Before the visit
Clear out the cabinet under the sink so the plumber can reach everything. Have the new unit on hand if you bought it, along with its box and paperwork. If you have not chosen one, ask the plumber what they would bring and what it would cost, in writing.
It also helps to know how the old disposal gets power, whether a dishwasher drains into it, and whether the sink has drained slowly lately. A slow drain is worth mentioning, because a new disposal will not fix a clogged kitchen line.
The installation, in order
Power off and verify
The circuit is turned off and the unit is unplugged or the wiring is confirmed dead before anything is disconnected.
Remove the old unit
The drain elbow and dishwasher hose come off, the disposal is turned off its mount, and the electrical connection is removed.
Replace the flange
The old flange is lifted out, the sink opening is cleaned, and the new flange is set in fresh putty or a gasket and clamped from below.
Prepare the new unit
The power cord or wiring is attached, and if a dishwasher will drain into it, the knockout plug is removed and the disc retrieved.
Hang and align
The unit is lifted onto the mount and turned so the drain outlet lines up with the trap. Drain pieces are adjusted if the height changed.
Reconnect
The drain elbow, trap and dishwasher hose are connected and tightened.
Test
The sink is filled and drained, the disposal is run with water, the dishwasher runs a drain cycle, and every joint is checked for drips.
Before the plumber leaves
- The disposal starts, runs smoothly and stops with the switch.
- No drips at the flange, the elbow, the trap or the dishwasher hose with a full sink draining.
- The dishwasher drains fully into the new unit.
- The reset button and hex socket on the bottom are reachable.
- The old unit is hauled away or left for you, as agreed.
- You have the new unit's paperwork and the written invoice.
What drives the cost
- Unit
- Supplied by you or the plumber, and its size and features
- Drain changes
- Needed if the new outlet height does not match the old
- Electrical
- Cord, outlet, switch or hardwire work
- Surprises
- Corroded traps, damaged flanges or a slow drain line
Questions to ask
- Will you replace the sink flange or reuse it?
- Will the drain need to be adjusted for this unit?
- Will you remove the knockout plug and test the dishwasher?
- Is haul-away of the old unit included?
- What is your CSLB license number?
Common questions
Does a new disposal need a new flange?
Not always, but most new units come with one and replacing it gives a fresh seal. Ask what the plumber plans.
Will the new unit fit where the old one was?
Usually close, but height and outlet position differ between models, so the drain may need small changes.
Should I run the dishwasher right after install?
Yes, ideally while the plumber is still there, to confirm it drains and nothing leaks.
General information for Fullerton, not a quote or professional advice. In an emergency, call 911.