How We Test Garbage Disposalsv1.0

Be Nguyen
Be Nguyen
Lap Vo
Lap Vo
Head of RTR
Nguyen Ntk
Nguyen Ntk
Visual Specialist

Despite being widely owned in the Western Hemisphere, the true capability of garbage disposals are still somewhat unknown. 

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

In an effort to put the question permanently 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 worked. We dive into their designs and configurations, as well, to find out what either pulled or pushed their quality of use.

Overall Ratings 

The overall ratings are meant to give our readers their very first ideas of the products they’re researching—ideas about how well they operate, how sleek they are built and whether or not they are user friendly.

In the case of garbage disposals, these ratings are calculated from 60% of Performance, 25% of Design and 15% of other aspects that may have an effect on the experience.

Under these three major categories, there are subcategories to help further inspect certain areas. Each subcategory offers a proportion of points that later on adds up to the main category. Design, for example, is constituted by the evaluations of Build Quality, Motor Quality and Grind Assembly Quality.

Our Setup

Initially, we intended to run all of our tests in an actual kitchen. Our attempt, in the end,  was rendered impractical due to space restrictions and the complexity of some particular processes. Instead, our team opted for a hand-crafted counter that fits in our lab as a solution for difficult tests, which often take advantage of extra room. 

The whole counter is made of 24-gauge stainless steel, supported by 1 916 in 1 916 in legs and stabilized by 1 316 in 1 316 in stretchers. Picture a portable kitchen counter with a full metal frame, if you may. 

On its own, the counter was already quite heavy, but the team decided for more weight as to further ensure stability and limit the margin of error. We mixed some cement mortar and fixed counter’s feet with four solid base risers. 

These risers help add significant weight (around 70 lbs) to the counter and raise the whole thing up by roughly 7 in. The feet are also partly cemented in the mortar, making them even studier than before.

For simpler tests, we stuck to the kitchen and its limits. Though the space was not in favor of our recording process, its conditions best resembled that of a normal home.

Performance (60%)

All garbage disposals in our collection would undergo a total of three tests that sum up performance. We want to shape 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.

Performance tests consist of Scrap Mix (50%), Raw Chicken Scraps (25%), and Raw Fish Scraps (25%).

1. Scrap Mix Test (50%)

With the Scrap Mix test, we focus on how fast 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 tossed away, whether it’s scraps during preparation, leftovers after a meal, or old food. They range from tough scraps—like avocado pits or chicken (thigh) bones—to infamous wildcards—like corn cobs or stringy celery.

Aside from variety, we also target and control the volume of the input load, on one hand, 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 has the edge on the other and that they all receives their fair share of challenges.

Although the test seems too trying at times, it comes out successful in the end as it produces useful information for the scoreboard. 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 takes up 50% of the Performance rating for its importance.

2. Raw Chicken Scraps Test (25%)

In case you didn’t know, grinding animal bones is recommended by manufacturers as a way to clean the grind chamber. You may notice that we have chicken and fish bones in our Scrap Mix test, but they are all cooked. Here, we let the garbage disposals try their shredders against raw materials.

Specifically, the selected products will take turns processing the leftovers of chicken thighs after they’ve been deboned, or rather defleshed; we’re talking bones, skin, tendon, and cartilage. If you’ve tried cutting those when they’re still raw and fresh, you know how tough and relentless they can be.

Nonetheless, as difficult as the test can get, it helps lay out the true capabilities of in-sink disposal systems, from low horsepower to high. At the same time, features meant to enhance shredding capability on higher tier models are tried, as well.

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

3. Raw Fish Scraps Test (25%)

Next to chicken bones, fish bones are another common type of leftovers in the kitchen. Except for the choice of ingredient, this test is designed on the same premise as the Raw Chicken Scrap Test as it takes on manufacturers’ claims about processing animal bones.

Unlike chickens, fish are much more bony and, therefore, trickier to deal with. They have lots of thin bones that can escape the grinding chamber without breaking much; they can be the pin bones or the bones that break off from the spine. 

The test uses two sets of salmon bones (minus the head) that have had most of their meat fileted. 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 Performance.

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 the work needed from users.

Design consists of Build Quality (40%), Motor Quality (30%) and Grind Assembly (30%).

1. Build Quality (40%)

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

For appliances that use motors with abundant power, rigidity in construction is something we should all keep in mind. Flimsy build, for example, not only poses a risk of malfunction but also one of hazard. A disposal with decent parts and casing reaps the benefits of heat insulation and vibration isolation, too.

The same goes with whatever inside the grind chamber, where most of the action happens. Whether or not the grinding parts are crafted, lubricated, and assembled with care, and how secure it is connected to the motor do predict how smoothly a disposal will run. 

