Dishwasher Safety

I have these relatives who about 10 yrs ago told me not to put plastic in their dishwasher. Their conjecture was that it would partially melt due to the hot water and over time would eventually riun their plumbing. I myself have not practiced this and am living in a home that I know has not followed this precaution and could very well have 25 yrs of plastic residue clinging to our pipes. Do many people believe this? :smack:

Some plastics aren’t “dishwasher safe” or weren’t. I think it has become pretty much the standard now though, and there is a label on the product if it is not dishwasher safe. I don’t know that it would mess up the plumbing, but it can warp the plastic. It’s the same way with microwave safe things now.

I, for one, don’t believe it. Hot water won’t dissolve plastic dishware. A heating-coil drying cycle could soften and deform it, but I have never seen any kind of plastic melt to the point of going down the drain in the temps involved in a dishwasher.

Also, dishwasher detergent contains abrasives which can damage softer materials and coatings. Which is why many nonstick pans are not dishwasher-safe, even though they obviously have no problem with the heat. (Though I don’t know for sure if “dishwasher safe” plastic containers actually stand up to the abrasives…)

Nor I, but I’ve seen a dishwasher turn a plastic bowl into a surreal melty, gooey, drippy looking piece of sculpture.
It’s not common, but there are plastics that’ll get soft at dishwasher temperatures.

The main reason not to put plastic in a dishwasher, from my point of view, is that they do not get at all clean. I don’t know if it’s the hydrophobic nature of the plastic that means the water can’t cling enough to dissolve and wash off the food residue or what, but I can put a dirty plastic bowl in the dishwasher and have it come out looking like it hasn’t been near water, while metal and ceramic items are sparkling.

I started a thread on this a while ago asking why, but nobody seemed to suffer the same problem. Hmm.

I’ve seen warped plastic items, but never seen plumbing problems caused by melted plastic going down the drain. Grease, yes. Hair, yes. Not melted plastic. I think the people were trying to understand why some plastics were labled as “not dishwasher safe”, and came up with their own twist to explain it.