Washing Machine Check Valves: Everything You Need to Know

A washing machine check valve is a crucial component that serves as a backflow preventer in your washing machine. This non-return valve or one-way valve ensures that water only flows in one direction, preventing backflow into the device.

Its functionality is vital for your washing process’s safety, hygiene, and sanitation, as it stops wastewater from re-entering the machine or your home’s plumbing fixtures.

Understanding and installing a check valve is key to water damage prevention and the longevity of your washing machine.

In this blog post, we will deep dive into what check valves are, their installation, pros and cons, and more…

What is a Washing Machine Check Valve?

A check valve, also known as a non-return valve or one-way valve, is a mechanical component designed to allow fluid to flow in only one direction.

In the context of a washing machine, this valve is often referred to as a washing machine check valve.

The primary functionality of this valve is to act as a backflow preventer.

It ensures that once the water has been pumped out of the machine by the drain pump, it doesn’t flow back into the machine’s tub.

This is crucial for maintaining the hygiene and sanitation of your laundry and the machine itself.

By preventing backflow, the check valve also protects the drainage system and other plumbing fixtures from potential water damage.

How Does a Washing Check Valve Work?

The mechanism of a washing check valve is ingeniously simple yet highly effective.

At its core, the valve contains a spring-loaded valve, ball bearing, or a flap known as a flapper-style check valve.

When the water flow is initiated by the drain pump, the pressure pushes this internal component open, allowing water to flow out through the drain hose.

However, when the drain pump stops, the pressure drops and the internal component returns to its original position, effectively sealing off the valve.

This action prevents any backflow of water into the washing machine or water supply line, ensuring hygiene and safety.

The check valve is designed to open and close automatically, regulating the flow of liquid based on the pressure in the system.

This functionality is what makes it an effective backflow preventer and an essential part of your washing machine’s drainage system.

Types of Check Valves

When it comes to washing machine check valves, there are several types to consider, each with its unique features and benefits.

Understanding these types of check valves can help you make an informed decision for your appliance. Here are the main types:

Swing-style Check Valve

The Swing-style check valve uses a swinging arm to regulate water flow.

When water flows through, the arm swings out of the way, and when the flow stops, it swings back into place, blocking the flow.

Ball Check Valves

In a Ball-style check valve, a ball seated in a cage blocks the flow of water.

The ball lifts off its seat when water flows through, and falls back into place when the flow stops.

Flapper Check Valve

The Flapper-style check valve is the most common type found in washing machines.

It consists of a rubber flapper attached to a spring-loaded arm.

When water flows through the valve, the flapper opens, allowing water to pass.

Once the flow stops, the flapper closes, preventing backflow into the drain pump.

Diaphragm Check Valve

The Diaphragm-style check valve uses a flexible diaphragm to block the flow of water.

The diaphragm moves out of the way when water flows through and returns to its original position when the flow stops.

It’s worth noting that the Flapper-style check valve is the most widely used type due to its simplicity and effectiveness.

Stop Check Valve

Stop check valves have a valve stem that allows manual control in addition to automatic check valve functionality.

This can be useful for maintenance or troubleshooting.

Washer-Specific Check Valves

Some washing machines may use specialized check valves designed specifically for their models, ensuring compatibility and optimal performance.

Importance of Check Valves

The importance of check valves in washing machines cannot be overstated.

These small but vital components play a significant role in ensuring the longevity and functionality of your appliance. Here’s why:

Preventing Water Damage

Check valves act as backflow preventers, stopping wastewater from flowing back into the machine or your home’s plumbing system.

This prevention is crucial for avoiding water damage, not just to your washing machine but also to your home’s infrastructure.

Maintaining Hygiene and Sanitation

A check valve ensures that dirty water doesn’t re-enter the washing machine, maintaining the hygiene and sanitation of your laundry.

This is particularly important in households with young children or individuals with compromised immune systems.

Protecting the Drain Pump and Water Supply Line

The check valve protects the drain pump and water supply line from potential damage.

If wastewater were to flow back into the machine, it could lead to pump failure or even contaminate the water supply, leading to more severe issues.

Compliance with Local Building Codes

In some areas, local building codes may require the installation of a check valve in the water supply line to a washing machine.

Failure to comply could result in fines or legal repercussions.

Scenarios Where a Check Valve is Crucial

High-Rise Living: In multi-story buildings, the risk of water siphoning back into the machine is higher due to gravitational pull, making a check valve essential.

Unstable Water Pressure: In areas where water pressure is inconsistent, a check valve can prevent backflow when the pressure suddenly drops.

Shared Plumbing Systems: In buildings with shared plumbing, a check valve can prevent cross-contamination between different units.

Installation Guide (How to install washing machine check valves?)

Installing a washing machine check valve is a crucial step to ensure the longevity and functionality of your washing machine.

This guide will walk you through the installation process, combining insights from both sources for a thorough understanding.

Tools and Supplies You’ll Need:

  • Pipe wrench
  • Adjustable pliers
  • Pipe cutter
  • Teflon tape
  • Silicone sealant
  • The check valve itself

Step 1: Locate the Water Supply Line

Identify the water supply line that connects to your washing machine.

This is usually a flexible hose that links the machine to a water supply valve or a pipe in the wall.

