Show your work

The evidence.

This campaign asks for something laughably small, so the numbers behind it have to be solid. Every statistic on this site traces to a source you can read yourself — most of them primary: government lifecycle assessments, peer-reviewed journals, UN and OECD reports. Where a popular factoid didn't survive checking, we left it out.

Numbered citations link to the full reference list below.

Part one

The scale of
"use once,
toss it."

Single-use isn't a personal failing — it's an industrial system. Here is what it adds up to, with dates attached, because honest numbers have dates.

292.4M tons
of municipal solid waste generated in the US in 2018 — about 4.9 pounds per person, per day. Under a third was recycled or composted.
US EPA, 2018 data 1
28.1%
of that waste — 82.2 million tons — was containers and packaging: the boxes, bags, cups, and wrappers designed to be discarded on arrival.
US EPA, 2018 data 1
~9%
of all plastic waste ever generated (through 2015) has been recycled. About 79% has accumulated in landfills or the environment.
Geyer, Jambeck & Law, 2017 2
460M tonnes
of plastic produced globally in 2019 — roughly double the year 2000. Of 2019's plastic waste, again only 9% was recycled. The plastics lifecycle caused 3.4% of global greenhouse emissions — 90% of that from production, not disposal.
OECD Global Plastics Outlook, 2022 3
1 in 400
UK paper coffee cups actually gets recycled — the plastic lining defeats paper mills. The UK alone goes through about 7 million cups a day, roughly 30 g CO₂e each.
Foteinis, 2020 4
1–5 trillion
plastic bags are estimated to be consumed worldwide each year. (You'll see "5 trillion" quoted alone; the UN's own estimate is this range.)
UN Environment Programme, 2018 5
44%
of litter items catalogued in aquatic environments worldwide are just four things: single-use bags, plastic bottles, food containers, and wrappers. Takeout plastic "largely dominates global litter."
Morales-Caselles et al., 2021 6
"…growth of plastics packaging… was accelerated by a global shift from reusable to single-use containers." — Geyer, Jambeck & Law, Science Advances, 2017 2

Part two — the twist

Your tote bag
has a debt.

Here's the part almost nobody tells you: a reusable product starts life deep in environmental debt, because making it costs far more than making the disposable it replaces. It only pays that debt off through use — often a lot of use.

Lifecycle researchers measure this as a break-even point: how many times must the reusable be used before its total footprint drops below the single-use alternative? The answers are consistently higher than intuition says:

The reusable What it replaces Uses to break even Measured on Source
Paper bag Single-use HDPE grocery bag 3 Climate (GWP) UK EA 2011 7
"Bag for life" (LDPE) Single-use HDPE grocery bag 4 Climate (GWP) UK EA 2011 7
Non-woven polypropylene tote Single-use HDPE grocery bag 11 Climate (GWP) UK EA 2011 7
Cotton tote Single-use HDPE grocery bag 131 — rising to 173 if the plastic bags would have had a second life as bin liners Climate (GWP) UK EA 2011 7
Conventional cotton tote LDPE bag (reused once as a bin bag) 52 on climate alone; 7,100 across all 15 environmental indicators Climate / all indicators Danish EPA 2018 8
Organic cotton tote LDPE bag (reused once as a bin bag) 149 on climate alone; 20,000 across all 15 indicators Climate / all indicators Danish EPA 2018 8
Ceramic mug Paper cup 39 Energy Hocking 1994 9
Ceramic mug Foam (polystyrene) cup 1,006 Energy Hocking 1994 9
Ceramic mug Paper cup with lid 200–300 Full LCA (Québec) CIRAIG 2014 10
Reusable polypropylene cup Single-use cups 5–10 with industrial washing; hand-washing on site never breaks even Climate Cottafava et al. 2021 11
Reusable PP container ("Tupperware") Styrofoam (EPS) takeout container 18+ on carbon; 16–208 across impact categories; never on terrestrial ecotoxicity Carbon / all categories Gallego-Schmid et al. 2019 12
Aluminium water bottle 500 ml single-use PET bottle producing one 1 L aluminium bottle emits as much CO₂e as producing roughly 142 PET bottles (our arithmetic from the study's production figures); a separate Quantis LCA puts typical aluminium-vs-PET break-even at ~10–20 uses, ~50 worst-case Production CO₂e Summa et al. 2026 13 · MIT/Quantis 14
Read the fine print with us. These numbers depend on what you measure. The famous "20,000 uses" figure is organic cotton measured across all 15 indicators in the Danish study — driven almost entirely by ozone depletion; on climate alone the same bag needs 149 uses (conventional cotton: 52)8. Results also shift with geography, electricity grids, and above all washing: in the Québec study most of a travel mug's lifetime impact was hand-washing — "a quick rinse in cold water (without soap) would bring travel mugs almost on par with ceramic mugs"10, and the bottle study found machine dishwashing beats hand washing environmentally and cuts microbial load by about 90%13. Over a year of daily use, a reusable bottle's production impact "becomes negligible independently of the material"13.

