A Homeowner’s Guide to Sizing Garbage Disposals

According to Consumer Reports, more than half of U.S. households have a garbage disposal. They’re great appliances for reducing waste, increasing convenience in the home, and counteracting the harmful emissions of landfills.

If you’re buying a garbage disposal for the first time, however, you might have a few questions about installation. Chief among them would be size. How do you measure your sink? Do you need to measure pipes and flanges, too? What size garbage disposal do you actually need for your house?

How a Garbage Disposal Works

Before we get into sizing, it’s important to understand the basic anatomy of a garbage disposal and how it works.

A garbage disposal can be described as a large metal canister that fits within and beneath your sink. It consists of grinding chambers, also called hoppers, that intercept food scraps and pulverize them into small bits before washing them back down your pipes.

Many people think that garbage disposals work like blenders, but this isn’t actually the case. They don’t have blades. Instead, they have grinding wheels that become shredders when the bottom metal plate of the chamber starts rotating. This is called the flywheel, and as it spins, it generates a centrifugal force that sends food debris slamming into the grinding wheel. This process shreds them and makes them small enough to pass through the pipes.

Another critical part of garbage disposals is their impellers. They act like “teeth” when the flywheel starts moving, increasing the pressure and water flow within the chamber. Impellers serve a similar purpose in washing machines if you’re familiar with that technology.

Here are the most important pieces of a garbage disposal:
  • Motor
  • Grinding chambers
  • Grinding ring
  • Impellers
  • Flywheel

There are other parts and pieces as well, including drain flanges, mounting rings, and optional accessories such as dishwasher inlets. However, the ones listed above are the most crucial in terms of sizing. You’ll understand why as you continue to read on.

Measuring Your Sink

The first step to sizing a garbage disposal is figuring out how much space is physically beneath your sink. You’ll need to break out the measuring tape and determine the length, width, and height of its free space.

Note the word “free space.” This is different from the entire length and width of the cabinet. Some cabinets have pipes that can’t be moved, and you can’t cut your garbage disposal in half to make it fit around them. Instead, your garbage disposal will need to fit within the largest available amount of free space.

The good news is that garbage disposals are available in a wide variety of sizes, so you should be able to find something that works for you.

Determining Your Power Needs

Garbage disposals run on a motor, and the power of this motor is measured in horsepower (hp). The higher the horsepower, the more powerful the unit.

What does power mean in the context of garbage disposals? It usually refers to rotations per minute (RPM), which can be as many as 2,800 RPM in high-efficiency models. However, it can also mean a finer grind or a capacity for handling more food scraps at once.

As for how much horsepower you’ll need in your own garbage disposal, that depends on the size of your household.

Here’s the power ladder:
  • 1/3 hp
  • 1/2 hp
  • 3/4 hp
  • 5/8 hp
  • 1 or 1+ hp

For individuals and couples, a 1/3 hp garbage disposal is usually enough. It’s the smallest and cheapest model, and its grinding power is just fine for minimal food scraps.

Families will want to upgrade to 1/2 or 3/4 hp, which is better suited for handling larger quantities of food multiple times per day. Large families might want to upgrade even further to 5/8 hp.

Garbage disposals with 1 hp or higher are usually reserved for restaurants, hotels, and other commercial buildings, but there are also circumstances where they can be advantageous to residential homeowners. For example, very large families or families that do a lot of cooking for their neighbors or communities might enjoy the high-powered efficiency of a 1 hp garbage disposal. Small business owners who cook or bake out of their homes can also benefit from restaurant-quality appliances.

One last thing to remember is that the size of a garbage disposal usually correlates to its amount of horsepower. In other words, a larger amount of horsepower means a larger garbage disposal unit. The 1/3 hp models are the smallest, while the 1+ hp models are the biggest.

Other Sizing Factors for a Garbage Disposal

Cabinet space and horsepower are the two most important aspects of sizing a garbage disposal. However, there are a few other things to keep in mind as well.

The first is the volume capacity of the grinding chamber. In layman’s terms, this is how much food can fit into the garbage disposal without interfering with the grinding process. Pay attention to the second part of that sentence: Some homeowners stuff their garbage disposals so full that the grinding wheel isn’t able to do its job properly. This is when you get clogs!

The average garbage disposal can hold anywhere from 20-30 ounces of food without difficulty. Larger, high-efficiency units can hold upwards of 40 ounces.

Another sizing element to consider is the size of your sink drain and drain pipe. These connect directly to the garbage disposal, so all of them need to be compatible with each other. While most homes have a standard size for sink drains and pipes, custom-built houses, taps, or vanities might have different measurements. It’s something to check before buying a garbage disposal.

Installing a New Garbage Disposal

It usually only takes an hour or two to install a new garbage disposal. For the best results, you’ll want to have it professionally done by a plumber. They can ensure that everything gets fitted correctly for optimal food grind, water flow, and pipe drainage. They’ll also better understand safety precautions for dealing with an electrical household appliance like a garbage disposal.

The installation process starts by preparing the space underneath the sink for the new unit. If you’re replacing an older model, the plumber will have to remove it first, potentially shutting off circuits and disconnecting old drain connections.

The next step is installing the new unit. This involves inserting the drain flange, installing the mounting ring assembly, connecting the power cord, mounting the disposal unit, and hooking up all necessary pipes and inlets.

Last but not least, you’ll want to ask the plumber to perform a test run before they leave. You never know when a fastener or fitting will need to be tightened to prevent a leak.

Building the Kitchen of Your Dreams

If you have any further questions about garbage disposals, contact We Care Plumbing, Heating and Air today. We’re experts at everything from household appliances to HVAC networks and systems. Whether you’re in Murrieta, Temecula, or Orange, we’d be glad to help you build, renovate, or retrofit your property to your exact specifications.

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