Plastic Etiquette in Dishwasher


Dishwashers bring convenience to a household, if used wisely. In the last decades, greater knowledge has been gained about chemicals in plastic, and the toxic affects of leaching out due to high water temperatures when washing in a dishwasher.

Manufacturers of food containers have made efforts to remove BPA from plastics, the chemical of concern. New 

Dishwasher safe guidance

Before we start, here is a brief background around the notion of "dishwasher safe." All manufacturers offer guidance regarding the correct washing of their dish product. They will basically indicate one of three directives:

  • do not put in dishwasher
  • dishwasher safe
  • dishwasher safe, top rack only

For convenience,  the directive or a symbol is imprinted (or molded, in the case of plastic) into the bottom of the dish. If you don't see it, read the papers that come with the product.

What dishwasher symbols mean

According to the Finish Dish Washing Detergent company, there are no "official" dishwasher symbols. The most common symbols indicate "top rack safe" and "dishwasher" safe. It really is up to the manufacturer of each dishware to say if their product is safe to be washed in a dishwasher.

I have some plastic cups I bought for the purpose of using on my outside patio. It's marked "dishwasher safe, top rack only." The reason for this is that the heating element on the bottom of the dishwasher can get too hot during the wash or dry cycle for some plastics. The heat can result in damage, discoloration, and even warping to the dish. 

My warped plastic accident was the sleeve of a food chopper from Pampered Chef. The company replaced the sleeve, but I learned my lesson. After that, I was too fearful to put it in the dishwasher again.

Different types of dishwasher safe symbols and warnings.

Different types of dishwasher safe symbols and warnings.

Other dishware symbols

Do not confuse the dishwasher safe symbol with the glass and fork symbol The glass and fork symbol means that the container is safe for food use.

You can put just about anything through a dishwasher, but to error on the conservative side, almost all plastic should go on top. I rummaged through different plastic containers I had. As you can see, they pretty much all recommend dishwasher top rack only.

There is no universal symbol of dishwasher safe. Often, a symbol is combined with words to be very clear to the user how to handle the product.

Which plastics are dishwasher safe?

We have just learned from the section above that it is up to the manufacturer of a product to tell us if their dish, bottle, or plastic container is dishwasher safe. Not all plastics are dishwasher safe. 

There is no physical way to tell if plastic is dishwasher safe. The only way to decide how to wash the plastic is if a "dishwasher safe" wording or symbol is molded into the plastic for the consumer to read.

Anything plastic marked "reusable" is comprised of a stronger and more durable plastic. It should still be put on the top rack and washed on a normal cycle. Stay away from the longer and hotter cycles of sanitizing settings that will leach out the chemicals in plastic.

Our world is full of plastic, and the kitchen is no different. Bottles, plates, eating and kitchen utensils, plates, and plastic cutting boards are all things we need to give extra attention to.

Plastic can go in the dishwasher if the manufacturer of the product indicates that it is dishwasher safe and BPA free. In the absence of clear instructions, the plastic should not be put in the dishwasher.

To know if plastic is dishwasher safe, refer to the above section on dishwasher safe guidelines.

Health concerns of washing plastic in dishwasher

There is more to be concerned about than plastic melting in a dishwasher. It's the leaching of harmful chemicals out of the plastic, such as BPA or BPA alternatives.

This dangerous plastic types is the kind found in disposable plastic. 

Finish Dishwashing Detergent advises that best practice is to only use "BPA-free" products, and indication that the item does not contain the chemical ingredient bisphenol A. Additional caution is given that some companies are still using compounds similar to BPA, so consumer beware.

Do not put number 7 or polycarbonate plastic in the dishwasher. These types contains BPA and has a high potential of leaching out the BPA chemical. "Number 7" is an indication of the recycling code indicating the plastic contains polycarbonate.

Disposable plastic in dishwasher

If you walk down any paper goods aisle in a convenience store, plastic plate, eating and serving utensils, and plastic straws are for sale. They offer a cheap and inexpensive way to be prepared for a picnic or event, where the plastic is intended to be one-use and throw away.

