Garbage Disposal Replacement: What to Check Before the Installer Leaves

At iHandyman, we often repair leaks in recently replaced garbage disposals. A new unit is only part of the job—proper installation and testing matter just as much.

Check the sink flange and mounting assembly

Ask whether the installer will replace the upper drain assembly using the parts supplied with the disposal. Reusing compatible mounting hardware can be acceptable, but its condition and seal should never be ignored. A new disposal does not automatically fix an existing leak above it. (InSinkErator Support)

Use the right sealing material

Plumber’s putty is commonly used beneath the sink flange, but the correct material depends on the sink and manufacturer’s instructions. Some installations require a gasket or compatible silicone instead. Silicone is not automatically wrong—using an unsuitable material is. (Oatey)

A white ring around the flange is not proof of quality. Excess putty should be cleaned away after installation. (Oatey)

Don’t overlook the dishwasher connection

When a dishwasher drains through the disposal, its inlet plug must be removed. Traditional knockout plugs should be removed before mounting, and the loose piece retrieved from inside. Other designs use a different removal method, so follow the model’s instructions. Leave the plug intact when that inlet is unused. (InSinkErator Support)

Test before accepting the work

Ask the installer to check the flange, drain connections, and dishwasher connection for leaks, then demonstrate operation. Don’t accept “the motor runs” as the entire inspection. Request a dishwasher drain test, too, when connected. (InSinkErator Support)

Our Sacramento replacement price

iHandyman charges $150 for labor on a like-for-like replacement requiring no drainpipe modifications. The disposal is purchased separately.

For an identical replacement, ask for a clear explanation before approving extra plumbing charges. Existing damage may justify additional work—but the reason and price should be explained upfront.

Know what is being replaced, agree on the price, and make sure everything is tested.