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Anything single-use is suspicious in terms of sustainability, especially if it goes to the trash afterwards and is not recyclable. Considering that, and the disproportionate use of paper towels by the United States, it makes me wonder if a more sustainable but also safe/hygienic alternative to paper towels is single-use-then-wash rags.

In some cases rags can be used multiple times before needing to be washed (e.g. wiping up water spills separate from cooking surfaces). With the nastiest messes (e.g. vomit or a pet going to the bathroom indoors) rags from a designated "dirtiest rags" pile could be used and washed immediately after. Rags for various uses can be sourced from recycled material such as ripped clothing.

Even using a washing machine and hot water to wash these rags, intuitively I'd think the rag approach is still using way less energy and has a lesser environmental impact than using paper towels. Is there anymore supporting evidence to confirm or deny that?


Some key assumptions:

  • Domestic washing machine and hot water is already in use in most American homes so switching from paper towels to rags would only increase use of those things, not require the fixed cost/impact of initially getting large appliances.

  • Some of the nastiest messes require more energy for more thorough washing and use of hot water. To some extent this balances out as plenty of rags can be washed at once whereas these nastier messes can require many single-use paper towels to clean up.

  • Aside from the absorbant material being used - recycled & reusable rag or single-use paper towel - cleaning methods would be basically constant.

  • Paper towels are packaged in throw-away plastic (even when bought in bulk) and even if they're sourced from post-consumer recycled material or sustainable forestry, there is still industrial processing to begin with and large-scale waste management to end with (incineration in our case, landfills in most other places).


I see similar questions in Reusable vs. disposable diapers: which is better? and especially Tissues or cloth to clean a baby - what's more sustainable? which both seem to support rags being better than single-use/disposable items like tissues or diapers. Does the same apply to paper towels?

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Your assumption seems to be correct -- consuming paper towels demands about eight times more energy than machine-washing and hang-drying reusable rags made from discarded textiles.


In order to provide an answer that fits within the character limit, I'm going to focus on energy as the measure with which to compare paper towels against machine-washed rags. Otherwise, analysis could be skewed by counting renewable energy for one product against fossil fuel energy for the other. I will also try to account for land use, which should always be a consideration with forest products.

I'm also going to assume that one rag has cleaning power equivalent to two sheets of 2-ply paper towel (about 8 grams worth).

Paper Towel

We have access to a detailed life cycle inventory (LCI) of paper towel courtesy of the US EPA and P&G. This LCI uses a paper towel roll (191 grams) as the functional unit. I will calculate a single use as 4% of the roll, based on my guess stated above for equivalent cleaning power.

Producing a roll of paper towel uses several kinds of fuel and energy at various stages. We can make these comparable by multiplying the energy content, or calorific value of each fuel.

  • 1.94 MJ from crude oil (0.0465 kg * 41.8 MJ/kg)
  • 5.22 MJ from natural gas (0.100 kg * 52.2 MJ/kg)
  • 0.38 MJ renewable energy
  • 5.22 MJ from coal (0.173 kg * 30.2 MJ/kg)

Very roughly speaking, it takes 12.76 MJ of energy to produce a roll of paper towel, or 0.51 MJ for two sheets to clean up a single mess.

Machine Wash

I was also able to locate a life cycle analysis of clothes washing machines (link to PDF).

I'm going to assume that a rag weighs about 25 grams, based on how many rags I've been able to produce out of my worn t-shirts.

Most of the energy use for machine washing is in the drying phase, so I'll provide both numbers here. These numbers are for 1 kg of dry clothing.

  • 2.476 MJ (wash-only)
  • 12.196 MJ (wash & dry)

So roughly speaking, it takes 0.06 MJ to wash a single rag, or 0.30 MJ to wash & dry a single rag.

Discussion

It does appear that producing paper towels demands more energy than just washing reusable rags, just like you guessed in your question.

Also, it was clear to my when I read the paper towel LCI that the impact of plastic wrapping is almost negligible in every category of sustainability.

The contribution of packaging to the results is low (<1%) it is not included in the tables and graphs of the analysis.

A more thorough comparison might want to consider other aspects of sustainability, such as water use, water contamination, fossil fuel depletion, greenhouse gas emissions, and waste accumulation. However, it would be difficult to compare these aspects without making many more assumptions to set up specific scenarios.

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    Interesting. One question: when you consider washing, how hot is that - heat dominates the energy consumption of a wash load, and not many rags would need to be hot washed, though it may be desirable to wash all rags together. I actually wash floor cloths when I run a cleaning/descaling powder through my machine, as the process seems to work better with something in there. Pick a dry day so you can dry outside and the energy cost is almost zero as the machine needs descaling anyway. But they're not filthy – Chris H Feb 26 at 17:12
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    The base case machine wash scenario I'm citing here is a cold water wash. Switching to hot water would use much more energy, but still less than paper towel. – Nic Feb 26 at 17:23
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    Good answer, but can you say what assumptions about the supply of hot water for the washing machine and the energy rating of the washing machine are used? The report cited appears to list a range of options. I've read that paper towels made with recycled paper have half the carbon footprint, which would make them better than the wash+dry option. I think you need to give the hot-wash figures. Kitchen surfaces need to be hygienic, and cold washed rags are not going to be good enough. – M Juckes Feb 26 at 22:16

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