Check Valve Installation Techniques for Backflow Prevention

How you place your check valve is more important than you might think for keeping your plumbing safe from backflow and the resulting damage that can be costly. Whether you own a home or a busy business, understanding the correct check valve installation techniques is crucial to ensure water flows in the right direction and prevent future problems.

We know what happens when check valves aren't put in correctly here at All Needs Plumbing. A handyman (not from our team) installed a check valve incorrectly for one client, I recall. It caused the water flow to drop and even led to a small flood in their garage. It was easy for us to fix, but it was an expensive mistake that could have been avoided by having a professional do the work.

Why Proper Check Valve Installation Is Essential

Check valves only let water flow in one direction. They prevent any backflow that could damage equipment or contaminate the system. However, if you install the valve incorrectly—such as in the wrong direction or too close to bends and fittings—it won’t function properly. This can lead to leaks, water hammer (a sudden pressure surge), or even system failure. Proper installation ensures your plumbing system stays safe, efficient, and long-lasting.

Key Steps in Check Valve Installation

1. Choose the Right Valve for Your System

Selecting the correct type and size of check valve is the first step to a successful installation. We assess your pipe size, water pressure, and the environment to recommend the best valve type. For example, swing check valves work well in horizontal pipes because they rely on gravity to close. In contrast, spring-assisted valves are better suited for vertical runs, as they utilise a spring mechanism to close independently of gravity. Choosing the wrong valve can cause malfunction or damage, so this step is critical. Additionally, consider the media type—whether it’s clean water, wastewater, or chemical fluids—as some valves are better suited to handle solids or corrosive materials than others.

2. Position the Valve Correctly

Where you place the valve in your piping system affects its performance. Always install the valve with the flow arrow pointing in the direction of water flow. This simple step ensures the valve opens and closes as intended. Also, make sure there’s enough straight pipe—at least 5 to 10 pipe diameters—before and after the valve.

This spacing reduces turbulence and noise, prevents premature wear, and helps the valve operate smoothly. For example, avoid installing a check valve immediately after an elbow or a tee, as these fittings create turbulence that can cause valve chatter, instability, and eventual failure.

3. Install with Care

Before installation, our plumbers shut off the water supply and drained the pipes to avoid spills and water damage. We clean the pipe ends and inspect the valve for any debris or damage that could affect performance. For swing check valves, we manually check that the disc or flapper moves freely without obstruction. 

Then, we securely fit the valve using the appropriate connection type—whether threaded, socket, or flange—making sure it’s adequately aligned without overtightening, which can cause leaks or damage. Taking the time to do this right prevents future leaks and system issues.

4. Test the System

Once installed, we restore water flow and check for leaks and proper valve operation. This step confirms your system is safe and efficient. We listen for unusual noises, check pressure levels, and ensure the valve closes fully to prevent backflow. Testing gives you peace of mind that your plumbing is protected.

Installation Orientation: Vertical or Horizontal?

Most check valves, especially swing types, should be installed horizontally to ensure proper operation. Installing them vertically can cause the valve to malfunction or leak because gravity affects the valve’s movement. For vertical pipe runs, spring-loaded or axial-flow check valves are preferred because they utilise a spring mechanism to close independently of gravity. 

This design prevents water hammer by ensuring the valve closes quickly and smoothly. In fact, in demanding applications such as mining or tall buildings, these valves help prevent pump head loss and dangerous backflow that can cause severe damage or pose safety risks.

Pro-Tip: Never install a check valve too close to elbows, tees, or pumps. Allow at least 5 to 10 pipe diameters of straight pipe before the valve to minimise turbulence and noise. This simple spacing dramatically improves valve longevity and reduces system noise.

Maintenance and Troubleshooting

Regular inspections help catch issues early. Inspect the valve for leaks, rust, or debris. If you hear banging noises, it might be water hammer caused by a valve closing too abruptly. In such cases, upgrading to a spring-assisted valve or adding a water hammer arrestor can help. Keeping your valves clean and checking their operation every few months helps extend their life and ensures your water flows smoothly.

Pro-Tip: When installing on a vertical pipe, opt for a spring-assisted check valve rather than a swing valve to ensure proper closing and avoid water hammer, which can cause damage and loud banging noises.

FAQs About Check Valve Installation Techniques

What is the primary concern when installing a check valve?

The primary concern is ensuring the valve is installed in the correct flow direction. The valve must be aligned with the flow arrow on the body to function correctly and prevent backflow.

Should check valves be put in horizontally or vertically?

Swing check valves are best installed horizontally. Spring-assisted check valves can be installed vertically and are preferred for vertical pipe runs to avoid water hammer.

Does it matter where a check valve goes?

Yes. Check valves should be installed at least five to ten pipe diameters away from elbows, tees, and other fittings to reduce turbulence and wear.

What is the water hammer after installing a check valve?

Water hammer is a pressure surge caused when a valve closes suddenly, creating a shock wave in the pipes. It can cause noise, vibration, and damage if not properly managed.

Can you install a check valve on its side?

It depends on the valve type. Swing check valves generally should not be installed on their side, while spring-loaded valves can be installed in various orientations.

What if I want to know more about check valve installation techniques?

All Needs Plumbing is here for you if you would like to know more or need assistance with check valve installation techniques. Our team has a $0 callout fee when we visit your home or business. We also offer same-day service 24 hours a day, 7 days a week, because plumbing problems don't wait for work hours. 

We also help you save money by giving 15% off for seniors and $150 off hot water systems. Let us install your check valve with the care and skill it needs, whether you're a homeowner or the owner of a business. Contact us immediately to ensure the job is done correctly the first time.

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