How to Install a Garbage Disposal
Replace a worn-out disposal or add one for the first time. This intermediate guide covers electrical connections, plumbing hookups, and mounting — all in 60-90 minutes with basic tools.
Repair & Refinish Team
Published November 10, 2025 · Updated February 15, 2026
What You'll Need
- Plumber's putty or mounting gasket
- Screwdriver (flathead and Phillips)
- Tongue-and-groove pliers
- Hex wrench (included with disposal)
- Bucket and towels
- Wire strippers (if hardwiring)
- Hammer
- Garbage disposal unit with mounting hardware
- Power cord (if not included)
- Discharge tube and gasket
- Plumber's putty
- Wire nuts (if hardwiring)
- Dishwasher drain connector (if applicable)
Cost Estimate
Budget
$80
Mid-Range
$150
Premium
$250
A plumber charges $250-$500 for disposal installation. DIY you pay only for the unit ($80-$250) and possibly a power cord ($10).
Step-by-Step Instructions
Disconnect Power and Remove the Old Disposal
Step 1 of 8Turn off the circuit breaker for the disposal. If replacing an existing unit, unplug it from the outlet under the sink (or disconnect the hardwired connection). Place a bucket under the disposal. Disconnect the discharge pipe and dishwasher drain hose. Support the disposal with one hand and turn the lower mounting ring counterclockwise to release it from the mounting assembly. The unit will drop free — it's heavy (8-15 pounds), so be ready.
Always disconnect power before working on a disposal. Even with the switch off, the outlet may still be live if it's on a different circuit.
Remove the Old Mounting Assembly (If Incompatible)
Step 2 of 8If your new disposal uses the same mounting system as the old one (most InSinkErator models share a mount), you can reuse it. If not, loosen the three mounting screws, remove the snap ring from inside the sink drain opening, and push the flange up through the sink hole. Clean all old putty from around the drain opening with a plastic scraper.
Most disposals use the InSinkErator-style EZ Mount or a 3-bolt mounting system. Check compatibility before buying — reusing the existing mount saves 30 minutes.
Install the New Mounting Assembly
Step 3 of 8Roll a pencil-thick rope of plumber's putty and press it around the underside of the new sink flange. Push the flange down through the drain hole from above. From below, slide the fiber gasket, metal backup ring, and mounting ring onto the flange. Install the snap ring into the groove on the flange — it holds everything in place. Tighten the three mounting screws evenly until the flange sits flush and putty squeezes out slightly. Wipe away excess putty from above.
Tighten the three mounting screws in a star pattern (like lug nuts) to ensure even pressure and a leak-free seal.
Attach the Power Cord
Step 4 of 8If your disposal doesn't have a pre-attached power cord (most don't), remove the electrical cover plate on the bottom. Thread the power cord through the strain relief fitting. Connect the black wire to black, white to white, and green to the green ground screw using wire nuts. Tighten the strain relief to secure the cord. Replace the cover plate. If your setup is hardwired, make the same connections with the house wiring.
Ensure the breaker is OFF before making any electrical connections. Double-check that wire nuts are tight and no bare copper is exposed outside the nuts.
Knock Out the Dishwasher Plug (If Needed)
Step 5 of 8If you have a dishwasher that drains through the disposal, locate the dishwasher inlet on the side of the disposal. Use a hammer and screwdriver to knock the plastic plug inward. Reach inside the disposal and remove the loose plug — if you leave it inside, it will cause a jam. Connect the dishwasher drain hose to this inlet with a hose clamp.
Always remove the knockout plug from inside the disposal after punching it out. A plug left inside will immediately jam the grinder.
Mount the Disposal
Step 6 of 8Lift the disposal and align the three tabs on the unit with the mounting ring under the sink. Turn the lower mounting ring clockwise until all three tabs lock into place — you'll hear and feel them click. Some units come with a wrenchette tool to tighten the ring the final quarter turn. The disposal should hang securely from the mounting assembly with no wobble.
Connect the Discharge Pipe
Step 7 of 8Attach the discharge tube to the side outlet on the disposal using the provided gasket and flange. Connect the discharge tube to your sink's P-trap using a slip joint connection. Make sure the discharge tube slopes downward from the disposal to the P-trap — water needs to flow by gravity. Hand-tighten all slip joints, then snug with pliers (quarter turn past hand-tight).
If the discharge tube is too long, cut it with a hacksaw. If it's too short, buy a longer tube or an extension — don't force a connection that doesn't reach.
Test for Leaks and Proper Operation
Step 8 of 8Turn the water on and let it run through the disposal for a minute. Check every connection for leaks: the sink flange, the mounting assembly, the discharge tube, and the dishwasher hose. Tighten any dripping connections. Turn on the circuit breaker and flip the disposal switch. Run cold water and feed small amounts of food waste to test grinding. The disposal should grind smoothly without excessive vibration or noise.
Always run cold water when using the disposal. Cold water solidifies grease so the disposal can grind it up. Hot water keeps grease liquid, letting it coat the drain pipe downstream.
Recommended Products
The best-selling disposal in America. 1/2 HP motor handles everyday food waste. Galvanized steel grind components. Quick-lock mounting system. 2-year warranty.
Two-stage grind technology handles tough scraps. SoundSeal technology for quiet operation. Stainless steel components. 4-year warranty. Worth the upgrade.
Pre-wired 3-foot power cord with grounded plug for InSinkErator disposals. UL-listed. Includes strain relief fitting. Required if your disposal doesn't come with a cord.
Continuous feed disposal with permanent magnet motor. Stainless steel impellers. EZ Mount for easy installation. Lifetime limited warranty. Great budget alternative.
Affiliate Disclosure: We earn a small commission when you buy through our links at no extra cost to you.
Tips & Warnings
- Run cold water for 15 seconds before and after grinding food. This flushes ground particles through the drain line.
- The InSinkErator Badger 5 is the best-selling disposal for a reason — reliable, affordable, and compatible with the most common mounting system.
- Never put fibrous foods (celery, artichokes, corn husks), grease, pasta, rice, or coffee grounds down the disposal. These items clog the drain or jam the grinder.
- If the disposal jams, turn it off, use the hex wrench in the bottom of the unit to manually turn the grinder, then press the reset button.
- Freshen a smelly disposal by grinding ice cubes and a lemon wedge with cold water running.
- Always disconnect power at the breaker before working on the disposal's electrical connections.
- Never put your hand inside a disposal — even when it's off. Use pliers or tongs to retrieve dropped items.
- If you don't have a switched outlet under the sink, hire an electrician to install one. Running new electrical is not a beginner project.
Frequently Asked Questions
Found this guide helpful?
Get more repair tutorials and maintenance checklists delivered to your inbox every week.
Related Guides
A clogged kitchen sink is one of the most common household headaches. Learn how to clear it quickly using a plunger, drain snake, or simple baking soda and vinegar — no harsh chemicals needed.
Upgrade your kitchen with a new faucet in about an hour. This intermediate guide covers removing the old faucet, installing the new one, and connecting the supply lines without leaks.
Stop that constant running sound and save up to $200 per year on your water bill. This beginner-friendly guide covers the three most common causes and how to fix each one in under 30 minutes.