Dishwasher Safe Symbol on Plastic: The Ultimate Guide

Kitchen, Kitchen Safety
May 2, 2025

When it comes to caring for your kitchenware, knowing which items are safe to go into the dishwasher can save you a lot of frustration. Plastic items, in particular, can be tricky. Some plastics handle the heat and detergent of the dishwasher just fine, while others warp, melt, or even release harmful chemicals when exposed to the intense dishwasher environment.

The dishwasher safe symbol on plastic items is designed to help you avoid those mishaps. Over time, I’ve learned that the dishwasher safe symbol on plastic is one of the most important markers to look for before tossing items into the machine. However, it’s also one of the most misunderstood symbols.

In this blog, I’ll break down everything you need to know about plastic dishwasher safe symbols, how to identify them, and tips for ensuring your plastic items last longer.

Table of Contents

What Does the Dishwasher Safe Symbol on Plastic Look Like?

The dishwasher safe symbol on plastic is usually simple, but it’s important to know what to look for. Typically, the symbol features a square or circle, with plates or containers inside and water droplets or spray lines above them. The water droplets or spray lines symbolize the water and cleaning action that occurs in the dishwasher.

This symbol usually appears on the bottom of plastic containers, mugs, or utensils. It’s a clear indication that the item can be washed in the dishwasher without damage. However, not all plastic items with this symbol are created equal, so it’s important to consider the material and size of the item as well.

For instance, some plastic containers may carry the dishwasher safe symbol but with a specific top rack only indication, which means they’re safe to clean only on the top rack of your dishwasher. This is often to protect delicate lids or thin plastic from warping or melting due to the high heat and pressure in the bottom rack.

Special Markings for Plastic Items

In addition to the basic dishwasher safe symbol, some plastic items will feature additional symbols to indicate specific usage. For example, many plastic items, particularly plastic lids or baby bottles, will be marked with “top rack only” or temperature limits (e.g., 120°C or 250°F). These additional instructions are crucial for ensuring your plastic items aren’t damaged in the dishwasher.

Dishwasher Safe Symbol on Plastic: The Ultimate Guide 2

Types of Plastic and Their Dishwasher Safety

The plastic dishwasher safe symbol can only be trusted if the right type of plastic is being used. Not all plastics can handle the dishwasher’s heat and detergent. For example, polypropylene (PP) and polyethylene (PE) are known to withstand dishwasher temperatures, making them great candidates for the dishwasher. However, polystyrene and polycarbonate can break down or warp under high heat.

When I first started using plastic containers for meal prepping, I didn’t realize the material type was just as important as the dishwasher symbol. I had a few containers marked as dishwasher safe but later found that the plastic lids didn’t hold up as well because of their material, even though they carried the symbol.

Why Some Plastics Are Not Dishwasher Safe

Unfortunately, not all plastics are designed to withstand the intense heat of a dishwasher, and some plastics may warp or degrade over time. Thin plastics or items with non-durable coatings (like painted plastic) should never be placed in the dishwasher, even if the symbol is present.

The key is to understand that while some plastics carry the dishwasher safe symbol, it’s important to consider the material grade. Always check for additional instructions like top rack only or hand wash only symbols if you’re unsure. For instance, if you have plastic baby bottles, they often come with “top rack only” instructions to preserve their shape and safety.

Why Some Plastics Are Not Dishwasher Safe

Not all plastics are created equal, and just because a plastic item has the dishwasher safe symbol doesn’t mean it can withstand high heat or intense detergent exposure. Some plastics simply can’t handle the heat and pressure inside the dishwasher, especially those with thin walls or coatings.

Here are a few common plastics that should never be placed in the dishwasher, even if they have a dishwasher-safe symbol:

Polystyrene (PS): A cheap plastic used in some disposable products. It warps easily and is sensitive to temperature changes.
Polycarbonate (PC): Known for its durability, polycarbonate is often used in baby bottles or clear containers, but it can discolor or crack in high heat.
Acrylic: Common in mugs, frames, or decorative items, acrylic plastic can get cloudy and brittle in the dishwasher.

Even with top rack dishwasher safe symbols, I’ve seen lightweight plastic items lose their shape or begin to melt if not placed correctly. Always double-check the material type and avoid placing items with labels that say hand wash only in the dishwasher, no matter the symbol.

