How do I keep a garbage disposal clear of clogs?

Grease. The City of Phoenix Water Services says grease is the most frequent cause of sewer problems, and it names grease and roots as the two primary causes of sewer backups and overflows. If cooking grease or oil goes down a drain or toilet, "even when followed by hot water," the city says it eventually cools down, congeals, builds up and hardens, forming a plug in both the home and the city sewer lines.

Georgia Tech's residence hall guidance says the same in a sentence: the most common kitchen drain clogs come from grease buildup in the sink. It adds that hot grease, although liquid when poured, quickly solidifies in the pipes and can trap other debris over time.

Every disposal maker agrees, and the rule is the same in a one-person kitchen and a big building. InSinkErator says to never pour grease or fat into the disposal or drain, and repeats "NEVER put fats, oils, or grease into the disposal" under every series in its food guide.

### What should you do with cooking grease?

Phoenix gives a plain method. Let the grease or cooking oil cool in the cookware, then scrape it into the trash. Georgia Tech suggests saving grease in a plastic or glass container until it cools and then throwing it in the garbage. A paper towel wipe before washing a greasy pan is our own easy add-on. None of this needs a special product.

The makers give a short routine, and nearly every jam or clog starts when someone skips a step.

• Cold water first and last. InSinkErator says to turn on cold water, turn on the disposal, and keep the cold water running for a few seconds after grinding ends. Waste King says to let water and disposal run about 15 seconds after shredding stops. Our page on hot or cold water with a garbage disposal explains why.
• Feed it gradually, and do not pre-load it. InSinkErator says "Do NOT pre-load the disposal" and to feed waste in a little at a time.
• Mix textures. InSinkErator's tip is that mixing food waste with a variety of densities, shapes and textures helps the disposal grind well.
• Keep hard and stringy things out. Moen lists large whole bones, clam or oyster shells, whole corn husks, glass, china, plastic and metal items such as bottle caps and utensils as things not to put in. Waste King's list adds string, cloth, rubber and feathers.
• Leave the stopper in. Waste King says to leave the stopper in place when the disposal is not running, so utensils and other objects do not fall in.
• Pick the right size. A small unit is rated for light use, and heavy scraps can jam it. Our page on what size garbage disposal you need shows how to match it to your household.

### What does a simple routine look like?

This routine is our suggestion, built from the makers' rules and the city's advice.

• Every use: cold water on, scraps in gradually, water on for about 15 seconds after, stopper back in.
• After every greasy meal: wipe the pan, let the oil cool and put it in the trash before you wash up.
• Every few weeks: scrub the underside of the splash guard with a scouring pad, baking soda and warm water, as InSinkErator and Waste King describe, with the power off and your hands out of the unit.
• Every few months: look under the sink for drips at the flange, the discharge and the dishwasher inlet.
• Whenever the sink slows: stop feeding it, and look into the cause the same day.

### What about starchy foods and coffee grounds?

The makers treat them as fine in small amounts. Some institutions say to skip them. Our pages on coffee grounds and on eggshells, rice and pasta give both sides. If your drain is already slow, the cautious answer is the better one.

The disposal is only the first few inches. A clog usually forms in the trap or the branch line beyond it, so a few line habits matter.

Keep water moving. InSinkErator says an odor from the disposal is usually a sign of food buildup caused by insufficient water flow during and after use. The same water flow that keeps the chamber clean carries scraps through the trap.

Watch for slower draining. Phoenix's advice on roots applies to any line: if flows down the drain drop, have a plumber check the line and clear the blockage if necessary. The city says plant roots are the other main cause of sewer backups. They probe a sewer line for any opening, such as a crack or a poorly sealed joint, and once inside they form a ball and block the line.

Know who owns the line. Phoenix says property owners are responsible for cleaning and maintaining the sewer line from the house to the connection with the city main in the street or alley. The city will only repair broken service lines within the public right of way. If your kitchen drain is clear but the whole house drains slowly, see the difference between a main line and a branch line clog.

Clean the trap when you replace a unit. Both Waste King and Moen say that unless your home is new, replacing a disposal is a good time to clean out the trap and drain lines with a drain auger or snake. Our page on how to replace a garbage disposal covers the steps.

Act early, before a slow sink becomes a backup.

1. 1Stop grinding. Feeding more food into a slow line makes the problem worse.
2. 2Tell a jam from a slow drain. A jam hums or makes an odd noise. A slow drain empties slowly while the disposal runs fine. Our page on why a garbage disposal drains slowly explains how to tell.
3. 3Do not pour in a chemical drain cleaner. Waste King and Moen say never to put lye or caustic drain cleaners into a disposal, because they can corrode metal parts, and Moen says the damage is not covered by the warranty.
4. 4Free a jam safely. Cut the power and use a tool, not your hand. Our page on what to do when something falls into a disposal shows how.
5. 5Check the reset. A jam can trip the overload protector, and where the reset button is shows each brand.

Call one if the sink drains slowly with the disposal off, if water backs up into the other side of a double sink, or if the clog returns within days of clearing it. Those point to the trap or the branch line. HQ is licensed and insured, offers 24/7 emergency service for backups, and gives free estimates and upfront pricing.