TL;DR
The greasy film inside a kibble bin is fat from the food, and it goes rancid over time and taints every new bag you pour on top of it. Empty the container completely, wash it with hot soapy water and a brush, rinse thoroughly, and dry it bone dry before refilling. Do this between bags, not once a year.
Why topping up is the whole problem
Most people pour a new bag onto whatever is left in the bin. That habit is what creates the issue.
Dry pet food carries fat, and fat transfers to the container walls as a thin film. That film oxidizes and goes rancid on a timescale of weeks, not years, and it sits at the bottom of the bin where the oldest food is.
Pouring fresh food onto rancid residue exposes the new food to the same oxidation. It is also why some pets go off a food halfway through a bag when nothing about the food has changed.
The other half of the problem is crumbs. Fine kibble dust settles at the bottom, absorbs moisture, and cakes. Damp caked crumbs are where mold starts.
Keep the food in its original bag
This is the change that does more than any cleaning routine.
Put the whole unopened bag inside the container rather than pouring the kibble in loose. Fold the bag closed and let the container be a rigid, pest-proof outer shell.
Three reasons. The bag is designed as a fat barrier and blocks light and air better than most plastic bins. The container walls stay clean, so there is no film to build up. And the bag carries the lot number and the best-by date, which is the information you need if there is ever a recall or a problem with the food.
Source: Food and Drug Administration guidance on pet food handling and storage
How do you clean a pet food container?
Empty it completely, tip out the crumbs, then wash the inside with hot water and dish soap using a long brush or a cloth, working the corners and the lid seal. Rinse thoroughly with clean water and dry it completely with a towel and air before any food goes back in.
The step-by-step routine
1. Empty it completely. Not almost. The whole point is removing the old residue, and food left in a corner defeats it.
2. Tip the crumbs out. Take it outside and turn it upside down. Kibble dust at the bottom is the oldest and greasiest material in there.
3. Wash with hot water and dish soap. Dish soap is designed to cut fat, and hot water helps it work. Use a long-handled brush or a cloth on a stick for a deep bin.
4. Work the corners and the base edge. The join where the wall meets the floor holds the thickest film.
5. Do the lid and the seal. Rubber gaskets trap grease and crumbs, and a dirty seal is a common source of smell. Pull the gasket out if it is removable.
6. Do the wheels, the scoop and the handles. The scoop lives in the food and gets forgotten. Wash it every time.
7. Rinse thoroughly. Soap residue tastes bad to animals, and some pets will refuse food from a soapy container.
8. Dry it bone dry. Towel first, then leave it open to air for several hours. Any moisture left in a food container encourages mold, which is the one outcome worth being strict about.
Removing a stubborn greasy film
If hot soapy water alone is not cutting it, work through these in order.
Let hot soapy water sit in the container for twenty to thirty minutes before scrubbing. Time does more than force.
Then use a paste of baking soda and water on the film, worked with a cloth or a soft brush, and rinse thoroughly. Baking soda is mildly abrasive and deodorizing, and it is safe for a food container.
For lingering smell after the grease is gone, a dilute white vinegar rinse works, followed by a thorough plain water rinse and a full dry.
What to avoid: chlorine bleach, which is not appropriate for a food storage container and must never be combined with vinegar or any acid, since that releases chlorine gas, nor with ammonia. Also avoid scouring pads, which scratch plastic so it holds grease permanently, and strong solvents, which have no place near food.
Container materials and what they mean
Food-grade plastic bins. The most common. Look for a container sold specifically for food storage, since not every plastic tub is intended for it. Plastic scratches, and scratches hold grease.
Stainless steel bins. The easiest to keep truly clean, since the surface is nonporous and does not hold odor. Wash with soap and water, wipe with the grain, and dry.
Glass and ceramic. Excellent but heavy and breakable, and usually too small for a large bag.
Galvanized metal cans. Fine as an outer shell with the bag inside, which is the better approach anyway.
Whatever the material, an airtight seal matters. Air and moisture are what turn fat rancid, and a bin that does not seal is a bin that goes stale.
Storage conditions matter as much as cleaning
Keep the container somewhere cool, dry, and out of direct sun. A garage that swings from cold to hot causes condensation inside the bin, and condensation plus kibble dust is how mold begins.
Do not store food in a damp basement or against an exterior wall that sweats. Keep the container off a concrete floor, which is colder than the surrounding air.
Buy a bag size your pet finishes in a reasonable time. A very large bag saves money and then goes stale before it is used, which cancels the saving.
If food ever smells sharp, sour, or musty, or if you see mold, do not feed it. Throw it out, wash the container thoroughly, and contact your veterinarian if your pet has already eaten some.
How often should you clean it?
Wash the container between bags, every time, and wash the scoop weekly. That single rule is the whole maintenance schedule.
If you top up rather than emptying, at minimum do a full wash monthly, though changing the habit is the better fix.
Bowls need daily washing, which is a separate and more frequent job. Automatic feeders add a hopper and a chute that hold the same fat film, covered in how to clean an automatic pet feeder, and grooved bowls hold residue in the same way, covered in how to clean a slow feeder bowl.
For the rest of the feeding station and everything else your pet uses, our guide to cleaning pet bowls, bedding, toys and gear keeps the same wash-rinse-dry discipline in one place.
FAQ
How do you get the greasy film out of a pet food container?
Empty it, then let hot water and dish soap sit inside for twenty to thirty minutes before scrubbing with a long brush. For stubborn film, work a baking soda and water paste over it, then rinse thoroughly and dry completely. Dish soap is designed to cut fat.
Should you keep pet food in the bag or pour it into a container?
Keep the food in its original bag and put the whole bag inside the container. The bag is designed as a fat and light barrier, the container walls stay clean, and the bag carries the lot number and best-by date you would need in a recall.
How often should you clean a pet food storage container?
Wash it between every bag, and wash the scoop weekly. If you top up rather than emptying between bags, wash the container at least monthly. Old fat residue goes rancid within weeks and taints the fresh food poured on top of it.
Can you put a pet food container in the dishwasher?
Most are too large, and dishwasher heat can warp thin plastic and distort the lid seal so it no longer closes airtight. Small containers labeled dishwasher safe are the exception. Hand washing with hot soapy water and a long brush works better for a large bin.
Can you use bleach to clean a dog food bin?
It is not appropriate for a food storage container, and it must never be mixed with vinegar or any acid, which releases chlorine gas, or with ammonia. Hot soapy water plus a baking soda paste handles grease, and a dilute vinegar rinse handles lingering smell.
Where should you store a pet food container?
Somewhere cool, dry, and out of direct sun, off a cold concrete floor and away from damp walls. A garage that swings between cold and hot causes condensation inside the bin, and moisture plus kibble dust is how mold starts in stored food.
Feeding stations are a small part of a much larger job. Every home is different, so the real number depends on size, condition, and what you want covered. Get a quote or read more about house cleaning services.