A handy homeowner can swap one disposal for another. A licensed plumber is the right call when the sink drain, dishwasher hookup or a first-time install is involved, and a licensed electrician handles any new switch or outlet.
Permit rules vary, so ask the Firestone building division before you start. Most installs are one trade, but a first-time unit often needs two.
Three ways to get it installed
Each route fits a different starting point. Find the row that matches yours.
| Who | Best fit | Watch out for |
|---|---|---|
| You, as a DIY job | Replacing an existing disposal with a similar one. | Stripped mounting parts, a missed dishwasher knockout, a leak under the sink. |
| Licensed plumber | First-time install, new drain parts, dishwasher hookup problems. | Needs a clear price and a described scope before work starts. |
| Licensed electrician | No outlet under the sink, new switch, or damaged wiring. | Wiring added without a plan for the circuit. |
| Plumber plus electrician | New disposal where there was none and no outlet. | Scheduling two visits, so ask who goes first. |
Swapping like for like is the easiest case. Everything else adds a step.
The two jobs hidden inside one install
A disposal has a plumbing side and an electrical side. The plumbing side is the sink flange, the mounting ring, the drain connection and the dishwasher hose. The electrical side is how it gets power and how it turns on.
Many disposals plug into an outlet under the sink, and some are hard-wired to a junction box. Either way, a wall switch or an air switch controls it. If the cabinet has neither an outlet nor a switch, call an electrician before you buy the unit.
The dishwasher knockout is the step people forget
The dishwasher drain tube connects to a small port on the disposal. On a new unit that port is capped by a plastic plug called a knockout. If you leave it in, the dishwasher cannot drain and water backs up into the machine. Remove it with a hammer and a screwdriver, then fish out the plug so it does not jam the grinder.
What a typical install involves
This is the order a plumber usually follows. Your job will vary by sink and model.
- Shut off power and water access.Unplug the old unit or turn off the breaker. Clear the cabinet under the sink.
- Remove the old unit.Loosen the drain connections, twist the unit off its mount and disconnect the dishwasher hose.
- Set the new mount.Seat the sink flange with plumber's putty, attach the mounting assembly and tighten it evenly.
- Hang the unit.Lift it onto the mount, lock it in place, and connect the drain and dishwasher hose.
- Wire, test and leak-check.Restore power, run cold water, and watch every joint for drips.
Do it yourself or hire a plumber
Think about how the job will go if something does not fit.
A reasonable DIY swap
- Same size and mount style as the old unit.
- Existing outlet and switch work fine.
- Dishwasher line is already connected.
- You are comfortable working under a sink.
Better left to a licensed plumber
- First disposal at this sink.
- Old drain pipe is corroded or crooked.
- Dishwasher line has no high loop.
- The sink flange will not seal or the sink is stone or composite.
Questions to settle before you buy
A few minutes of checking prevents a second trip to the store.
- Is there power under the sink?Look for an outlet or a junction box and note where the switch is.
- What is the sink made of?Some materials need a specific mounting approach, so read the instructions.
- Which mount does the old unit use?Mounting systems differ, and a mismatch means rework.
- Does the dishwasher connect here?Plan to open the knockout if it does.
- What is the drain layout?A single-bowl and a double-bowl sink need different tailpiece arrangements.
Leaks and clogs after a fresh install
The most common problem after an install is a slow drip at the flange or at the drain connection. Dry every joint with a paper towel, run water for a minute, and touch each one. A drip at the top usually means the putty or gasket is not seated. A drip at the side means a connection needs tightening.
Slow drainage after a new unit often points to a crooked tailpiece or a trap that was reassembled out of line. It can also mean the old drain was already partly blocked. Do not run the disposal to push through a clog. Stop and have it cleared.
Choosing a size without overbuying
Disposals come in different motor sizes. A larger motor grinds tougher scraps and runs a little smoother, but it needs more cabinet room and a sink that can support the weight. For a household that mostly scrapes plates, a mid-sized unit is plenty.
Bring the cabinet measurements and the sink type when you call. A plumber can tell you quickly whether a bigger unit will fit under your sink and whether the trap can be arranged around it.
Permits and who signs off on them
Colorado licenses plumbers through the state, and you can verify one with the DORA online lookup. Whether a disposal swap needs a permit depends on the job and the town, so ask the Firestone building division at the Town's Planning and Development office. They can tell you what applies to a like-for-like swap, a new drain or a new circuit.
If a permit is required, the plumber or electrician on the job should be listed on it. Ask to see the license number and confirm it is active before work starts. The base code licensed plumbers work to is the 2021 International Plumbing Code (IPC) as adopted in Colorado, and the Firestone building division enforces it through inspections, so ask what it will check on your drain and dishwasher connection.
What to expect when a plumber comes
A plumber will look at the sink, the cabinet and the drain, then explain what is needed and give you a clear price before work starts. If wiring is missing, the plumber will say so and tell you the electrician's part of the job. Our plumbing installation work covers new disposals and sink reconnections.
If your existing unit hums, jams or leaks and you are weighing replace versus fix, garbage disposal repair can sort that out. Sometimes a jam reset or a new seal is all it needs.
What this means in Firestone, CO
Most Firestone homes were built after 2000, and some kitchens already have the wiring in place. Look under your sink for an outlet or a switch before you assume an electrician is needed.
Permit rules vary by town, so ask the Firestone building division if you live in town, or the Weld County Building Department if you are in unincorporated rural land near Mead. Neighbors in Frederick should check with Frederick instead.
Questions homeowners ask
Yes, if you are swapping a similar unit and the wiring is already in place. A first-time install or a drain that needs reshaping is better handled by a plumber.
Only if there is no outlet or switch, or the wiring is damaged. A plumber can handle the water side. Ask a licensed electrician to add or change anything on the circuit.
The knockout plug in the dishwasher port may still be in place. Removing it opens the path so the dishwasher can drain.
It depends on the town and the scope. Ask the Firestone building division what applies before you start.
Unincorporated properties fall under the Weld County Building Department. Ask them which rules apply to your address.