Garbage Disposals: The Fix and the Septic Question

By the Plumbing Experts Queen Creek team · Updated September 2026

There are not many ways one of these can go wrong, and a couple of them you can sort out yourself over a coffee. Try those before dialling, because there are better uses for a call out fee than watching somebody free a jam with the key that came in your own box.

The rest of this page is about the question people do not ask, which is whether the appliance is a good fit for the property.

What to do first, and what not to touch

A humming motor with a stationary plate means something is wedged in there, not that the unit has died. Kill the power at the wall switch and satisfy yourself it is genuinely off. Underneath the body there is a hexagonal socket, and the little key that came in the box fits it; rocking that key back and forth frees the plate. Underneath as well, usually in red, sits an overload reset. Press it, put the power back on, and try.

Silence is a different diagnosis. No noise at all points at the electrical side, so check the overload reset, then the breaker in the panel, then the wall switch itself, in that sequence.

One absolute rule sits over all of it: nothing goes into that chamber while the appliance is connected to power. Not fingers, not a tool held by hand. Not once, not carefully, not ever.

What not to put down it, and why septic changes things

Plenty of properties in this area, particularly heading out toward the county line, are not connected to a sewer at all. On those, this appliance is not a harmless convenience.

Ground food waste does not vanish. It arrives in the tank and joins the sludge at the bottom, which is the material a pump out exists to remove. Run the appliance heavily and you are loading the tank at a rate nobody sized it for, which pulls the service interval forward. Ignore that shortened interval and solids eventually escape the tank and travel out into the field.

That final step is the one that costs real money, since a tank can be emptied and put back into service while a field mostly cannot. So nobody is telling you to rip the unit out. The sensible position is to treat it as an occasional convenience rather than the default route for scraps, and to set the emptying schedule against what your household actually puts through it rather than against a number from a leaflet.

What should never go in, on any property

Think of it as three groups. Stringy things wind rather than grind, which covers most salad trimmings, corn husks and the outer layers of an onion. Starchy things swell, so pasta, rice and potato peel turn into a paste that coats the pipe instead of leaving it. Hard things simply do not break down, which covers bones, fruit pits and coffee grounds.

Cooking fat belongs in a fourth group of its own, because the appliance has no effect on it whatsoever. Liquid fat leaves the sink exactly as it arrived and hardens wherever it cools, which is usually somewhere you cannot reach without a drain visit. Grinding it first changes nothing except where it sets.

Buying a stronger motor does not exempt any of this. It jams less often and it sends the same material into the same pipe, so the failure simply moves downstream and arrives later. What you put in matters far more than what you paid.

Installation, and the four places it goes wrong

Fitting a disposal is not difficult work, and what goes wrong is almost never the appliance. It is the four connections around it.

Above the unit, the seal at the sink flange has to be made properly or it will weep quietly into the cabinet for months. If a dishwasher drains through the disposal, the inlet plug has to come out first, and leaving it in is the reason a brand new dishwasher sits full of water on its first cycle. Below the unit, the discharge tube has to line up and fall correctly toward the trap rather than being forced into position. And the whole assembly has to be carried by proper mounting rather than by the flange, because a heavy motor swinging on a seal will eventually break it.

The cabinet being open is worth exploiting. Angle stops and braided supply hoses under a sink are consumables that fail without warning, and replacing tired ones while somebody is already under there costs very little compared with a separate visit later.

Hard water, and where it actually shows up

This is one appliance our water treats reasonably kindly. There is nothing inside it with a fine seal to foul and nothing heating anything, so the grinding parts themselves shrug off the mineral content.

The trouble starts once material leaves the unit. Scale on the inside of a waste pipe turns a smooth bore into a gritty one, and ground scraps catch on it in a way they would not in a clean line. That is why kitchen branches here close down sooner than the same pipe would elsewhere. It is a fault of the pipe rather than of the machine, and the two ends of the answer are softening what comes in and, at the other end, properly scouring the line instead of boring a channel through what has built up.

Is a disposal even the right appliance for your household?

Worth asking, because it is treated as a default fitting in a kitchen remodel and it does not suit every household.

It suits a household on the sewer that cooks frequently, generates incidental food waste, and would otherwise be putting small amounts of scrap down the sink anyway. It suits less well a household on septic, a household that composts and therefore has somewhere better for food waste to go, or a kitchen where the drain branch has a history of problems.

The alternative is not exotic. Scraping plates into a bin or a compost caddy before washing keeps food waste out of the plumbing entirely, which is the only approach that removes the problem rather than relocating it down the line. On a property where the kitchen branch has already needed clearing more than once, that is worth considering seriously before fitting a more powerful unit and expecting a different outcome.

Noise, and what it is telling you

Disposals are noisy machines and most of the noise is normal. Some of it is not, and the distinction is easy to learn.

A steady grinding that changes pitch as material clears is the unit working. A sharp metallic rattle is a foreign object, usually cutlery or a bottle cap, and it should be removed with the power off rather than ground away. A hum with no rotation is a jam. A grinding that continues after the chamber should be empty suggests the impeller is catching on something. And a new vibration that was not there before can indicate mounting hardware working loose, which is worth tightening before it works the flange seal.

None of those needs a diagnosis over the phone. They simply tell you which of the earlier sections applies.