Melted Plastic in Dishwasher? What to Do and Prevent

Why plastic melts in the dishwasher

Plastic melts in a dishwasher when it touches the heating element at the bottom of the tub. The heating element is the metal coil or loop that raises water temperature during the wash and heats the air during the dry cycle. The element itself gets much hotter than the water around it, and most common food containers are made of plastic that softens or deforms well below that surface temperature.

ENERGY STAR certified dishwashers boost water temperatures to 140 degrees Fahrenheit, which improves disinfection compared with hand washing, but the heating element surface can be hotter than the water temperature. A plastic container that falls onto the element, or a lightweight lid that flips over and lands on it, can soften, warp, or melt onto the metal surface.

The melted plastic problem usually happens with items placed on the bottom rack. The heating element sits under the bottom rack, and any plastic that is not securely positioned can drop through the rack tines or lean against the element. Items that are top-rack safe are generally safe because the top rack sits above the element, but an item can still fall through the rack and land on the element if it is not loaded properly.

Melted plastic is not a safety hazard by itself, but it can produce a strong burning smell and can coat the heating element with a layer that reduces its ability to heat water efficiently. A thick layer can also cause the element to overheat in that spot, which may shorten its lifespan.

Which plastics are at risk

Not all plastics behave the same way in a dishwasher. The recycling code on the bottom of a container tells you what type of plastic it is, and that helps you judge whether it belongs in the dishwasher.

Polypropylene (recycling code 5) is the most common plastic used for food storage containers and reusable cups. It has a relatively high melting point for a common plastic and is generally considered dishwasher safe when placed on the top rack. Polyethylene (codes 2 and 4) is also common in food packaging and is generally dishwasher safe on the top rack. Polystyrene (code 6) is used for disposable cups and takeout containers; it deforms at a lower temperature and is not dishwasher safe. PLA (code 7, labeled compostable) is used for some disposable cups and food containers and can warp or melt even on the top rack.

The dishwasher-safe symbol, which looks like a cup and plate with water droplets or steam lines, is printed on the bottom of many plastic containers. The symbol is a better guide than the recycling code, because a manufacturer can design a container with a thicker wall or a more heat-resistant plastic blend. When the symbol is absent, treat the container as not dishwasher safe.

The safest rule is to put plastic only on the top rack, away from the heating element, and to choose containers that are labeled dishwasher safe. If you are not sure, wash the container by hand or put it on the top rack and run a shorter, cooler cycle without heated dry.

How to remove melted plastic from the dishwasher

Safety first: let the dishwasher cool completely before you touch anything. The heating element stays hot for a long time after the cycle ends, and the melted plastic is hot too. Open the door and wait at least an hour, or longer if the dry cycle just finished.

Once the dishwasher is cool, remove the bottom rack so you can see the heating element clearly. Use a plastic scraper or an old credit card to gently scrape off as much of the melted plastic as you can. Do not use a metal scraper or a knife, because you can scratch the coating on the element and damage it.

The plastic that remains after scraping can often be softened and wiped away. Set a hair dryer on its lowest heat setting and point it at the remaining plastic for a minute or two, then scrape again. The plastic softens just enough to peel away without damaging the element.

After you remove the bulk of the plastic, run a short rinse cycle with the dishwasher empty. The hot water will melt or soften any residue that remains, and the water flow will carry it to the filter or down the drain. After the rinse, inspect the element again and repeat the scraping if needed.

If the melted plastic is stuck in the heating element's seams or around the mounting bracket, use a cotton swab dipped in rubbing alcohol to work the softened plastic out of tight spots. The alcohol helps dissolve the residue without scratching the metal.

Do not use a metal scouring pad or abrasive cleaner on the heating element. The element has a protective coating that can be damaged by scratching, which can lead to corrosion and premature failure. If the plastic layer is thick and will not come off, or if the element shows any signs of damage, replace the heating element rather than risk a failing part.

For cleaning the rest of the tub after a melt, see how to clean the dishwasher heating element.