Cheap, plastic takeout trays cannot go in the dishwasher.

Cheap, plastic takeout trays cannot go in the dishwasher.

Plastic cannot go in the dishwasher that is not marked "dishwasher safe." This includes:

  • plastic straws
  • plastic cups
  • plastic unmarked water bottles
  • plastic forks, knives, spoons
  • plastic plates and trays
  • plastic trays with covers for meal prep
  • plastic containers from food bought from grocery store
  • take out, takeaway, or carry out plastic containers from any restaurant
  • styrofoam cups, plates, trays
  • any plastic container not marked

Most of this plastic is seen as "disposable." None of it should go in the dishwasher. Someone pointed out to me the bacteria potential for Styrofoam items. They were concerned that  the Styrofoam had surface texture that would trap bacteria. The thought of re-washing Styrofoam was... gross.

It's common for people to want to know if they can wash and reuse takeout containers.

Plastic takeout containers (non-styrofoam) are safe to wash and reuse, but not safe to wash in the dishwasher or reheat in the microwave. Takeout containers should be marked "food safe" if reusing for food use.

Again, avoid the dishwasher if the plastic is not identified as dishwasher safe. The heat will make chemicals contained in the plastic to leach out.

plastic food containers from grocery store

Plastic food containers from grocery store containing food cannot go in dishwasher.

Cheap plastic that is dishwasher safe

There is a little heavier plastic that consumers buy when they like to give food away, or not worry about getting the plastic pan, plate or platter back. For example, Rubbermaid's TakeAlongs are stamped as top rack dishwasher safe. I pulled out an old plastic Mainstays plate from Walmart. There is a sticker on the back that says "dishwasher safe - avoid heating element" (that would be the bottom rack).

If that sticker wasn't there, I would have nothing to go by. The plate is made in China. Another tray of similar plastic had no markings on. I've never put that in the dishwasher because it's bigger.

Takeout, takeaway, or carry out plastic containers are not dishwasher safe. They are made from a cheap plastic and can be harmful.

Styrofoam products (plates, cups, takeout trays) should never be washed and reused.

According to the Webstaurant Store, "Melamine tableware is considered 100% dishwasher safe. Most variations of melamine servingware can handle temperatures that exceed recommended dishwasher temperatures. Additionally, melamine has the ability to retain high heat, allowing it to dry faster than standard dishware."

Melamine plastics in dishwasher

According to the Webstaurant Store, melamine is made of a chemical compound that is organic-based and nitrogen-rich. The FDA has deemed BPA-free melamine safe to eat from as long as it isn't heated to a extremely temperatures (e.g.,160 ° F or higher).(e.g.,160 ° F or higher). Webstaurant Store lists dishwasher safe as one of the many benefits of using Melamine products.

Plastic bottles in dishwashers

Of special interest are washing plastic bottles in the dishwasher. Our world has certainly become one of convenience, with more plastic-bottled beverages available. There are different categories to address - not all bottles are made of the same plastic.

There is no way to know if a plastic bottle is dishwasher safe unless it is indicated with a mark, symbol, or warning on the bottom or side of the bottle.

Baby bottles

Which baby bottles are dishwasher safe?

According to the Poison.org website, between 2009-2012, most baby bottles made in the U.S. have NOT contained BPA. Baby bottles and sippy cups manufactured in the U.S. since 2012 are BPA-free by law. They are dishwasher safe on a normal setting. Please refer to safety concerns of using dishwashers for sanitizing baby bottles.

Dr. Brown's baby bottles are top rack dishwasher safe. Please refer to the Dr. Brown's website for cleaning instructions.

types of recyclable drinking bottles

Not all drinking bottles can be washed in a dishwasher.

Plastic pre-bottled beverages

Beverage plastic bottles, such as packaged with Gatorade, Powerade, and water are not intended to wash in the dishwasher. They are considered food safe, but not dishwasher safe. They can safely be hand-washed in a kitchen sink. 

