How We Test Garbage Disposals v1.0

Despite being common in the Western Hemisphere, the true capability of garbage disposals are still not well documented. 

On the surface, they are straightforward pieces of machinery: You power the disposal up, flush your garbage down, and wait for it to finish grinding everything to bits. One thing, however, remains vague: what exactly can these machines handle? 

In an effort to put the question to rest, we purchased a number of garbage disposals from different brands and manufacturers just to put them all to the test. We were able to not only make a comparison of the whole collection but also document how well each model works. We dive into their designs and configurations as well to find out what affects their performance.

Overall Ratings

The overall ratings are meant to give our readers a quick look at which products are worth further research. It gives you a broad idea of how smoothly they operate, how well they’re built, and whether or not they are user friendly.

Under each of these three major categories are subcategories to help further differentiate good garbage disposals from the rest. Each subcategory contributes a proportion of points that later on adds up to the main category. Design, for example, is made up of Build Quality, Motor Quality, and Grind Chamber Quality evaluations.

Our Setup

Initially, we intended to run all of our tests in an actual kitchen. That proved impractical, though, due to the restricted space. So our team opted instead for a hand-crafted counter that fits in our lab. It gave us extra room to maneuver during difficult tests.  

The whole counter is made of 24-gauge stainless steel, from the legs to the basin. For a little more weight and stability, we fixed each of the legs with 17.5 pounds worth of cement, totaling 70 pounds added to the setup. Though crude-looking, the whole thing is essentially a portable kitchen counter.

Performance (60%)

All garbage disposals in our collection would undergo a total of three tests that sum up their performance. We tried to tailor each test to highlight certain function-related aspects needed in a typical kitchen. We then rated all candidates on a scale of 1–10 by assessing the data we collected.

1. Scrap Mix Test (50%)

With the Scrap Mix test, we focus on how quickly and how well our collection of food waste disposers would handle a given amount of food. The mix is a combination of materials that are often tossed away, whether it’s scraps from preparation, leftovers after a meal, or old, unwanted food. They range from tough scraps like avocado pits or chicken bones to infamous wildcards like corn cobs or stringy celery.

Aside from variety, we also control the volume of the input load. On one hand, this is done to highlight certain usability aspects of in-sink disposal systems, e.g. their holding capacity; on the other hand, we want to make sure that no product gets an unfair edge on the others and that they all receive their fair share of challenges.

Although the test seems trying at times, it ultimately provides us with useful information. We’re able to rank our collection with confidence based on their different performances, the difficulties that they encounter, and the strengths of their features.

The Scrap Mix Test is important, so it makes up 50% of the Performance rating.

2. Raw Fish Scraps Test (25%)

In case you didn’t know, manufacturers actually recommend grinding animal bones as a way to clean the grind chamber. We included chicken and fish bones in our Scrap Mix test, but they are all cooked. Here, we let the garbage disposals pit their cutters against raw materials.

Fish are bony and tricky to deal with. They have lots of thin bones that may slip through the grinding chamber without breaking much. And you don’t want those pin bones collecting in the plumbing and starting clogs.

The test uses two sets of salmon bones (minus the head) that have had most of their meat filleted and removed. Aside from the bones and tails, there’s also leftover skin and fins, which add another layer to the challenge.

The Raw Fish Scraps Test is responsible for another 25% of the Performance score.

3. Raw Chicken Scraps Test (25%)

Chicken bones are another common type of leftovers in the kitchen. This test is designed on the same ground as the Raw Fish Scraps Test as it takes on manufacturers’ claims about processing animal bones.

Specifically, each product will take a shot at processing the unused chicken thigh scraps left over after deboning. We’re talking bones, skin, tendons, and cartilage. If you’ve tried cutting those when they’re still raw and fresh, you know how tough they can be.

That toughness is the point, though; it helps lay out the true capabilities of in-sink disposal systems, from low horsepower to high. At the same time, any higher-tier shredding features get a solid test as well. 

The Raw Chicken Scraps Test accounts for 25% of the Performance score.

Design (25%)

If performance testing answers the question, “Does it work?” the study of design helps provide a better view on “How does it work?” A garbage disposal with a sturdy grind assembly, a capable motor and quality casing will be able to deliver more satisfying results and minimize extra effort for owners.

1. Build Quality (40%)

Here, we take a close look at the details that make up these machines, both outside and inside. 

For appliances that use powerful motors, a strong, solid construction is very important. Flimsy manufacture poses both malfunction risks and safety hazards. Disposals with decent parts and casings may have better noise insulators and vibration isolators as well. 

Quality is just as important for interior components since the grinding chamber is where the action happens. These machines will only run smoothly if their parts are crafted, lubricated, and assembled with care. 

We consider the build quality assessment to be worth 40% of the Design score.

