Pollution
Animals have to eat, drink, pee, and poo. Imagine the waste of 90 billion farm animals
78%of river and ocean waste pollution comes from farms
We raise and kill about 88 billion land animals a year; they create a huge amount of solid and liquid waste. In the U.S. alone, their manure is about 13 times the solid waste from the entire human population. That waste runs off into rivers and oceans, causing dead zones where no life can survive. Farms cause about 78% of the nutrient pollution that creates those dead zones. We wouldn't have so much waste and dead zones if we chose to not harm or eat animals.
What the evidence says
The main points first. Every claim is tied to a source below.
Our World in Data · Environmental impacts of food production
Animals have to eat, drink, pee, and poo. Imagine the waste of 90 billion farm animals
Farm animals eat, drink, poop, and pee. That is not a small extra. About 80% of agricultural land is used for grazing and feed. About 70% of the world’s freshwater withdrawals go to agriculture, most of it to those animals. We raise and kill about 88 billion land animals a year; they create a large amount of solid and liquid waste. In the U.S., EPA figures put their manure at about 13 times the solid waste from the human population. That waste does not stay in the barn. It runs off into rivers and oceans, causing dead zones where no life can survive. We do not have to harm or eat animals at all.
About 78% of river and ocean waste pollution comes from farms
Poore and Nemecek found that farms cause about 78% of the nutrient pollution that suffocates rivers and oceans. Food production is also about a third of the acid that rains onto land. Most of that is not a plate of beans. It is feed, pee, and poop.
Our World in Data · water pollution per 1,000 kcal · Poore & Nemecek (2018)
Per calorie, meat and dairy pollute water far more than plants
Charts that put plants next to animal foods show beef, cheese, and farmed fish at the top for water pollution per calorie. Peas, nuts, and potatoes sit near the bottom. The extra pollution is the extra animal — the feed they ate and the waste they left.
70% of the world’s freshwater already goes to farms
Same picture as the Water page: 70% of the freshwater we pull from rivers and underground is used for agriculture. Most of that is not salad. It is feed and troughs. When that water leaves the field, the waste goes with it.
UK vegans: about 75% less water pollution than high-meat diets
Among about 55,000 people in the UK, vegan diets produced about 75% less water pollution than high-meat diets — and less climate-heating gas and land use too. Same study as the Carbon page. The waste was never required.
Sources
Papers and datasets. Caveats stay on the card — small samples and single animals included on purpose.
Science, 2018 · Meta-analysis
Poore & Nemecek — eutrophication and acidification
Food production creates about 32% of global terrestrial acidification and about 78% of eutrophication. The farm stage dominates. Lowest-impact animal products still typically exceed vegetable substitutes.
Our World in Data · Review
Our World in Data — food’s environmental impacts
78% of global ocean and freshwater eutrophication is caused by agriculture. 70% of freshwater withdrawals go to farms. Same sheet as the biomass figures.
Our World in Data · Meta-analysis
Eutrophying emissions per 1,000 kilocalories
Poore & Nemecek via OWID: beef, cheese, and farmed fish sit at the top of water-pollution intensity per calorie. Plant foods sit far below.
Nature Food, 2023 · Observational
Scarborough et al. — 75% less water pollution on vegan diets
Among ~55,000 UK eaters, vegan diets produced about 75% less water pollution than high-meat diets, along with less greenhouse gas and land use.
Environmental Health Perspectives, 2007 · Review
U.S. farm animals produce about 13 times human sanitary waste
Burkholder et al., citing EPA: animal agriculture in the United States produces about 133 million tons of manure a year on a dry-weight basis — about 13 times the solid waste from human sewage.
Ecosystems, 2012 · Meta-analysis
Mekonnen & Hoekstra — grey water from farm animals
Grey-water (pollution) footprints of meat and dairy dwarf those of pulses and grains. The nitrogen and phosphorus leave the feedlot and the field.