Dishwasher Air Gap vs High Loop: Which is Better for Plumbing?

One of the most critical yet often overlooked components of a dishwasher installation is the method used to prevent backflow—water from the kitchen sink or drain flowing back into the dishwasher.

Backflow not only leads to unsanitary conditions but can also damage your appliance. When it comes to protecting your dishwasher from this issue, there are two main options: the dishwasher air gap vs high loop method.

Understanding the difference between these two options is essential for homeowners installing a dishwasher or maintaining their dishwashers.

Both the air gap and high loop are designed to prevent wastewater from contaminating the dishwasher, but they differ in effectiveness, installation, and plumbing code requirements.

In this guide, we’ll explore the dishwasher air gap vs. high loop debate, outlining the pros, cons, and key differences between the two methods.

This will help you decide which option is best for your plumbing setup, including some air gap alternatives to consider.

What Is a Dishwasher Air Gap?

A dishwasher air gap is a small vertical pipe installed near the kitchen sink faucet. It includes an air gap fitting and typically requires drilling a hole in the counter to install.

The air gap works by allowing air into the system, breaking the siphon effect that could potentially draw dirty water back into the dishwasher. This prevents contamination of your clean dishes.

Many homeowners like the air gap because it’s a visible safety feature, but others find the additional hole in the counter unsightly.

If you don’t want to drill a hole, you can consider some dishwasher air gap alternative, such as using a high loop or installing check valves.

Key Features of a Dishwasher Air Gap:

• Backflow Prevention: The air gap is the most effective method for preventing backflow, as it physically separates the dishwasher from the drain.
• Installation Location: Typically, an air gap is installed on the sink or countertop, near the faucet.
• Plumbing Code Requirements: In some regions, local plumbing codes mandate the use of an air gap for dishwashers, making it a legal requirement.

While highly effective, air gaps may be considered less aesthetically pleasing since they require a visible fixture on the countertop.

Despite this, many homeowners choose the air gap for its proven ability to prevent backflow and water contamination.

What Is a Dishwasher High Loop?

A high loop is another method of backflow prevention, but it doesn’t require an air gap or drilling a hole in the counter.

Instead, the dishwasher drain hose is looped as high as possible under the kitchen sink before connecting to the drain system. The idea is that gravity helps prevent dirty water from flowing backward into the dishwasher.

While the high loop is less obtrusive and easier to install, it may not be as effective as the air gap in all situations. For instance, it doesn’t offer the same degree of physical separation, which can be important in areas with stricter plumbing codes.

Key Features of a Dishwasher High Loop:

• Backflow Prevention: While the high loop can effectively prevent backflow in many cases, it’s not as foolproof as an air gap. In instances of severe blockages, backflow can still occur.
• Installation Process: The high loop method is simple to install and requires no additional hardware. It’s often chosen for DIY installations because it doesn’t require drilling into the countertop.
• Plumbing Code: In some regions, a high loop is not considered sufficient protection, and local codes may require an air gap instead.

The high loop is a more discreet solution since it’s installed under the sink and out of sight. It’s also easier and less expensive to install, making it a popular option for homeowners who don’t face strict plumbing code requirements.

Key Differences Between Air Gap and High Loop

When comparing the air gap vs. high loop methods, several important factors come into play, including effectiveness, installation complexity, and adherence to local plumbing codes.

Plumbing Code Requirements

In many areas, building and plumbing codes require an air gap for dishwasher installations, especially in new construction. This is due to the air gap’s superior ability to prevent backflow.

On the other hand, the high loop may be sufficient in regions with less stringent regulations, but it’s important to check local codes before deciding.

Backflow Prevention Efficiency

The air gap is generally considered the most reliable method for preventing backflow. By creating a physical barrier between the dishwasher and drain, it eliminates the possibility of dirty water entering the dishwasher.

While the high loop can also prevent backflow, it’s less effective in cases of extreme pressure or blockages.

Installation Complexity

Installing an air gap requires drilling a hole in the countertop or sink, which can be more labor-intensive and may require professional help. A high loop, by contrast, is much simpler to install and can be done by most homeowners without special tools.