Plastic sports bottles and drink bottles

Plastic sports and drink bottles may or may not be dishwasher safe. The majority of reusable water bottles are labeled "BPA-free".  Plastics marked with recycle codes 1, 2, 4, 5, and 6 are unlikely to contain BPA, according to FDA.

Check your water bottle bottom to look for symbols are statements that the sports bottle or water bottle is dishwasher safe. 

Tupperware drink bottles

Certain Tupperware drink bottles are approved to go in the dishwasher. The Tupperware website gives specific care instructions for almost all of their products online.

Tupperware Eco bottles are dishwasher safe, however Tupperware specifically says not to put carbonated beverages into them.

Tupperware cautions on its site, "Eco bottles are not for use with carbonated beverages or with carbonating devices."

Soda Stream Bottles

Soda Stream bottles are part of a special system that consumers can use to make their own carbonated beverages. 

Soda Stream produces a dishwasher safe bottle line and a hand-wash only bottle line. Refer to the bottle itself to identify correct washing procedure.

All Soda Stream bottles are BPA free, including Fizzi One Touch bottles. Although BPA free, it doesn't mean that they are all dishwasher safe. For more information on Soda Stream bottle care, recycling, and best practices, visit the Soda Stream website.

Washing plastic food storage dishes in the dishwasher

There are some big names in the plastic food container industry. Icons like Tupperware and Rubbermaid are at the forefront of the plastics industry. Maintaining a stellar reputation of food safety is key to their success.

Tupperware

Earl Tupper, a chemist, created the plastic that would later by called Tupperware. Modern day Tupperware has been re-formulated to address concerns of the affects of some chemical in the plastic on human health. According the the Tupperware website, "as of March 2010, items sold by Tupperware US & CA are BPA free."

Modern versions of Tupperware are dishwasher safe and BPA free. Vintage Tupperware (anything made before 1979) is not dishwasher safe.

Plastic food cotainers

Check the bottom of plastic food containers to see if it's safe to wash in the dishwasher.

Most items on their website list care instructions for the plastic on the individual product page, and most are listed as dishwasher safe. It is interesting that the items marked as classic Tupperware vintage lack care instructions.

Old Tupperware

My own old Tupperware bowls are not marked as dishwasher safe, the same goes for some Tupperware pitchers I have (but what silly person would put a pitcher in the top rack of a dishwasher, LOL!).  

It is possible that the bowls are dishwasher safe; modern day companies indicate much more clearly these days if their plastic is BPA free and dishwasher safe. Consumers are looking for it.

I had to help clean out an estate with very old Tupperware pieces. They were all tossed out. Yes, I know that some people seek out the vintage Tupperware, but this ancient stuff had its own funk going on - discolored, smelly, all together questionable.

If you have any doubt about your Tupperware product, examine the product directly, as a Tupperware consultant, or visit the Tupperware website.

Washing kitchen appliance accessories in dishwasher

It's common to have blender pitchers, food processor bowls, etc. manufactured from plastic. Each piece will have to be inspected if it carries information molded into the plastic that it is dishwasher safe.

Keep in mind that these types of plastic often have measurement lines molded in, so a dishwasher warning is expected.

In my kitchen, I examined a Hamilton Beach Blender, a Ninja Blender, and a Cuisinart Food Processor. All of the plastic was clear and similar in nature - nothing carried a dishwasher care instruction.

The newest in the collection was the Cuisinart Food Processor. I cannot definitively say if these types of plastics, especially popular for food blenders like Ninja Blender and Nutribullet are dishwasher safe.


Plastic accessories to kitchen appliances.

Some plastic accessories for kitchen appliances may not be dishwasher safe. Refer to the manufacturer to be sure.

Different plastic formulations can come out over time. Due to recent improvements in consumer messaging, a safe plastic product may have missed the window for being identified as safe.

Why a dishwasher catches on fire

Plastic products are pretty much confined to top rack only in a dishwasher. Placing plastic on bottom rack in proximity to the heating element will and can result in damage to the plastic.

