Can You Put Plastic in the Dishwasher? Temperature Limits by Code

Introduction

Many home cooks ask Can You Put Plastic in the Dishwasher? The answer depends on the type of plastic, the dishwasher cycle, and the manufacturer’s guidelines. Some plastics tolerate the high heat and powerful detergents of a modern dishwasher, while others warp, melt, or leach chemicals. Understanding resin identification codes, temperature limits, and best‑practice loading techniques helps you keep kitchenware safe and extend its useful life.

• Understanding Plastic Types
• Dishwasher Temperature Limits
• Plastic Code Temperature Limits Table
• How to Determine If Your Plastic Is Dishwasher Safe
• Best Practices for Washing Plastic in the Dishwasher
• Common Mistakes to Avoid
• Special Considerations for Specific Items
• Environmental and Health Considerations
• Frequently Asked Questions
• Conclusion

Understanding Plastic Types

Plastics are categorized by a resin identification code (RIC) — a number inside a chasing‑arrows triangle. This code tells you the polymer family, which largely determines heat resistance and chemical stability. Not all codes are created equal when it comes to dishwasher safety.

Resin Identification Codes

The most common codes you’ll encounter on household items are:

• 1 – PET (Polyethylene Terephthalate): Used for single‑use water bottles and some food jars. Generally not dishwasher safe because it softens near 70 °C (158 °F).
• 2 – HDPE (High‑Density Polyethylene): Found in milk jugs, detergent bottles, and sturdy containers. Handles temperatures up to about 80 °C (176 °F) and is often labeled dishwasher safe on the top rack.
• 3 – PVC (Polyvinyl Chloride): Rare in food‑contact items; can release plasticizers at high heat. Avoid dishwasher.
• 4 – LDPE (Low‑Density Polyethylene): Used for squeeze bottles and some bags. Low heat tolerance (≈70 °C). Usually hand‑wash only.
• 5 – PP (Polypropylene): Common for reusable food containers, microwave‑safe bowls, and many dishwasher‑safe items. Withstands up to 100 °C (212 °F) and is the most reliable code for dishwasher use.
• 6 – PS (Polystyrene): Includes rigid foam cups and clear clamshell containers. Becomes brittle and can warp above 70 °C. Not dishwasher safe.
• 7 – Other (including polycarbonate, Tritan, bioplastics): A catch‑all category. Some, like Tritan, are engineered for high heat and are dishwasher safe; others, like polycarbonate, may release BPA at elevated temperatures. Always check the manufacturer’s label.

Common Household Plastics

In everyday kitchens you’ll most often see codes 2, 5, and occasionally 7 on items marketed as dishwasher safe. Code 1 appears on disposable bottles that should never go in the machine. Codes 3, 4, 6 are rarely used for reusable food‑contact products because of their low heat tolerance. When in doubt, look for a “dishwasher safe” symbol (a plate with water droplets) or the manufacturer’s care instructions.

Dishwasher Temperature Limits

Dishwashers run several cycles, each with a distinct temperature profile. Knowing these profiles lets you match the right plastic to the right cycle.

Typical Cycle Temperatures

• Normal / Auto: Main wash 55–65 °C (131–149 °F); final rinse 70–75 °C (158–167 °F).
• Heavy / Pots & Pans: Main wash up to 70 °C (158 °F); final rinse 80–85 °C (176–185 °F).
• Eco / Energy‑Save: Lower main wash 45–55 °C (113–131 °F); final rinse 60–65 °C (140–149 °F).
• Sanitize / Hygiene: Extended final rinse at 70–80 °C (158–176 °F) for a minimum of 10 minutes to meet NSF/ANSI 184.

High‑Heat vs. Eco Cycles

High‑heat cycles (Heavy, Sanitize) provide the best cleaning power but push plastics closer to their deformation thresholds. Eco cycles are gentler, reducing the risk of warping but may leave heavier soils. For borderline plastics (e.g., some code 2 containers), the Eco or a “glass” cycle is the safest choice.

Plastic Code Temperature Limits Table

How to Determine If Your Plastic Is Dishwasher Safe

Follow this step‑by‑step process each time you encounter a new plastic item.

1. Locate the resin code. Turn the item over and find the triangle with a number. Record the code.
2. Check for a dishwasher‑safe symbol. A plate with water droplets or the words “dishwasher safe” overrides the code.
3. Consult the manufacturer’s care guide. Many brands publish PDF manuals online; search the model number plus “care instructions.”
4. Match the code to the temperature table. Use the comparison table above to see the maximum safe temperature for that polymer.
5. Select an appropriate cycle. If the item’s max safe temperature is below the normal final‑rinse temperature (≈75 °C), choose Eco or a low‑heat cycle.
6. Load on the top rack when uncertain. The top rack experiences lower temperatures and less direct spray pressure.
7. Run a test cycle with a single item. After the cycle, inspect for warping, cloudiness, or odor. If any appear, hand‑wash future pieces.
8. Document the result. Keep a small notebook or phone note listing each item’s code, cycle used, and outcome for future reference.