Aesthetic and Space Considerations

Air gaps take up space on the countertop and may not align with the aesthetic preferences of some homeowners. The high loop, on the other hand, is hidden under the sink, making it a more visually discreet option.

Pros and Cons of Dishwasher Air Gap

The dishwasher air gap offers many benefits, but it also has some drawbacks. Here’s a closer look at the pros and cons of using an air gap.

Pros

• Best Backflow Prevention: The air gap is the most effective method for preventing backflow into the dishwasher.
• Plumbing Code Compliance: Required by plumbing codes in many areas, ensuring your installation meets legal standards.
• Easy to Inspect: Any backflow issue becomes immediately visible, as water will overflow from the air gap rather than re-enter the dishwasher.

Cons

• Countertop Aesthetics: The air gap is installed on the sink or countertop, which some homeowners may find unattractive.
• Space Requirements: The air gap takes up valuable space on the counter, which may be an issue in smaller kitchens.
• Complex Installation: Installing an air gap requires drilling into the countertop or sink, which can complicate the installation process.

Pros and Cons of Dishwasher High Loop

While the high loop is simpler and less invasive, it also has limitations compared to the air gap. Here are the key pros and cons of using a high loop.

Pros

• Easy Installation: The high loop is straightforward to install, making it a great DIY option for homeowners.
• Cost-Effective: Since it requires no additional hardware, the high loop is a more affordable solution.
• Discreet Design: Installed under the sink, the high loop is hidden from view, preserving the aesthetics of the kitchen.

Cons

• Less Effective in Backflow Prevention: While effective in many cases, the high loop may not provide the same level of protection as an air gap, particularly in areas with strong water pressure.
• Not Code-Compliant Everywhere: Some local plumbing codes don’t recognize the high loop as sufficient protection, requiring the use of an air gap instead.
• Potential for Failure: If the drain hose becomes loose or damaged, the high loop’s effectiveness is compromised.

Which Is Better for Your Plumbing: Dishwasher Air Gap vs High Loop?

The choice between a dishwasher air gap and a high loop depends on several factors, including local plumbing codes, personal preferences, and how concerned you are about backflow prevention.

• If your local plumbing code requires an air gap, then that is your best option. Air gaps provide the highest level of protection against backflow, making them the safest choice for areas where contamination is a concern.
• If you’re looking for a simpler, more affordable solution, and local codes allow it, the high loop can be a good choice. It’s easy to install, doesn’t require drilling into the countertop, and offers adequate backflow prevention for most households.

Ultimately, the decision between a dishwasher air gap and a high loop comes down to your personal preference and local plumbing regulations. If your area requires an air gap by code, then that’s the route you’ll have to take.

However, if you’re looking for something less obtrusive or don’t want to drill a hole in the counter, a high loop or one of the air gap alternatives may be more suitable.

Remember, both systems are designed to protect your dishwasher from dirty water, so whichever method you choose, be sure it’s installed properly for maximum efficiency and safety.

Air Gap and High Loop Alternatives

For those who prefer not to use an air gap, there are air gap alternatives like installing check valves in the dishwasher drain line. Check valves allow water to flow in only one direction, helping to prevent backflow into the dishwasher without needing a physical air gap fitting.

In addition to check valves, some modern dishwashers come equipped with built-in backflow prevention systems, eliminating the need for an external air gap or high loop altogether. Always consult your local plumbing code to ensure you’re using the best solution for your home.

FAQs

Conclusion

When deciding between a dishwasher air gap vs. high loop, it’s important to weigh the pros and cons of each method based on your specific needs.

The air gap is the best choice for those who want maximum backflow protection and compliance with local plumbing codes, while the high loop offers a more affordable, DIY-friendly option.

Both the dishwasher air gap and high loop are effective methods for preventing backflow, but they serve different purposes depending on your plumbing needs and local codes.

If you’re in an area where air gaps are required, or if you want the highest level of protection, an air gap is the best choice.

However, if you prioritize a simpler installation and cleaner aesthetic, a high loop may be the more appealing option.

Check your local plumbing codes and consider your aesthetic preferences and installation needs when choosing the best method for your dishwasher.

No matter which method you choose, ensuring that your dishwasher is properly connected to your home’s plumbing system is essential for maintaining a safe and efficient kitchen.