly calibrated gauge equipment.

Causes of backflow failures:

Failure in backflow preventers is due to the dirt and debris that flows through the pipeline. The check valve will foul when the debris gets caught between the disc and seat.Each backflow assembly has internal components that will experience normal wear and will require service from time to time.

The check valve is a major component within any backflow assembly. The check valve consists of a poppet, spring, guide, seat and seating surface (rubber disc). The rubber sealing surface and guide mechanisms get the most wear and typically will require regular cleaning or replacement. If the seat of the check valve is damaged in any way, it will need to be replaced. Check valve springs normally only need to be replaced if they are broken or damaged.

Valley Fire Protection and Plumbing is staffed with well-trained and extremely knowledgeable Cross Connection Control Device Certified Plumbers. We offer competitive pricing for backflow testing as well as any repairs.

Request a quote today! We are available 24 hours a day, 7 days a week, should any emergency arise. We are also a full-service plumbing shop staffed with reliable and professional plumbers to service any plumbing issues in your home or business. Please feel free to call or email us for information.

Related Topics: Backflow
By: Tom Hartel
I acquired my expertise by directing day-to-day operations of the business for over 20 years. Continuous hard work helped me become a nationally recognized speaker and expert on fire protection, fire sprinklers, special hazards, and plumbing systems. In this blog, I share my knowledge that will hopefully help you make better decisions for your projects.


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