2. Motor (30%)

To evaluate motors, we focus on the speeds they deliver. Speed is measured in revolutions per minute (RPM), and the higher the RPM, the less likely the chamber is to jam. 

We used a laser tachometer to capture the velocity of the flywheel inside the chamber. Starting off, we run each machine for 30 seconds so the motor warms up. Then, each one is measured a total of five times continuously (when they’re not processing anything) before we average out the results. 

Much to our surprise, the numbers that we collect are often very different from the printed figures. Take the Green Disposall from GE Appliances for example: In contrast to the 2600 RPM listed by the manufacturer, our numbers actually ranged from 4544 to 4615 RPM. The same goes with the Badger 5 from InSinkErator, with 1475-1482 RPM captured as opposed to its advertised 1725 RPM.

Another factor in our motor evaluation is heat. All garbage disposals have fail-safe mechanisms in the form of circuit breakers that trip when their motors overheat. So, it is a real problem if motors generate heat too quickly and cut the power frequently. Not to mention that too much heat can damage internal components. 

Our team allocates 30% of the Design score to the Motor.

3. Grind Chamber (30%)

By any measure, the grinding chamber and the components inside play a pivotal role in how well food waste disposers pulverize garbage.

Surprisingly, close inspection reveals that many of these machines share nearly identical grind assemblies (and motors, for that matter), despite coming from different brands. This partly explains the similarities in the performance data we collected.

We also consider the durability of the internal parts. A garbage disposal made of strong and corrosion-resistant materials — stainless steel, for example — will last longer. Not only that, but tough materials can endure more force and stay sharp for longer.

The assessment of the grind assembly accounts for the final 30% of Design.

Usability (15%)

In the grand scheme of things, there are aspects that may alter users’ experience with these machines other than design quality and performance.

1. Installation (30%)

For DIY folks like us, a simple setup process has great value. 

In the case of garbage disposals, the total weight and the dimensions are worth paying attention to. Of course, a little weight or bulk isn’t necessarily a bad thing, as long as those figures are put to good use and you have the necessary space.

The mounting system is another thing to keep in mind. In our experience, it’s much easier to assemble an EZ Mount system than the more complex 3-Bolt design. You can set up the EZ system using only your hands whereas the 3-Bolt requires at least a screwdriver. You can try installing the 3-Bolt completely by hand if you know what you’re doing, but it may be challenging if you don’t. 

Also, standard versions of some disposals don’t have power cords. You may have to buy a power cord kit separately or recycle a cord from an old appliance and install it yourself. If you’re handy, running electrical wires is not much of a problem. However, it does require certain knowledge and experience. 

Installation amounts to 30% of the Usability score.

2. Ease of Use (40%)

When herding food down the drain where the disposal is grinding, everything that can facilitate the process is a plus. For instance, the holding capacity of each model can determine how much garbage we can haul down the drain and how long we have to keep at it before we can stand back and wait.

Likewise, the distance from the flywheel of the chamber to the bottom of the sink can make a notable difference. The verticality allows for long and hard scraps, such as animal bones and long vegetable stalks, to fit under the splash guard without bouncing out of the drain.

From what we’ve observed, the more horsepower a disposal has, the larger it generally is, both in terms of capacity and depth. So naturally, stronger units are more appropriate for not just tougher but larger and chunkier loads of scraps. 

It’s also worth noting that the mount assemblies, specifically the size of the collar and the use of removable splash guards, can also affect the experience. 

For example, the sink flange of a 3-Bolt assembly is wider than that of an EZ Mount, giving it more flexibility. The same goes with the splash baffle since the sink flange by itself offers more leeway. But when you do remove it, remember to pay attention to random bits flying out of the disposal — especially with tough scraps like bones.

Ease of Use comprises 50% of our Usability score.

3. Smooth Operation (25%)

The overall flow is important to any application. An appliance that runs smoothly makes everything safer and more comfortable. That’s why we are careful to note how things feel when we operate a garbage disposal, from the moment of installation to the very end of our testing processes. 

The aspects that didn’t fall into previous categories find a place here. How easy is the product to assemble and mount? How heavy is it? Can one person install it alone? Do they need special tools? Is it obnoxiously noisy? These are all issues that contribute to the operation rating. 

Because the scoring for this section is mainly based on how we feel about the product, there’s the obvious risk of bias. We do our best to keep things objective by collecting thoughts from the whole testing team rather than from just one appointed reviewer. We also assign this section only 25% of the Usability score.

4. External Unjam Mechanics (5%)

Garbage disposals do tend to jam now and then, so you need a way to clear the problem. If a disposal lets you do so without reaching into the grind chamber, that’s a solid plus.

Jam-clearing features have become less common because contemporary designs are simply more reliable. Nonetheless, we don’t want to overlook good designs when we see them. So, the team agreed that the integration of unjam mechanics that you can access from outside the chamber deserve at least 5% in our Usability score.