Should I have an air gap for my dishwasher?

Yes, an air gap is an important backflow prevention device that protects your drinking water supply from contaminated dishwasher drain water.

What an Air Gap Does

An air gap creates a physical separation between your dishwasher drain line and the household drain system. Without it, there's a risk of backflow — contaminated water from your sink drain siphoning back into your dishwasher, and potentially into your water supply. It's a simple but critical protection for your family's health.

How It Works

The air gap is typically a small chrome or stainless fitting mounted on your kitchen countertop or sink deck. Your dishwasher drain hose connects to one side, and a second hose runs from the air gap down to your sink drain or garbage disposal. The "gap" of open air in the middle physically prevents any backflow from occurring — no water can travel upward through open air.

Ottawa-Specific Context

Ontario Building Code and local requirements around dishwasher drain connections can vary depending on your installation. Some installations use a high loop method as an alternative — where the drain hose is looped up high under the counter before connecting to the drain. Whether an air gap is specifically required in your Ottawa home is something to confirm with a licensed plumber or Ottawa Building Services, as requirements can depend on your specific setup and when your home was built.

The Bottom Line

Even if not strictly required in your situation, an air gap is considered best practice by most plumbers because it provides reliable, passive backflow protection with no moving parts to fail. A high loop is a common alternative but is generally considered less reliable since it depends on maintaining proper hose positioning over time.

If you're installing a new dishwasher or renovating your kitchen, it's a great time to have a licensed plumber confirm the right drain configuration for your home. Ottawa Pro Plumbing can assess your setup and ensure your dishwasher drain meets current standards — feel free to reach out for a free consultation.