Why Some Plastics Are Dishwasher Safe

On the other hand, some plastics are specifically designed to handle the dishwasher’s heat and detergents. These plastics, such as polypropylene (PP), polyethylene (PE), and certain nylon materials, are more heat-resistant and durable. The dishwasher safe symbol on plastic items made from these materials is usually reliable, and you don’t have to worry about warping or melting when placed in the top or bottom racks.

For example:

Polypropylene (PP): Often found in plastic containers and baby bottles, it can handle higher temperatures and repeated dishwasher cycles.
Polyethylene (PE): Common in food storage bags and containers, this material is dishwasher safe in both top and bottom racks.

These types of dishwasher-safe plastics make life easier, and knowing the difference between heat-resistant plastics and those that can’t handle the heat will save you from frustration.

Tips for Checking Plastic Items and Ensuring Dishwasher Safety

Not all dishwasher safe symbols are created equal, and some manufacturers are more transparent than others. To ensure that your plastic items are truly dishwasher safe, always look for the symbol printed directly on the product, often on the bottom or base. However, just because the symbol for dishwasher safe plastic is present doesn’t always mean the item is suitable for the bottom rack.

Here are a few tips I follow:

Check the symbol for text: Sometimes the symbol will have words like “top rack only” or “dishwasher safe up to 120°C” to give extra information about the item’s durability.
Know your plastics: Materials like polypropylene and nylon are usually safe for the dishwasher, while polystyrene and polycarbonate are more sensitive to heat.
Inspect older items: Over time, some plastics may degrade, even if they once carried the dishwasher symbol. If an item is old or worn, treat it with more care by hand washing.

Best Practices for Washing Plastic in the Dishwasher

Even if an item is marked with the dishwasher safe symbol, it’s important to handle it correctly to avoid damaging it. Here are a few practices I follow to ensure my plastic items stay in good condition:

Always place plastic on the top rack: Top rack only items should never be placed on the bottom rack to avoid the harsh heat and water pressure. The top rack provides a gentler wash, especially for plastics.
Don’t overcrowd the dishwasher: Allow enough space for water to flow freely around your plastic items. This ensures thorough cleaning and prevents the items from getting scratched or warped.
Use the correct dishwasher setting: Some dishwashers have “delicate wash” or “top rack only” settings that can help prevent heat damage to sensitive plastics.

By following these tips, you can preserve the quality and extend the life of your plastic cookware and storage items.

FAQs

How do I know if my plastic items are dishwasher safe?

Check for the dishwasher safe symbol on the item. This symbol, typically located on the bottom, indicates that the item can withstand the heat and detergent in the dishwasher. Look for additional text like “top rack only” for more specific guidance.

Can all plastic items go in the dishwasher?

No, not all plastics are dishwasher safe. Thin plastics, decorative items, or those with painted finishes should be hand washed. Check the dishwasher safe symbol to determine if the plastic can handle heat and water pressure from the dishwasher.

What happens if I put plastic not marked as dishwasher safe in the dishwasher?

Placing non-dishwasher safe plastic in the dishwasher can lead to warping, melting, or discoloration. Over time, these items can lose their shape or integrity, especially in high heat or under heavy water pressure.

What is the top rack dishwasher safe symbol for plastic items?

The top rack dishwasher safe symbol usually indicates that the item should only be placed on the top rack of the dishwasher, where it’s exposed to gentler heat and water spray. This symbol helps prevent plastic warping or melting that could occur on the bottom rack.

Can I safely wash plastic baby bottles in the dishwasher?

Yes, if the baby bottle has a dishwasher safe symbol, it is safe to wash in the dishwasher. However, many baby bottles also carry a “top rack only” symbol to ensure they’re protected from the higher heat in the bottom rack.

Why should I place plastic containers on the top rack of the dishwasher?

Placing plastic containers on the top rack minimizes their exposure to intense heat and water pressure from the bottom rack. This ensures they don’t warp or lose shape, as the top rack provides a gentler wash cycle.

Is the dishwasher safe symbol for plastic always reliable?

While the dishwasher safe symbol is generally trustworthy, old or worn plastics may still degrade even if the symbol is present. Always check for additional warnings or temperature limits if the symbol is unclear, or if the item shows signs of damage.