That’s why build quality is considered in scoring designs, and why it takes up 40%.

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 chance there is for the grind chamber to jam.

We used a laser tachometer to capture the velocity of the flywheel inside the chamber to tell how fast the motor is spinning. Starting off, we allow each machine 30 seconds to warm up their motor. 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 notably different from the printed figures, across our whole collection. Take the Green Disposall from General Electric for example: in contrast to the 2600 RPM given by its manufacturers, our numbers actually range from 4544 to 4615 RPM. The same goes with the Badger 5 from Insinkerator, with 1475-1482 RPM captured as opposed to 1725 RPM said in its product description.

Another factor concerning the motor is the subsequently generated heat. All garbage disposals have a fail-safe in the form of circuit breakers that trip when their motors overheat. So it is a real problem if motors generate heat too fast, which results in more frequent power cutoff and higher risks of internal damage.

Given how much a motor may affect the quality of use, the team allocates 30% of Design to Motor. 

3. Grind Chamber (30%)

By any measures, the grinding components play a pivotal role in how well disposals dispose of garbage and they should be, of course, taken into account.

Surprisingly, close inspection reveals that a portion of these machines share the same design for the grind assembly and even for the motor to some extent, despite the fact they come from completely different brands. This partly explains the similar data we collated from evaluating performance. 

We also consider the durability of the internal parts. A garbage disposal that makes use of strong and corrosion resistant materials—stainless steel, for example—is more sustainable when time is factored in. Not only that, quality material can endure more force and stay sharp for longer.

The assessment of the grind assembly holds the final 30% of Design.

Usability (15%)

In the grand scheme of things, there are other aspects that may alter users’ experience with these machines other than how good they are at shredding scraps and how well they’re built.

Usability assesses Installation (30%), Ease of Use (40%), Smooth Operation (25%) and the integration of Unjam Mechanics (5%).

1. Installation (30%)

For us DIY folks, it would be remiss not to count all that contribute to an effortless setup. 

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

Other than that, there’s the mount. From experience, it’s much easier to assemble the EZ mount than the 3-Bolt as the 3-Bolt has a considerably more complex design. You can set up the EZ using only your hands, whereas the 3-Bolt requires at least a screwdriver with an appropriate head (depending on which brand). You can try installing the 3-Bolt completely by hand if you know what you’re doing, but it can be challenging if you don’t.

Also, keep in mind that models compatible the 3-Bolt mount connect to the assembly via a collar piece unattached to the body, while EZ-mount models latch onto its mount directly from the body; in other words, you’ll have to turn the whole body to lock in instead of just the collar. Subsequently, heavier bodies that use the EZ assembly are relatively harder to install.

Installation amounts to 30% of Usability

2. Ease of Use (40%)

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

Likewise, the distance from the flywheel of the chamber to the bottom of the sink can make a notable difference, as well. The verticality allows for long and hard pieces of scraps, such as animal bones and long stalks of veggies, to fit under the splash guard without poking up and splashing.

From what we’ve observed, the more horsepower a disposal has, the more likely it is to offer extra capacity and verticality. So naturally, stronger units are more appropriate for not just tougher but larger and chunkier loads of scraps. 

It’s also worth keeping in mind that the mount assemblies, specifically the size of the collar and the integration 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, allowing more flexibility. 

The same thing goes with the removable splash baffle since the sink flange by itself offers more leeway. But remember to pay attention to random bits flying out of the disposal, especially with tough scraps like bones, when you do remove the baffle.

Ease of Use decides 40% of Usability.

3. Smooth Operation (25%)

The overall flow is an important aspect to any application. Household appliances are no exception; if any, it matters even more in the context of a home as comfort and safety are concerned. That’s why it’s an objective to note how things feel when we operate a garbage disposal, from the moment of installation to the very end of our testing processes. 

Besides aspects that are targeted in the tests, how easy it is to assemble the mount and secure the machine, whether it’s too heavy to install by one person or if it needs any tool during the process, the noise level of operation when there is scraps versus when there isn’t, etc. are things that contribute to the flow.

Because the scoring for this section is mainly based on how we feel about the product, there’s the obvious risk of bias. But we keep things objective by collecting thoughts from the whole testing team rather than from the appointed reviewer alone. We also associate this particular section with a suitable proportion of Usability, which is 25%.

4. External Unjam Mechanics (5%)

Featuring some way to unjam the motor is fundamental for garbage disposals because they are, by nature, prone to jamming. And if a disposal lets you do so without reaching into the grind chamber, it’s a solid plus.

Overtime, such mechanics have seen less and less use thanks to how contemporary designs help avoid such an incident. Nonetheless, we don’t want to overlook good designs when we see one. So the team agrees that the integration of unjam mechanics from outside the chamber deserves at least 5% in Usability.

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