How to prevent melted plastic in the first place

The best way to prevent melted plastic is to keep plastic away from the heating element. That means loading plastic containers, lids, cups, and utensils only on the top rack, never on the bottom rack. The bottom rack sits directly above the heating element, and anything on the bottom rack can slide, tip, or fall onto the element.

Lightweight plastic items are the most likely to fall. A plastic lid or a small cup can be pushed around by the water spray and can flip over the edge of the rack and onto the element. Weigh down lightweight items by placing a heavier item on top of them, or use the tines on the top rack to hold them in place.

Check that the spray arm is not blocked. A plastic item that blocks the spray arm can cause the dishwasher to shift the load, which can send plastic items into the element.

Use a cycle that does not heat as much. Many dishwashers have a light or eco cycle that uses a lower water temperature and a shorter dry time, which reduces the heat exposure. Turn off the heated dry option when you have plastic in the load. The heating element runs during the entire dry cycle, and the air inside the tub can get very hot. Air drying or using the dishwasher's vented dry option keeps the element from running and reduces the peak temperature.

If you buy a new dishwasher, consider one with a hidden heating element. Some models place the heating element under the tub floor, so there is no exposed coil for plastic to fall against.

What to do with the dishwasher after a melt

A single melted plastic event does not mean you need a new dishwasher. After you remove the melted plastic and run a rinse cycle, the dishwasher should work normally. If the heating element is warped or has a visible crack, or if the dishwasher trips the breaker or throws an error code, replace the heating element or call a technician. See dishwasher repair vs replace for guidance.

If the melted plastic residue is inside the wash pump or the spray arm, it can restrict water flow and reduce cleaning performance. Check the spray arm holes for clogs and clean them if needed.

A burning plastic smell that lasts more than one or two cycles after the cleanup can mean that residue is still on the element or somewhere in the tub. Run an empty hot water cycle with a dishwasher cleaner tablet to break down any remaining residue, then check the filter and the spray arms again.

When choosing a new dishwasher to avoid future melts, look for models that have a top-rack-only plastic loading recommendation and a hidden heating element. The ENERGY STAR product finder lets you compare models by energy and water efficiency, and you can check the maker's spec page for the heating element location. See best built-in dishwashers and best 24-inch dishwashers for spec-based recommendations.

What to pick to avoid melted plastic

Questions

Is it safe to run the dishwasher after plastic melts?

Yes, after you remove the melted plastic and run an empty rinse cycle, the dishwasher should work normally. If the heating element is warped, cracked, or if the dishwasher trips the breaker, replace the element before running another cycle.

Can I put plastic containers on the bottom rack if they are dishwasher safe?

Dishwasher-safe plastic that is labeled for the bottom rack can go there, but if you are not sure, use the top rack. The bottom rack sits directly above the heating element, and the heat plus water spray can cause items to slide or tip onto the element.

What temperature melts plastic in a dishwasher?

Most common food container plastics, such as polypropylene and polyethylene, soften and deform above 160 degrees Fahrenheit, and the heating element surface can reach temperatures above the water temperature. ENERGY STAR certified dishwashers boost water to 140 degrees for disinfection, but the element itself is hotter.

How do I remove melted plastic from the heating element without damaging it?

Let the dishwasher cool completely, remove the bottom rack, and scrape gently with a plastic scraper or an old credit card. Use a hair dryer on low heat to soften stubborn spots, then wipe with a cotton swab dipped in rubbing alcohol. Do not use metal tools or abrasive pads.

Will melted plastic ruin the dishwasher permanently?

Usually not. Once you remove the plastic and run a rinse cycle, the dishwasher should perform normally. If the heating element is damaged, you can replace just that part rather than the whole dishwasher.

Should I replace my dishwasher after a plastic melt?

No, unless the heating element is visibly damaged or the dishwasher no longer heats water properly. A single melt is not a reason to replace the appliance. See dishwasher repair vs replace decision for more.