I live in the middle of the US, our tap water comes from the local river, and our sewer goes back to the local river. Communities up and down the river get their water and return their waste to the same river.

A considerable amount of energy goes into treating the water and the sewer.

I found the related post How 'clean' should something be for recycling? there are several varied answers about how clean recycling needs to be and many variations of how clean people get recylables, and for what reasons.

I assume that steel cans, plastic container, aluminum cans, etc all have different energy requirements where recycling is the most sustainable choice. It would also seem realistic that cleaning of some objects prior to recycling is less sustainable then recycling them without cleaning.

How can I know when cleaning (and recycling) a recyclable is less sustainable than throwing it away?

  • @Erik a chilli can or a bottle of liquid soap. But I don't know what is excessive cleaning, that is the point of the question. I imagine that if it takes more water then the container holds to clean it, you are wasting more resources then you are saving. Aug 2, 2019 at 11:00
  • Follow-up: Why are you under the impression, that this stuff needs thorough cleaning? Has someone told you so?
    – Erik
    Aug 2, 2019 at 12:48
  • Further thoughts: When using liquid soap, I usually add a bit water, when the bottle is almost empty, to maximise its "yield". Similarly, when using canned food, I usually add a bit water (4 to 5 spoons), slosh it around in the can and add the now flavoured water to my dish/cooking. Though, if we really wanted to be sustainable, we used paper-wraped soap or wouldn't buy canned food ;-)
    – Erik
    Aug 2, 2019 at 13:15
  • 'Excessive' is irrelevant to the question, you just want to know when cleaning takes too much resources.
    – user2451
    Aug 7, 2019 at 13:52

1 Answer 1


Here we have a more expensive disposal system for anything with food residue. Dry goods and wet goods go to different land fills. They encourage us to rinse food containers and discard into the dry waste/construction waste.

In the recycle streams they don't take dirty paper/cardboard or dirty sheet plastic. But they take any kind of plastic pail, even ones that had motor oil in them. Oil is drained out, the plastic chipped, rinsed with solvent, and the chips recycled into things like nursery pots.

Two rubrics occur from these examples:

  • Rigid materials are easier to clean. So chipping and cleaning isn't unreasonable.
  • Stuff with high surface to mass ratios (foams, thin sheet goods) are more likely to be unaffordable to clean.
  • Stuff that is going to be processed with high heat and a runny liquid state can be sorted/filtered in that state.

Paper is dissolved, and sand/dirt difficult to separate.

Steel, aluminum will be smelted, and organics burned off, and dirt trapped in the slag.

Plastic is heated to the gooey stage, then is molded/ turned into garbage bags, etc. Hard to separate dirt.

There are some applications that would make a new market for some types of waste:

E.g. Styrofoam right now is difficult to deal with. Even crushed, the low density makes transport expensive. A possible use could be to wash it, drain it, then mix with an acetone/water/alcohol solution that partially dissolved the surface, then press it into large lego blocks. Sand would actually be a useful addition givening them enough mass to not blow around. A system using these would make for inexpensive emergency shelter. Mould grooves into the exterior surface, and you can plaster them for longer term use. (Styrofoam degrades in sunlight. Mould grooves into the top surface and you have easy to run wiring channels (As long as you wire when erecting walls.

E.g. A while ago you could buy fence posts made from wood chips and plastic bags. Dirt didn't matter, nor the type of plastic. Melt together and extrude under pressure. The material was dense, not very strong, heavy, and incredibly ugly. Never caught on.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.