It is possible for dishwashers to malfunction and catch on fire. Dishwashers can malfunction for a variety of reasons, including faulty wiring, leaking of water interfering with electronics, and overloading of a dishwasher which affects how hard the dishwasher has to work.

Always stack your dishwasher carefully, and of course, avoid putting plastic on the bottom rack. It is possible that the force of the water from the jets upset dishes, knocking them into disarray - lightweight plastic is especially susceptible to this. Even worse, the plastic can get lodged into other locations where they shouldn't be, even blocking the dishwasher's arms from rotating.

Melted or burnt plastic in a dishwasher is a malfunction that can affect dishwasher performance and cause a fire. Any time you smell burnt plastic, open up your dishwasher and inspect for the source immediately.

What to do about burnt plastic in dishwasher

The source of the burnt plastic smell may have nothing to do with plastic objects inside of the dishwasher. It could be that components of the dishwasher itself are experiencing direct damage. Always have a fire extinguisher nearby - DO NOT put out an electrical fire with water.

Ideally, you would be present when the dishwasher is in operation. Best practice is to not go to bed or leave the house or apartment when the dishwasher is running. If any malfunction happens, you can be there to prevent worse damage (or even fire) from happening.

Removing melted or burnt plastic from dishwasher.

If the source of the burnt plastic is from a plastic item you placed in the dishwasher, wait for the item to cool down enough before removing from the dishwasher. If the plastic item is only malformed, the plastic dish can be removed. Then the dishwasher can be closed and allowed to resume the cycle.

In all situations, thoroughly inspect the inside of the dishwasher to make sure no dishes are under the bottom rack or interfering with the function of the dishwasher. The filter and screen should also be examined to make sure nothing is trapped or blocking the removal of water from the dishwasher.

Dishwasher repairman inspects broken dishwasher.

Contact a trained electrician or repairman if your dishwasher isn't working.

If the plastic item has melted on to other dishes, the dish rack, or the heating element, the cycle will need to be canceled. All dishes will need to be removed from the dishwasher in order to properly clean the melted plastic.

Because of the characteristic of plastic, it may be possible to peel the plastic away and off of other items the melted plastic has come in contact with.

Removing burnt plastic smell

The smell of burnt plastic can be removed from the dishwasher and other dishes with a vinegar wash in the cycle. Make sure that the source of the smell, is indeed, a melted or burnt plastic dish first.

Please refer to the article Using Other Cleaning Products in a Dishwasher that gives directions on using vinegar to removed dishwasher odors.

If you don't know the source of the burnt plastic smell, have a licensed electrician or appliance maintenance technician examine the dishwasher to verify the source of the smell.

Do not continue using the dishwasher until the dishwasher has been repaired and is approved to be safe to to used.

Health concerns about melted plastic

Melted plastic can pose a  health risk. When plastic melts, chemicals are released into the air. The long term affects of exposure to small amounts of melted plastic is not known. The effects are minor when compared to inhaling smoke from a house fire where large amounts of toxic chemicals are being released into the air from the burning contents.

According to Poison.org,  "if someone had a single exposure, it would be entirely gone from the body after a day. Repeated exposures are necessary to have measurable levels on a regular basis."

Poison.org goes into greater detail about the potential harm of BPA, the main ingredient in plastic. This can provide a better understanding about BPA in the human body.

The most important action to take is to remove the damaged plastic from the home. Remove the melted plastic from the living environment for additional protection from exposure to the melted plastic. If you are able, open a window to bring in fresh air into the space, leave it open as long as it takes to air the room out.

About the author 

Renee Matt

Renee is a former kitchen designer, home remodeling enthusiast (having lived through several DIY projects), and an Iowa farmwife. Renee is passionate about preparedness, garden skills, and knowing where her food comes from. Years of being a stay-at-home mom and supporting the family farm with hearty meals has been key to Renee's pantry readiness. She uses her professional IT background and expertise to bring the Everything Pantry website to life.

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