Prepare Dishwasher Connection (Optional) — Knock Out Garbage Disposal Plug
Part of project
How to Install a Dishwasher Air Gap on a Countertop · Step 5 of 7
In this video
If you are connecting a dishwasher drain hose to the disposal, you must remove the knockout plug. Place the disposal on its side. Insert the tip of a screwdriver into the dishwasher drain inlet and gently tap it with a hammer to break the plug loose. Turn the disposal over and use a pair of pliers to reach inside and remove the loosened plastic plug. If you are not connecting a dishwasher, skip this step and leave the plug in place.
Goal: Remove dishwasher knockout plug
- Do not remove the drain plug if a dishwasher drain hose will not be connected to the disposer.
Used in this video
- Screwdriver (Tool Type: Screwdriver) — Breaking the dishwasher knockout plug.
- Hammer (Tool Type: N/A) — Tapping the screwdriver to break the knockout plug.
- Pliers (Tool Type: Pliers, Pliers_Type: Needle_nose_pliers) — Removing the loosened knockout plug from inside the disposal.
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FAQs
Is a dishwasher air gap really necessary, or can I skip it to avoid drilling a hole in my countertop?
An air gap is a crucial plumbing safety device designed to prevent contaminated water from siphoning back into your clean dishwasher, especially if the drain clogs. While some local codes allow for a "high loop" drain hose as an alternative, many jurisdictions, like California, still require a physical air gap. Always check your local plumbing codes to ensure compliance and maintain proper sanitation.
Drilling a hole in my countertop sounds intimidating. What type of drill and hole saw do I need, and how can I ensure a clean cut?
For a clean hole, you'll need a powerful drill like the Makita 7 Amp 1/2 in. 900 RPM Drill and a bi-metal hole saw from a kit like the Milwaukee Hole Dozer set, sized correctly for your air gap (typically 1-1/4 to 1-1/2 inches). Start with a pilot hole, use steady pressure, and drill slowly, especially for harder materials like granite or quartz, to prevent chipping. Placing painter's tape on the countertop can also help prevent surface damage.
What are the most common mistakes people make when installing an air gap, especially concerning leaks?
The most common mistakes involve improperly connecting the hoses and not securing them tightly. Ensure all hose connections are seated firmly and secured with stainless steel hose clamps, like the Everbilt 5/16 - 5/8 in. Stainless Steel Hose Clamp. Additionally, apply a small ring of plumber's putty, like Oatey 14 oz. Plumber's Putty, under the air gap's top flange before tightening it down to create a watertight seal against the countertop.
My kitchen design doesn't really allow for an air gap on the countertop. Are there any alternative methods to prevent dishwasher backflow?
Yes, in some areas, a "high loop" installation is an acceptable alternative to a countertop air gap. This involves securing the dishwasher drain hose in a high arch under the sink, ensuring it rises above the flood level of the sink or disposal connection. However, local plumbing codes vary, so it's essential to verify if this method is permitted in your area before skipping the air gap.
Prepare Dishwasher Connection (Optional) — Knock Out Garbage Disposal Plug
Part of project
How to Install a Dishwasher Air Gap on a Countertop · Step 5 of 7
In this video
If you are connecting a dishwasher drain hose to the disposal, you must remove the knockout plug. Place the disposal on its side. Insert the tip of a screwdriver into the dishwasher drain inlet and gently tap it with a hammer to break the plug loose. Turn the disposal over and use a pair of pliers to reach inside and remove the loosened plastic plug. If you are not connecting a dishwasher, skip this step and leave the plug in place.
Goal: Remove dishwasher knockout plug
- Do not remove the drain plug if a dishwasher drain hose will not be connected to the disposer.
Used in this video
- Screwdriver (Tool Type: Screwdriver) — Breaking the dishwasher knockout plug.
- Hammer (Tool Type: N/A) — Tapping the screwdriver to break the knockout plug.
- Pliers (Tool Type: Pliers, Pliers_Type: Needle_nose_pliers) — Removing the loosened knockout plug from inside the disposal.
Frequently Asked Questions
Is a dishwasher air gap really necessary, or can I skip it to avoid drilling a hole in my countertop?
An air gap is a crucial plumbing safety device designed to prevent contaminated water from siphoning back into your clean dishwasher, especially if the drain clogs. While some local codes allow for a "high loop" drain hose as an alternative, many jurisdictions, like California, still require a physical air gap. Always check your local plumbing codes to ensure compliance and maintain proper sanitation.
Drilling a hole in my countertop sounds intimidating. What type of drill and hole saw do I need, and how can I ensure a clean cut?
For a clean hole, you'll need a powerful drill like the Makita 7 Amp 1/2 in. 900 RPM Drill and a bi-metal hole saw from a kit like the Milwaukee Hole Dozer set, sized correctly for your air gap (typically 1-1/4 to 1-1/2 inches). Start with a pilot hole, use steady pressure, and drill slowly, especially for harder materials like granite or quartz, to prevent chipping. Placing painter's tape on the countertop can also help prevent surface damage.
What are the most common mistakes people make when installing an air gap, especially concerning leaks?
The most common mistakes involve improperly connecting the hoses and not securing them tightly. Ensure all hose connections are seated firmly and secured with stainless steel hose clamps, like the Everbilt 5/16 - 5/8 in. Stainless Steel Hose Clamp. Additionally, apply a small ring of plumber's putty, like Oatey 14 oz. Plumber's Putty, under the air gap's top flange before tightening it down to create a watertight seal against the countertop.
My kitchen design doesn't really allow for an air gap on the countertop. Are there any alternative methods to prevent dishwasher backflow?
Yes, in some areas, a "high loop" installation is an acceptable alternative to a countertop air gap. This involves securing the dishwasher drain hose in a high arch under the sink, ensuring it rises above the flood level of the sink or disposal connection. However, local plumbing codes vary, so it's essential to verify if this method is permitted in your area before skipping the air gap.