First-Time Garbage Disposal Installation
Updated February 20, 2026
Adding a disposal to a sink that never had one is a bigger job than a simple replacement, but still very doable. The extra steps: installing the mounting assembly and sink flange, connecting to the existing drain, and getting power to the unit. The plumbing side is straightforward. The electrical side -- running a new circuit or adding a switch -- is where most people decide to call in help.
Overview
Adding a disposal to a sink that never had one is a bigger job than a simple replacement, but still very doable. The extra steps: installing the mounting assembly and sink flange, connecting to the existing drain, and getting power to the unit. The plumbing side is straightforward. The electrical side -- running a new circuit or adding a switch -- is where most people decide to call in help.
What to Know
Tools & Materials
- Plumber's putty
- Screwdriver (flathead and Phillips)
- Adjustable wrench and pliers
- Hacksaw (for cutting drain pipe)
- Wire strippers and wire nuts
- Disposal mounting assembly and unit
Step by Step
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Plan the electrical connection
Decide on switched outlet or hardwired setup. Check your breaker panel for an available circuit. No spare circuit? This step is for an electrician.
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Install sink flange and mounting assembly
Remove existing sink strainer. Clean the opening. Roll plumber's putty around new flange, press into opening from above. From below, assemble mounting ring, snap ring, and backup flange. Tighten evenly until putty squeezes out.
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Wire the disposal
With breaker off, connect wires to the disposal junction box: black to black, white to white, green to ground screw. Secure cable with strain relief clamp.
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Mount and connect plumbing
Lift disposal onto mounting ring and twist to lock. Connect discharge tube to P-trap, cut to length if needed. Knock out dishwasher drain plug if applicable.
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Test the installation
Turn on breaker and wall switch. Run cold water and turn on disposal. Check all connections for leaks. Run for a minute to verify proper drain flow.
Pro Tips
- Stainless steel sinks create more disposal noise -- consider a model with sound insulation.
- Continuous feed (wall switch) is standard. Batch feed (special stopper) is safer with kids but less convenient.
- Run cold water 15 seconds before and after using the disposal -- cold solidifies grease so it gets chopped instead of coating the drain.
Mistakes to Avoid
- No dedicated electrical circuit -- sharing causes breaker trips.
- Not getting a permit if local code requires one for new circuits.
- Installing on a septic system without checking if the tank handles the extra load.
- Skipping plumber's putty on the flange -- leaks from day one.
When to Call a Pro
New electrical circuit from the breaker panel is an electrician's job in most jurisdictions. Complex drain configurations (double bowl, limited space, galvanized pipes) are best left to a plumber. Many plumbers do the whole install in one visit for $300-$600.
Bottom Line
A first-time disposal is a half-day project. Plumbing is manageable for most DIYers, but the electrical often needs a pro. Budget $150-$300 for the disposal and plan electrical work separately if needed.