Introduction
Garbage disposals eventually wear out — grinding becomes less effective, the motor hums without turning, or the unit starts leaking from the bottom. Replacing one is a manageable DIY project if you are comfortable working under the sink with basic plumbing and electrical connections. In NYC, not all buildings allow garbage disposals (they were actually banned citywide until 1997), so check your lease or co-op rules before installing a new one. If your building permits them, most replacements can be completed in under an hour.
Step-by-Step Instructions
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Step 1 Disconnect Power and Plumbing
Turn off the circuit breaker that powers the disposal. If the disposal is plugged into an outlet under the sink, simply unplug it. If it is hardwired, confirm the power is off with a non-contact voltage tester before proceeding. Place a bucket under the disposal to catch water, then disconnect the discharge pipe from the side of the unit and the dishwasher drain hose if connected. Loosen the mounting ring by turning it counterclockwise — most units have a small wrench or allow you to twist the ring by hand.
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Step 2 Remove the Old Disposal
Support the disposal with one hand while turning the mounting ring to release it from the sink flange. Disposals are heavy — typically 10 to 15 pounds — so be prepared for the weight. If the new disposal uses the same mounting system (most major brands are compatible with the standard three-bolt mount), you can leave the existing sink flange and mounting assembly in place. If the mounting systems differ, remove the snap ring under the sink flange, push the flange up through the drain hole, and clean off the old plumber's putty.
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Step 3 Install the New Mounting Assembly (If Needed)
Roll plumber's putty into a rope and press it around the underside of the new sink flange. Drop the flange into the drain opening from above and press it firmly into the putty. From below, slide on the fiber gasket, backup flange, and mounting ring, then tighten the snap ring to hold everything in place. Tighten the three mounting screws evenly until the flange sits flush and level with the sink surface. Wipe away excess putty that squeezes out around the flange inside the sink.
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Step 4 Connect the New Disposal
If your new unit will connect to a dishwasher, knock out the dishwasher drain plug inside the disposal inlet using a screwdriver and hammer, then remove the plug from inside the grinding chamber. Wire the electrical connection according to the manufacturer's instructions — typically connecting black to black, white to white, and green to ground inside the wiring compartment at the bottom. Lift the disposal into position and turn the mounting ring clockwise until it locks onto the mounting assembly with a click.
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Step 5 Connect Plumbing and Test
Attach the discharge elbow to the side of the disposal with the provided bolts and gasket. Connect the discharge pipe to your drain trap and reattach the dishwasher drain hose to the disposal inlet, securing it with a hose clamp. Turn on the water and check all connections for leaks. Restore power at the breaker, run cold water, and turn on the disposal. It should spin freely without vibration or unusual noise. Run it with cold water for 30 seconds to verify everything is working properly.
When to Call a Professional
Call a plumber if you need to modify the existing drain plumbing to fit the new disposal, if the unit requires hardwiring and you are not comfortable with electrical connections, or if the sink flange is corroded and the mounting assembly cannot be secured. In NYC specifically, call a pro if your building requires a licensed plumber for this type of work (some co-ops and condos mandate this). If you are installing a disposal where one did not previously exist, you will likely need both a plumber and an electrician for the new drain connection and dedicated electrical circuit.
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