So the punchline isn't "reusables are bad." It's this: the greenest object is the one already in your hand. Use the disposable one more time before it goes. And if you own a reusable — a tote, a mug, a bottle — the single best thing you can do for its footprint is use it, hundreds of times, until it falls apart. Abandoning it in a cupboard after ten uses is worse than never having bought it.

As the UK Environment Agency put it: "Whatever type of bag is used, the key to reducing the impacts is to reuse it as many times as possible."7

One more finding worth knowing: the same UK study found that reusing grocery bags as bin liners cut their impact by 13–33%, because each reused bag avoids manufacturing a dedicated liner — and that "reuse as bin liners produces greater benefits than recycling bags."7 The humble bag-in-the-bathroom-bin is, by the evidence, the single best idea on this site.

Part three

What the
books say.

Two books shaped this campaign. Both are worth your library card. All quotes below are verbatim.

Cradle to Cradle (2002)

William McDonough & Michael Braungart 15

The book's core argument: waste is a design flaw, not a law of nature. Products are designed as one-way trips — and most "recycling" is really downcycling, degrading material quality with each pass until it lands in a landfill anyway. Nature doesn't work that way:

"Nature operates according to a system of nutrients and metabolisms in which there is no such thing as waste." — p. 92
"The Earth's major nutrients—carbon, hydrogen, oxygen, nitrogen—are cycled and recycled. Waste equals food." — p. 92

Their answer is to redesign products as "nutrients" — biological ones that safely return to soil, technical ones that cycle back into industry forever. Until things are designed that way, squeezing more use out of what already exists is the improvisation available to the rest of us.

More about the book at mcdonough.com →

Plan B 2.0 (2006)

Lester R. Brown 16

Brown named the system this campaign pushes against — the throwaway economy — and traced how it was built, substitution by substitution:

"Thus we have substituted facial tissues for handkerchiefs, disposable paper towels for hand towels, disposable table napkins for cloth ones, and throwaway beverage containers for refillable ones." — Chapter 6
"The challenge is to replace the throwaway economy with a reduce-reuse-recycle economy." — Chapter 6
"A refillable glass bottle used over and over requires about 10 percent as much energy per use as an aluminum can that is recycled." — Chapter 12

Reuse, in Brown's ledger, beats even recycling — recycling still melts, pulps, and remanufactures; reuse just… uses the thing again.

Read the full text free: "Throwaway Economy in Trouble" (Ch. 6) · "A New Materials Economy" (Ch. 12)

Part four

How the
calculator
works.

The impact calculator on the home page is deliberately simple. Here are its exact constants, where they come from, and what it can't tell you.

You pick an item, set how many you'd reuse per week, and set how many people are doing it with you. We multiply: items × 52 weeks × people, and apply one per-item CO₂e constant:

ItemCO₂e per itemWhere that number comes from
Plastic grocery bag (HDPE) ~19 g UK Environment Agency 2011: a month's shopping = 82.14 bags = 1.578 kg CO₂e (Table 5.1) 7
Paper coffee cup ~30 g Foteinis 2020: UK cup footprint of 75 kt CO₂e/yr over ~2.5 billion cups 4
500 ml PET water bottle ~92.5 g (production only) Summa et al. 2026: production-phase GWP of a single-use 500 ml PET bottle 13
What this doesn't capture. These are rough, order-of-magnitude estimates, not an audit. Real footprints vary with geography, manufacturing, and end-of-life. The bottle figure is production-only (the largest phase, but not the whole lifecycle). And one honest subtlety: reusing an item only avoids manufacturing when it displaces a purchase — a bag reused as a bin liner avoids buying a liner; a cup reused as a pen holder avoids one only if you'd have bought one. The calculator's "items kept in service" count is exact by definition; the CO₂e figure is the upper-bound story if each reuse displaces a new item. We'd rather tell you that than pretend the number is precise.

