Garbage disposals, or disposers, offer us a great way to manage food waste in the kitchen, but they are subject to several common problems. Draining issues are the most prevalent. There are a few possible reasons why your garbage disposal won’t drain.
Reasons Why Your Garbage Disposal Won’t Drain
The average garbage disposal has no problem grinding most types of food waste. It’s what happens after the grinding that causes the garbage disposal to stop draining.
These clogs happen because the ground food reacts to water (or lack of water) in a certain way. So, when your garbage disposal stops draining, the problem is most likely to be found in the disposal’s waste discharge system, where the drain trap assembly is located.
Over time, the trap and the waste line get coated with food waste. When the coating builds up, it can obstruct the trap and cause the disposal to back up.
So, if your garbage isn’t draining, or it’s draining very slowly, the problem is probably in the drain trap. Downstream of the disposal discharge pipe, you’ll find a U-shaped plumbing fitting—that’s the drain trap. It’s also known as the P-trap.
Some of the most common reasons why clogs occur include:
- Lack of flushing water: A clog is bound to happen if there isn’t enough water in the disposal when it’s grinding. The waste won’t flush through the pipes if there is no water running.
- Grinding up coffee or eggshells: Coffee grounds and eggshells are not big items, but they can cause big problems. When you grind eggshells or coffee grounds, they form a starchy paste that can easily clog your garbage disposal.
- Grinding banana peels: Banana peels are notorious clog makers. They also form a starchy paste that looks like mashed potatoes.
Generally, anything that is similar to mashed potatoes once ground up is not good for your garbage disposal. Banana peels also have stringy fibers that can make things even worse.
- Grinding potato peels: Potato peels are just as bad as banana peels, and they have been causing clogs ever since garbage disposals became a thing. Once ground up, they will quickly clog the drain (check out our Home Remedies for Clogged Drains)as well if you have this problem).
How to Fix a Garbage Disposal That Won’t Drain
If your disposal doesn’t drain when you turn it on, and it just makes a humming sound, there is a clog under the disposal, most likely. Before you try to unclog it, it is very important to shut off the water and the disposal.
Garbage disposals are no toys, so you need to take some precautions to prevent accidents. Once you do this, there are several ways you can try to fix the problem:
Remove the P-Trap
For this step, you’ll need channel-type pliers, a bucket, and a scrub brush or wire. A flashlight could also prove to be very useful.
To avoid making a mess, place the bucket under the drain trap. The trap will probably be full of water and food waste and all of that can easily spill all over the place.
Once the bucket is in place, you can unscrew the slip-nut fitting on the drain trap. If they won’t come off easily, use the pliers. Then, carefully disconnect the pipe and dump the waste into the bucket.
After you dump the water and the food waste, there will probably still be some debris in the trap fitting. Inspect the fitting for obstructions or clogs.
If there is a clog, it’s most likely in the sharp bend of the pipe. It’s best to use a scrub brush to remove the remaining debris. But, if you don’t have one, a straightened coat hanger should also be effective.
Clean the Trap Arm
If you don’t find any debris in the sharp bend of the trap, the clog is most likely in the trap arm. It’s the horizontal portion of the drain that connects the branch drain pipe to the trap.
Loosen the slop nut where the branch drain meets the trap arm and then pull out the trap arm. Use a scrub brush or wire to clean the inside of the trap.
Snake the Branch Drain
It’s possible that the clog is even deeper. If the trap arm and the P-trap are relatively clean, the problem lies in the branch drain that leads to the main drain.
Clogs that are deeper in the plumbing system are more stubborn, so you will need to snake the branch drain with an auger or drain snake in order to clean it. You don’t need anything fancy—a simple 25-ft drum auger should do.
Start by feeding the auger cable into the branch drain. Turn the drum as the auger cable goes past bends. Run the cable back and forth a few times to break up the clog.
Reinstall the Drain
Once you are done cleaning everything, it is time to reassemble the drain. Put the trap arm and the P-trap back in place and make sure to tighten the slip nuts just snug. The trap arm should slope downward toward the branch drain.
Once you’ve made sure everything is in place you can tighten the nuts all the way. Use pliers to tighten them a bit further if necessary. However, you can easily damage the threads or nuts if you over-tighten them, so be careful.
Flush the Drain
To get rid of any remaining loose debris in the drain system, run water down the disposal for a few minutes. If everything looks good, you can do a bigger flush.
Put a stopper over the disposal, run hot water, and wait for the sink to fill up. When it’s full, quickly pull out the stopper. If there is any remaining clog material, this should dislodge it.
How to Prevent Clogs
If you regularly grind greasy or starchy foods, clogs will build up. But you don’t really need to change your dietary habits to prevent clogs.
Once a month, fill the disposer with ice and pour half a Kosher salt cup. Let it all sit for 15 minutes.
If there is any grease or starch in the gap, this will harden it. When you run the water, the salt and the ice will flush all the hardened gunk down the drain.