Best Practices for Washing Plastic in the Dishwasher

Adopting consistent habits protects both your plastics and the dishwasher.

• Separate by code. Group code 5 items together; keep code 1, 3, 4, 6 out of the machine.
• Use the top rack for marginal items. Even code 2 containers last longer on the top rack.
• Avoid overcrowding. Adequate water circulation reduces the need for higher temperatures.
• Choose a mild detergent. Harsh alkaline formulas accelerate plastic degradation.
• Skip the heated dry option. Residual heat can push plastics past their limit; air‑dry or “energy‑save” dry is safer.
• Pre‑rinse heavily soiled items. Less soil means the dishwasher can finish on a lower‑heat cycle.
• Inspect after each load. Early detection of warping prevents leaks and food‑safety issues.

Common Mistakes to Avoid

• Assuming all “microwave safe” plastics are dishwasher safe. Microwave safety only addresses short‑term heat; dishwasher cycles are longer and hotter.
• Placing thin, single‑use bottles (code 1) on the bottom rack. Direct spray and higher temps cause immediate deformation.
• Using the sanitize cycle for every load. Unnecessary high heat shortens the lifespan of even code 5 items.
• Ignoring manufacturer labels. A “hand wash only” label supersedes any generic code guidance.
• Stacking heavy pots on top of plastic containers. Mechanical pressure combined with heat leads to cracking.
• Reusing warped containers for food storage. Deformed plastics can harbor bacteria and may leach chemicals.

Special Considerations for Specific Items

Baby Bottles

Most modern baby bottles are made from polypropylene (code 5) or Tritan (code 7). They are generally dishwasher safe on the top rack. However, nipples and silicone valves should be placed in a closed basket or on the top rack away from direct spray to prevent tearing. Avoid the sanitize cycle unless the manufacturer explicitly approves it, as prolonged high heat can degrade silicone.

Food Storage Containers

Containers labeled “microwave and dishwasher safe” are usually code 5. Lids often have a different polymer (sometimes code 1 or 2) and may warp faster. Wash lids separately on the top rack, and replace any lid that no longer seals tightly.

Reusable Water Bottles

Stainless‑steel bottles with plastic caps: the metal body is dishwasher safe, but the cap (often code 5 or 7) should go on the top rack. Bottles made entirely of Tritan (code 7) can handle the normal cycle, but check for a “dishwasher safe” stamp. Avoid bottles with insulated double walls that trap water; they can develop mold if not dried thoroughly.

Environmental and Health Considerations

Repeated high‑heat exposure can cause some plastics to release additives such as plasticizers, antioxidants, or residual monomers. While regulatory agencies set migration limits, minimizing unnecessary heat reduces cumulative exposure. Choosing durable, dishwasher‑safe polymers (primarily code 5 PP and certified code 7 Tritan) cuts waste by extending product life and lowering the frequency of replacement. When a plastic shows signs of degradation — cloudiness, cracking, or off‑odors — retire it from food service and recycle according to local guidelines.

Frequently Asked Questions

Can You Put Plastic in the Dishwasher?

Yes, but only plastics rated for the temperatures your dishwasher reaches. Polypropylene (code 5) and certain code 7 materials like Tritan are generally safe on all racks. Always verify with the manufacturer’s label or care guide.

What Happens If You Wash Non‑Dishwasher‑Safe Plastic?

The item may warp, melt, become brittle, or release chemicals into the wash water. Warped containers can leak, and degraded plastics may contaminate dishes.

Is the Top Rack Always Cooler?

In most residential dishwashers the top rack experiences lower spray pressure and slightly lower temperatures (often 5–10 °C cooler) than the bottom rack, making it the safer zone for marginal plastics.

Can I Use the Sanitize Cycle for Plastic?

Only if the plastic’s maximum safe temperature exceeds the sanitize rinse temperature (typically 70–80 °C). Code 5 PP usually tolerates it, but many code 2 and code 7 items do not. Check the label first.

How Do I Know If a Plastic Container Is BPA‑Free?

Look for “BPA‑free” labeling or choose containers made from polypropylene (code 5) or Tritan (code 7), which are manufactured without bisphenol A. Polycarbonate (also code 7) may contain BPA unless explicitly stated otherwise.

Should I Hand‑Wash Plastic Lids?

If the lid is a different resin code than the base (common with code 1 or 2 lids on code 5 containers), hand‑washing extends its life and maintains a proper seal.

Conclusion

Determining whether you can put plastic in the dishwasher comes down to three factors: the resin identification code, the dishwasher cycle’s temperature profile, and the manufacturer’s explicit guidance. Polypropylene (code 5) and certified Tritan (code 7) are the most reliable choices for repeated machine washing, while codes 1, 3, 4, 6 should stay out of the dishwasher entirely. By reading the code, selecting an appropriate cycle — preferably Eco or top‑rack only for borderline items — and following best‑practice loading habits, you protect both your health and the longevity of your kitchenware. Remember to inspect items after each wash, retire any that show damage, and recycle responsibly. With these steps, the question Can You Put Plastic in the Dishwasher? becomes a confident “yes” for the right plastics and a clear “no” for the rest.