Plumbing & Irrigation
Plumbing & IrrigationUpdated 10/1/2026

How to Install a Garbage Disposal Under-Sink Unit

Adding or replacing a disposal means setting the sink flange with putty, wiring the unit safely, and connecting the drain plumbing. Done right, it mounts solidly and runs leak-free.

Plumbing & Irrigation
How-To Guides
Difficulty
Advanced
Time
2 hours
Budget
$$
Safety
Medium

Tools needed

  • Flathead screwdriver
  • Channel-lock pliers
  • Bucket
  • Wire connectors

Materials needed

  • Food waste disposer unit
  • Plumber's putty
  • Drain fittings and gasket (included)

Step-by-step

  1. 1

    Cut power to the disposal circuit at the breaker before any wiring.

  2. 2

    Bed the sink flange in a rope of plumber's putty and secure the mounting ring underneath.

  3. 3

    Wire the unit — connect like wires and the ground — inside the bottom plate, or plug it in if cord-equipped.

  4. 4

    Hang the disposal on the mounting ring and twist it to lock.

  5. 5

    Connect the discharge tube to the trap and the dishwasher hose if present, knocking out the dishwasher plug first.

  6. 6

    Restore power, run water, and run the unit to check for leaks at the flange and trap.

Common mistakes

  • • Forgetting to knock out the dishwasher plug
  • • Skimping on putty so the flange leaks
  • • Leaving the circuit live while wiring

Maintenance & next steps

Run cold water during and after grinding, and periodically grind ice to keep it clean.

When to call a professional

For new electrical circuits, switch wiring you're unsure of, or septic-system compatibility questions.

Editor's note: This is instructional content for How to Install a Garbage Disposal Under-Sink Unit. Replace with your own firsthand experience and photos before publishing.
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Related Products

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6 items

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InSinkErator Badger 5 1/2 HP Food Waste Disposer
Oatey Plumber's Putty
DURATECH Aluminum Straight Pipe Wrench
VOTMELL 8 Rolls 1/2 Inch(W) X 520 Inches(L) Teflon Plumbers Tape,Pipe Sealing & Plumbing Thread Tape,PTFE Water Sealant Seal for Shower Head,White
Snappy Trap Universal Kitchen Sink Drain Kit
Channellock 12-Inch Tongue and Groove Slip-Joint Pliers
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InSinkErator Badger 5 1/2 HP Food Waste Disposer
Core item
InSinkErator

InSinkErator Badger 5 1/2 HP Food Waste Disposer

Best for: Grinding food waste at the sink

1/2 HP • continuous feed

Oatey Plumber's Putty
Consumable
Oatey

Oatey Plumber's Putty

Best for: Sealing the sink flange

Stain-free • reusable seal

DURATECH Aluminum Straight Pipe Wrench
Tool
DURATECH

DURATECH Aluminum Straight Pipe Wrench

Best for: Gripping and turning pipe

Lightweight aluminum • adjustable

Snappy Trap Universal Kitchen Sink Drain Kit
Core item
Snappy Trap

Snappy Trap Universal Kitchen Sink Drain Kit

Best for: Replacing a leaking P-trap

Universal • no-measure drain kit

Channellock 12-Inch Tongue and Groove Slip-Joint Pliers
Tool
Channellock

Channellock 12-Inch Tongue and Groove Slip-Joint Pliers

Best for: Loosening slip-joint nuts

12 in • tongue & groove