Dishwasher Backflow Preventer: What You MUST Know NOW!

Understanding Your Dishwasher Backflow Preventer

This guide explains everything you need to know about dishwasher backflow preventers, ensuring your home’s water supply remains safe and clean.

What is a Dishwasher Backflow Preventer?

A dishwasher backflow preventer (also sometimes called an air gap) is a safety device designed to stop contaminated water from your dishwasher flowing back into your home’s clean water supply. Imagine dirty dishwater potentially mixing with the water you drink or use for cooking – this device prevents that. It’s essentially a one-way valve or a physical separation to prevent backflow.

Why is a Dishwasher Backflow Preventer Important?

Backflow can happen when the water pressure in your dishwasher is higher than the water pressure in your supply lines. This can occur due to various factors, such as a sudden drop in city water pressure, or increased pressure due to well systems.

• Protecting Your Drinking Water: The primary reason is to keep your drinking water safe and free from contamination.
• Preventing Illness: Dishwater contains food particles, detergents, and bacteria. Consuming contaminated water can lead to illness.
• Meeting Plumbing Codes: Many local plumbing codes require a dishwasher backflow preventer for safety. Not having one could result in fines or issues during home inspections.

Types of Dishwasher Backflow Preventers

There are two main types of backflow preventers commonly used with dishwashers:

1. Air Gap: This is the most common and generally considered the most effective type. It creates a physical separation between the dishwasher drain hose and the drainpipe, preventing any possibility of backflow. It’s usually a small, chrome-plated device mounted on the sink deck near the faucet.

   • How it Works: The dishwasher drain hose connects to the air gap, and the air gap drain is then routed to the drainpipe. The air gap allows wastewater to flow downward into the drain, but prevents it from flowing backward.

2. High Loop: This is a less effective, but often used alternative. It involves looping the dishwasher drain hose as high as possible under the sink before connecting it to the drain.

   • How it Works: By elevating the drain hose, gravity helps prevent backflow. However, this method isn’t as reliable as an air gap, as it doesn’t provide a complete physical separation.

Identifying Your Dishwasher Backflow Preventer

Locating an Air Gap:

Look for a small, cylindrical, chrome-finished device mounted on your sink deck, usually near the faucet. It has small holes or slots in the side. If you find this, you have an air gap installed.

Checking for a High Loop:

Open the cabinet under your sink and look at the dishwasher drain hose. Is it routed as high as possible, secured with a clamp, before connecting to the drain line or garbage disposal? If so, you likely have a high loop.

Maintaining Your Dishwasher Backflow Preventer

Proper maintenance ensures your backflow preventer functions correctly.

Cleaning an Air Gap:

Air gaps can sometimes become clogged with debris, leading to drainage issues.

1. Disconnect Power: Turn off the dishwasher and disconnect its power supply.
2. Remove Cover: Carefully remove the chrome cover of the air gap.
3. Clean Debris: Use a small brush or pipe cleaner to remove any food particles or buildup from the air gap body and the connecting hoses.
4. Flush with Water: Flush the air gap with water to ensure clear passage.
5. Reassemble: Reattach the cover and reconnect the dishwasher’s power supply.

Inspecting a High Loop:

Regularly check the high loop to ensure it remains properly secured and elevated. If the hose has sagged or become disconnected, re-secure it to maintain its effectiveness.

Troubleshooting Common Issues

Issue	Possible Cause	Solution
Dishwasher not draining	Clogged air gap or drain hose	Clean the air gap and check for blockages in the drain hose.
Water backing up into sink	Clogged drain line or faulty check valve (in some models)	Check and clear the drain line. If a check valve exists, consider replacement.
Unusual noises	Air gap malfunctioning	Inspect and clean the air gap. If problems persist, consider replacing it.

Replacing a Dishwasher Backflow Preventer (Air Gap)

If your air gap is damaged or severely clogged, replacing it is a straightforward DIY project.

1. Turn Off Water and Power: Shut off the water supply to the dishwasher and disconnect its power.
2. Disconnect Hoses: Carefully disconnect the hoses connected to the old air gap.
3. Remove Old Air Gap: Unscrew and remove the old air gap from the sink deck.
4. Install New Air Gap: Insert the new air gap into the hole and secure it tightly.
5. Reconnect Hoses: Reconnect the hoses to the new air gap, ensuring they are properly secured.
6. Restore Water and Power: Turn the water supply back on and reconnect the dishwasher’s power.
7. Test: Run the dishwasher to ensure the new air gap is functioning correctly.

Note: If you’re uncomfortable with plumbing or electrical work, it’s always best to consult a qualified plumber.

Hopefully, you now have a much better understanding of the dishwasher backflow preventer! If you’re still unsure, reach out to a local plumber to get their take on your specific situation. Stay safe, and happy dishwashing!