You won't find a "gallons of water saved" number anywhere on this site. Per-item water figures circulate widely, but we couldn't trace any of them to a verifiable source — so rather than show a number we can't stand behind, we show none.

Part five

References.

Numbered as cited above. Links go to the primary source wherever one is freely readable.

  1. US Environmental Protection Agency. Facts and Figures about Materials, Waste and Recycling (data year 2018). National overview · Containers & packaging
  2. Geyer, R., Jambeck, J.R., & Law, K.L. (2017). "Production, use, and fate of all plastics ever made." Science Advances 3(7): e1700782. Open access
  3. OECD (2022). Global Plastics Outlook: Economic Drivers, Environmental Impacts and Policy Options — Policy Highlights. PDF
  4. Foteinis, S. (2020). "How small daily choices play a huge role in climate change: The disposable paper cup environmental bane." Journal of Cleaner Production 255: 120294. DOI
  5. UN Environment Programme (2018). Single-Use Plastics: A Roadmap for Sustainability. Report page · Full PDF (mirror)
  6. Morales-Caselles, C., et al. (2021). "An inshore–offshore sorting system revealed from global classification of ocean litter." Nature Sustainability 4: 484–493. Article
  7. Edwards, C., & Meyhoff Fry, J. (2011). Life cycle assessment of supermarket carrier bags: a review of the bags available in 2006. Report SC030148, UK Environment Agency. Full PDF
  8. Bisinella, V., Albizzati, P.F., Astrup, T.F., & Damgaard, A. (eds.) (2018). Life Cycle Assessment of grocery carrier bags. Environmental Project no. 1985, Danish Environmental Protection Agency. Full PDF · Our World in Data summary
  9. Hocking, M.B. (1994). "Reusable and disposable cups: An energy-based evaluation." Environmental Management 18(6): 889–899. Springer · tables reproduced by Tufts. Break-evens assume an efficient commercial dishwasher; with an inefficient washer, reusables may never beat foam.
  10. CIRAIG / Polytechnique Montréal, for RECYC-QUÉBEC (2014). Life cycle assessment of reusable and single-use coffee cups. English summary PDF
  11. Cottafava, D., et al. (2021). "Assessment of the environmental break-even point for deposit return systems through an LCA analysis of single-use and reusable cups." Sustainable Production and Consumption 27: 228–241. Open-access manuscript
  12. Gallego-Schmid, A., Mendoza, J.M.F., & Azapagic, A. (2019). "Environmental impacts of takeaway food containers." Journal of Cleaner Production 211: 417–427. Abstract · University press release
  13. Summa, D., et al. (2026). "How sustainable and safe is drinking from refill-and-reuse bottles? An LCA and microbiological assessment." Environmental Research 288: 123212. PubMed. The "≈142 PET bottles" comparison is our arithmetic from the study's production figures (13.10 kg CO₂e for a 1 L aluminium bottle ÷ 0.0925 kg for a 500 ml PET bottle), not the authors'.
  14. MIT Office of Sustainability. "Stuff versus Stuff: Which water bottle?" (summarizing a Quantis LCA: reusable aluminium ≈ disposable PET after ~10–20 uses, ~50 worst-case). Article
  15. McDonough, W., & Braungart, M. (2002). Cradle to Cradle: Remaking the Way We Make Things. New York: North Point Press. mcdonough.com
  16. Brown, L.R. (2006). Plan B 2.0: Rescuing a Planet Under Stress and a Civilization in Trouble. New York: W.W. Norton / Earth Policy Institute. Full text (archived)
Spot a mistake in our numbers? Email chris@justoncemore.org — we'll fix it and credit you. A campaign about honesty has to be correctable.