Peer inside the middle of your sink and into the exit pipe, and you’ll see a place that is both mysterious and scary: the garbage disposal. Aside from plumbers and garbage-disposal-salespeople, few of us have any idea what happens in those moments that we dump food down the sink, turn on the switch, and watch it vanish.

Turns out a lot of us have some incorrect ideas about that unit and how to operate it. Here are some of the most common.

Myth #1: You Should Run Hot Water When the Disposal is On

It’s a solid practice to turn on the faucet when you use the garbage disposal. The running water helps flush food down the pipe, keeping it from getting lodged and causing a clog.

However, somewhere along the way, a rumor began that hot water is more beneficial than cold for this practice. The reverse is actually true. While cold water helps flush debris, hot water can cause fats and oils to stay in a liquid state, only cooling once they reach lower down in the pipes and hardening to form an obstruction.

Ideally, no fat or oils should ever go down your drain, but if they do, warm water only makes it worse.

Myth #2: Garbage Disposals Hurt the Environment

In years past, wastewater treatment plants didn’t have nearly the technology we do today, which meant that in some cases, what you threw down your drain could actually end up in the public water supply. Today, water facilities have no problem processing out anything harmful that is put into the drain, posing little risk to the community.

In fact, many experts would rather you actually put it down the drain rather than in the trash. Food waste that sits in landfills can generate huge amounts of methane gas that pollute the air. If the food waste is in water, however, it’s much easier to eliminate.

Myth #3: Disposals are Filled With Whirring Blades

Contrary to popular perception, garbage disposals are not the equivalent of Edward Scissorhands in your sink. Adding even more to this myth, many homeowners believe that you can (and should) sharpen the blades in your garbage disposal periodically to make the process more efficient.

Wrong and wrong. The inside of most garbage disposals more closely resembles a grinder, with small teeth rotating at very high speeds to destroy waste, much like a cheese grater on steroids. No need to throw ice or egg shells down the sink either to sharpen the “blades” either; these could actually end up hurting the system rather than making it better.

Myth #4: Garbage Disposals Can Destroy Anything

We all know people that throw just about everything in their sink: chicken bones, coffee grounds, etc. Most likely, the people that do so are also wondering why they need to replace their disposals every few years, thinking that anything they put down the drain is gone.

We’ve covered some of the things you should never put down your sink in another article, but suffice it to say that anything solid, anything stringy that can cause a jam, and anything that is oil and fat-based (like bacon grease) should be avoided at all costs. Your garbage disposal is an impressive machine, but even it has its limits as to what it can do

Myth #5: Lemons Make the Disposal Smell Better

You would be surprised to know how many people believe that lemons will help clean your disposal and make it smell better. While it’s partially true – it can alleviate stale food odors, for instance – the fact remains that lemons are so acidic that regularly disposing of them through the drain can actually damage the parts in your disposal.

What should you do? Let your device clean itself. Modern garbage disposals are equipped to destroy many items into easily-flushable debris, so there’s no reason to worry about the device itself becoming odorous (at least, for long periods of time). Skip the lemon treatment, and use them in your iced tea instead.