With a garbage disposal, the dishwasher’s drain hose clamps onto the disposal’s dishwasher inlet, after you knock out the plug inside it. Without one, it goes to a dishwasher branch tailpiece under the sink.
What’s under your kitchen sink?
Where the hose goes
The disposal’s dishwasher inlet
The drain hose clamps onto the short tube on the disposal’s side, once the knockout plug inside it is out.
On the package: Dishwasher connector kit (Waste King: 7/8 in. hose)
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Start overWhere the hose goes
A dishwasher branch tailpiece
A 1-1/2" sink tailpiece with a side branch for the hose. It replaces the plain tailpiece between the sink strainer and the trap.
On the package: 1-1/2 in. branch tailpiece, dishwasher
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Start overWhere the hose goes
A connector, or the hose’s own cut lines
Some dishwasher hoses have a molded end with cut lines. GE’s fits 5/8", 3/4" or 1" when cut on the matching line. If yours doesn’t, a dishwasher connector kit joins the hose to the inlet.
On the package: Dishwasher connector kit
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Between the dishwasher and the drain, the hose either rises to the underside of the counter (a high loop) or runs through an air gap. Which one depends on your local plumbing code.
Taking out the knockout plug
A new disposal comes with its dishwasher inlet sealed by a plug on the inside. It has to come out, or the dishwasher can’t drain through it.
- Switch off the disposal’s power at the breaker.
- Hold a screwdriver against the plug through the inlet tube and tap it with a hammer until the plug breaks free into the disposal. On a disposal not yet mounted, lay it on its side first.
- Reach in and take out the loose plug; needle-nose pliers help.
- Push the drain hose over the inlet and tighten the hose clamp.
High loop or air gap
Both keep drain water from flowing back into the dishwasher. A high loop routes the hose up and fastens it to the underside of the counter before it drops to the disposal or tailpiece. An air gap is a separate fitting the hose runs through, installed by its maker’s instructions. The codes differ:
| Code | What it says |
|---|---|
| International Plumbing Code (IPC 409.4) | Connect to a wye on the sink tailpiece, the disposal’s dishwasher connection, or through an air break to a standpipe. The waste line has to rise and be fastened to the underside of the sink rim or countertop. |
| International Residential Code (IRC P2717.2) | The drain has to rise to the underside of the counter and be held there before it connects to the disposal or a wye in the sink tailpiece. The sink and dishwasher share a trap at least 1-1/2" in outside diameter. |
| Uniform Plumbing Code areas | Can require a listed air gap fitting. In Minnesota, the plumbing board rules that a home dishwasher has to drain through one. |
Your city or county adopts one of these codes, sometimes with changes, so ask your building department. GE’s installation instructions defer to it too: they call for an air gap or a high loop at least 32" above the floor, depending on local codes, and an air gap whenever the hose connects lower than 18" above the floor or the loop can’t reach 32".
Hose sizes
- Disposal inlets: Waste King’s take a hose with a 7/8" inside diameter. Other sizes need a dishwasher connector kit, such as InSinkErator’s, which has an inlet connector and clamps.
- The dishwasher’s own hose: some have a molded end with cut lines. GE’s fits 5/8", 3/4" or 1" connections; the ribbed part is never cut.
- Length: GE limits the drain hose to 10 feet; check your dishwasher’s instructions for its limit.
Turn off power to the disposal, and to the dishwasher if it’s wired in, at the breaker before working under the sink. Wiring is a separate job: leave it to an electrician if you’re not sure.
Connecting the water line too?
Dishwasher water line