Step 2: Turn Off the Water Supply

For safety reasons, make sure to turn off the water supply to the washing machine before proceeding.

Step 3: Cut the Water Supply Line

Using a pipe cutter, carefully cut the water supply line at a convenient point for installing the check valve.

Ensure you leave enough slack for the movement of the washing machine.

Step 4: Install the Check Valve

Depending on the type of check valve you have, the installation process may vary.

Generally, one end of the valve attaches to the water supply line and the other to the washing machine. Use Teflon tape for a secure seal if required.

Step 5: Test the Check Valve

Turn the water supply back on and test the valve to ensure it’s functioning correctly.

If you notice any leaks or other issues, turn off the water supply and make adjustments.

Step 6: Secure the Check Valve

Once you confirm the check valve is working as expected, use a pipe wrench and adjustable pliers to secure it in place followed by tightening all connections to prevent leaks.

By following these steps, you can ensure that your washing machine check valve is installed correctly, offering backflow prevention and water damage prevention for your appliance.

Maintenance and Troubleshooting

Maintaining your washing machine check valve is essential for its long-term functionality and efficiency.

A well-maintained check valve ensures backflow prevention, thereby safeguarding your washing machine and other plumbing fixtures from potential water damage.

Long-term Maintenance Requirements

  • Regular Inspection: Periodically inspect the check valve for signs of wear and tear. Look for any cracks, rust, or other visible damage that could impair its function.
  • Cleaning: Over time, check valves can accumulate debris, affecting their performance. Use a small brush or pipe cleaner to gently scrub away any dirt or debris from the valve.
  • Seal Check: Ensure that the seals around the check valve are intact. Replace any worn-out seals to prevent leaks.
  • Pressure Testing: Occasionally, test the water pressure on both sides of the check valve to ensure it is operating within the recommended range.
  • Replacement: Depending on the material, whether stainless steel, brass, or plastic, and the quality of your water supply, you may need to replace the check valve every few years.
  • Local Building Codes: Always check your local building codes for any specific maintenance requirements or guidelines related to check valves.

Symptoms of a Faulty Check Valve and How to Address Them

A faulty check valve can lead to several issues that may compromise the functionality and safety of your washing machine.

Here are some common symptoms and how to address them:

Water Backflow

If you notice water flowing back into the washing machine or the drain hose, it’s a clear sign that the check valve is not functioning correctly.

Solution: Inspect the valve for any blockages or damage and clean or replace it as needed.


If there’s water leaking around the valve, the seals might be worn out or damaged.

Solution: Replace the seals or the entire valve if necessary.

Unusual Noises

Hearing strange sounds like whistling or humming from the valve can indicate a malfunction.

Solution: This usually requires troubleshooting by disassembling the valve and checking for any obstructions or damage.

Reduced Water Pressure

If you notice a significant drop in water pressure, the valve might be partially blocked.

Solution: Clean the valve thoroughly to remove any debris or consider replacing it if the issue persists.

Alternatives to Check Valves

While check valves are highly effective for backflow prevention, there are alternative mechanisms like air gaps and standpipes that can also serve the same purpose.

Air Gaps

An air gap is a physical separation between the water outlet and the flood level of a fixture. While effective, they can be bulky and less aesthetically pleasing.


These are vertical pipes connected to a P-trap, providing a physical barrier to backflow. They are simpler but may require more space.

Effectiveness Comparison

  • Check Valves: Highly effective and compact but may require periodic maintenance.
  • Air Gaps: Very effective but can be bulky and less visually appealing.
  • Standpipes: Effective and simple but may take up more space.

Each of these options has its pros and cons, and the best choice may depend on your specific needs, local building codes, and the layout of your plumbing fixtures.

Final Thoughts

Understanding and installing a washing machine check valve is not just a matter of compliance with local building codes; it’s about ensuring the longevity, safety, and hygiene of your washing machine and home.

From backflow prevention to water damage prevention, the benefits are manifold.

Whether you opt for a check valve or its alternatives like air gaps and standpipes, the key is to choose a system that best suits your needs and to maintain it effectively.

Frequently Asked Questions

How often should I inspect my washing machine check valve?

It’s advisable to inspect your check valve at least once a year for any signs of wear and tear or blockages.

Can I install a check valve myself?

Yes, installing a washing machine check valve is a straightforward process, but if you’re not comfortable with DIY tasks, it’s best to hire a professional.

What materials are check valves typically made of?

Check valves are commonly made from stainless steel, brass, or plastic, each with its own pros and cons.

Is a check valve necessary for all washing machines?

While it’s highly recommended, the necessity may depend on your local building codes and specific plumbing fixtures.

What are the alternatives to a check valve?

Alternatives include air gaps and standpipes, which also offer effective backflow prevention but may have different space and aesthetic considerations.

Hemant Sarkar is a seasoned techie with a diploma in computer science and an impressive track record of over 15 years in dealing with speakers, kitchen appliances, and various home appliance-related issues. He is widely recognized for his exceptional expertise in repairing dryers and washing machines from all major brands. In addition to his appliance repair prowess, Hemant maintains engaging blogs on topics related to music and speakers. For any inquiries or assistance regarding appliances or tech-related matters, you can reach out to him at: hemant (at) theportablelaundry.com.