January 21, 2012

What to look for when shopping for a new garbage disposal

If your kitchen drain tends to clog when you use your garbage disposal, it's not your fault, nor the fault of your plumbing.   More likely, the fault lies with the galvanized steeldeep inside your disposal, where they figure nobody will ever look!
It took me a long time to figure out that my galvanized-steel disposal was causing my kitchen drain to clog.  I guess I never gave my garbage disposal any thought, unless it stopped running, or started leaking.   

Actually, even then I didn't give it much thought.  I just replaced it with something cheap with a hefty amount of horsepower.   I figured that was important, because every disposal in the store has a huge horsepower sign plastered on the side.

And that strategy seemed to work.  Every disposal I ever bought was unstoppable, with plenty of power to grind up everything.  (Except maybe silverware, which disposals tend to snack on like they're nachos.)

Unfortunately, my kitchen drain is not unstoppable.  So after a while, the time would come when I had to be careful how fast I fed the disposal, or the drain would clog.   My plumber said the problem was that our house had "old pipes".  Seemed reasonable.  So I learned to be careful to not put too much garbage in the disposal at one time.  And I learned how to take apart the sink trap apart to pull out the clog.

Eventually though, I began to suspect that maybe the age of the pipes wasn't the problem.   I mean, why is it the drain never clogged when the disposal was new?    

Ignoring the "wisdom" of my plumber, I set out to look into the situation myself.  Literally.   I got a flashlight and peered into the mouth of the disposal.   Hah!  Just as I expected, there was yucky stuff in there. 

What I didn't expect, was how corroded the inside of of the disposal was, given that it was scarcely two years old, and still bright and shiny on the outside!

Here's a picture of the inside of this "corrosion resistant" disposal:

See that hole (circled in red) on the left?  That's where the garbage is supposed to go into the drain, only after it's been ground into tiny bits small enough to pass through the pipes without issue.

Well, that hole isn't supposed to be there!  There should be a metal-toothed shredder ring there, guarding the exit port.  But the shredder-ring teeth -- and most of the turntable -- have rusted away.   So instead of holding all the garbage until it was properly ground up, this rusted hulk let huge chunks out that clogged up the drain.

Yet, on the outside, the disposal looks nearly new!   And that's what is so mean about putting galvanized-steel parts on the inside, where they have no business being.  The outside can look almost new,  and the horsepower sticker on that powerful motor will still be shiny.  But the grind-chamber will have rusted away, and you'll need to keep your plumber's phone number on speed-dial!

What's the solution?

Don't waste your money on a disposal with a powerful motor, if any of the parts that get wet are made of galvanized steel!    Make sure that whatever you buy has only stainless steel components in the grind chamber.  Then, if you have money to burn and it makes you happy, go ahead and spring for that manly motor option.

It bears repeating: Galvanized steel parts on the inside of  a disposal are not acceptable.  Their use is unconscionable, and frankly borders on fraud. 

What's so bad about galvanized steel?

Galvanized steel isn't bad --- provided it's used in an appropriate environment.   The steel is coated with a very thin protective zinc-coating, which can do a great job of preventing rust,  provided that zinc shell remains completely intact.  But one little nick, and the "corrosion-clock" starts ticking.  Eventually, electrolytic action will turn every last bit of the underlying steel to rust.

So galvanized steel isn't bad, unless it's used in a harsh wet environment.  Like, say, on the inside a garbage disposal?

How do I know if galvanized steel is used in my disposal?
Unfortunately, sometimes it's hard to be sure.   You may have to decode "marketing-speak" terms, such as:
Corrosion-Resistant ==> Galvanized Steel
Corrosion-Proof     ==> Stainless Steel

One thing you can be sure about, is disposal manufacturers love galvanized steel components!   They are cheap to make, and most people don't even know they should care.    Better yet, they ensure that people will keep buying new disposals, every few years like clockwork.   

Manufacturers have a good idea of exactly how long their galvanized steel components will last, and set their warranty period accordingly.   If your disposal has a two-year warranty, you can be sure all the galvanized parts on the inside will have dissolved after about two years.   


Even if your garbage-disposal seems to be working OK, I suggest you get a flashlight and peek inside -- after you run it, of course, to get rid of the really gross stuff.   If all you see is shiny metal, then no worries!   

But if you see rusted metal,  and holes where there should be metal, start shopping for a new disposal with stainless steel grind components.   Humongous horsepower is optional. 


  1. Thank you for this! I found you with a google search and I'm glad I did. You helped me understand why my disposal is having issues and helped to steer me away from the cheaper galvanized steel disposals.

  2. You might be the ONLY person to ever read this. So I'm glad you found it too! And you made my day, because If this article helps just one person (that'd be you), then writing this was worth the ridiculous time it took me to write it. :-)

    And now, you and I are the only two people in the world who know that galvanized steel is the devil's metal, when used in inappropriate places, like INSIDE a disposal!

    1. Hi - don’t know if you’ll see this (5-6 years since first article?), but I found your info very helpful, as well! My disposal looks like that when I can see it - it stopped working and sometimes water gets backed up (like right now). Trying to figure out where it’s clogged to help with drainage. I know I probably need a new one, but I’m just curious as to what happened with this one. Thanks!

  3. Now there are three of us. :)



    1. Well then, we've got the disposal manufacturers losing sleep tonight! ;-)

      Thanks, Paul.

  4. Greg BeckmeyerAugust 06, 2016

    Make that 4.
    Have to replace yet another Badger 5. After looking, wanted to go with Waste King L-8000, but between having to order online and changing electrical connection I just don't have the time right now. Hopefully $40 more for Badger 15SS will be well spent.

  5. Count me in as well. My garbage disposal is running but it's all rusted inside and it has a big hole and no shredder ring. Looks like it's time to buy a new one.
    Do you have any experience with Dish Washers too :) I would love to hear more from you.

  6. Hello Mr. Wizard,

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