Pollution
Animals have to eat, drink, pee, and poo. Imagine the waste from 88 billion farm animals
78%of the nutrient pollution in rivers and oceans comes from food production
We breed and kill about 88 billion land animals a year[7], and in the U.S. alone, farm animals produce about 13 times as much waste as the entire human population[5]. That waste runs off into rivers and oceans, and food production causes about 78% of the nutrient pollution that creates dead zones where nothing can survive[1][2]. Vegan diets cause about 73% less water pollution than high-meat diets[4]. If you cared about clean water, you would stop eating 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
88 billion farm animals produce an enormous amount of waste
We needlessly raise and kill about 88 billion land animals a year[4], and all of them eat, drink, poop, and pee. About 80% of farmland goes to grazing and feed[3], and about 70% of the world’s freshwater withdrawals go to agriculture, most of it to those animals[1][2]. Year after year, they produce a large amount of solid and liquid waste, and in the U.S., EPA figures put their manure at about 13 times the solid waste of the human population[5]. That waste runs off into rivers and oceans and causes dead zones where nothing can survive. We don’t have to harm or eat animals at all.
Read full article →Farms cause about 78% of the nutrient pollution choking rivers and oceans
Poore and Nemecek found that farming causes about 78% of the nutrient pollution that starves rivers and oceans of oxygen, and that food production causes about a third of the acid rain that falls on land[1]. Most of that comes from growing feed and from farm animals’ pee and poop.
Read full article →
Our World in Data · water pollution per 1,000 kcal · Poore & Nemecek (2018)
Per calorie, meat and dairy pollute water far more than plants
On Our World in Data’s charts of water pollution per calorie, cow flesh, cheese, and farmed fish are at the top, and peas, nuts, and potatoes are near the bottom[1]. The extra pollution comes from the animals: the feed they eat and the waste they leave behind.
Read full article →70% of the freshwater we use goes to farms
Farming uses 70% of the freshwater we pull from rivers and underground[1], and most of that goes to feed crops and troughs, not salad[2]. When the water runs off the fields, it carries the waste with it.
Read full article →UK vegans caused about 73% less water pollution than high-meat eaters
In a study of about 55,000 people in the UK, vegan diets caused about 73% less water pollution than high-meat diets[1]. They also produced less climate-heating gas[1][2] and used less land[1]. Every bit of that extra pollution was avoidable.
Read full article →Articles
Farm animal waste is choking rivers and oceans
Farming causes about 78% of the nutrient pollution that creates dead zones in rivers and oceans, and farm animals in the U.S. produce about 13 times as much manure as all the human sewage in the country. Vegan diets cause about 73% less water pollution than high-meat diets.
Read full article →
Sources
Papers and datasets. Each card keeps its caveats, including small samples and single-animal cases.
[1]Science, 2018 · Meta-analysis
Food production causes about 78% of eutrophication and 32% of acidification
Poore and Nemecek found that food production causes about 32% of the world’s acidification on land and about 78% of eutrophication (nutrient pollution of water), and most of it happens on the farm. Even the lowest-impact animal products usually do more damage than plant-based substitutes.
[2]Our World in Data · Review
Farming causes 78% of the world’s ocean and freshwater eutrophication
According to Our World in Data, farming causes 78% of the world’s ocean and freshwater eutrophication (nutrient pollution of water). Farms also take 70% of the freshwater people withdraw.
[3]Our World in Data · Meta-analysis
Cow flesh, cheese, and farmed fish cause the most water pollution per calorie
Our World in Data’s chart of Poore and Nemecek’s data shows that cow flesh, cheese, and farmed fish cause the most water pollution per 1,000 kilocalories. Plant foods cause far less.
[4]Nature Food, 2023 · Observational
Vegan diets caused 73% less water pollution than high-meat diets
Scarborough and colleagues studied about 55,000 people in the UK and found that vegan diets caused about 73% less water pollution than high-meat diets. They also produced about 75% less greenhouse gas and used about 75% less land.
[5]Environmental Health Perspectives, 2007 · Review
U.S. farm animals produce about 13 times as much waste as the country’s people
Citing the EPA, Burkholder and colleagues report that U.S. animal farming produces about 133 million tons of manure a year by dry weight, about 13 times the solid waste in human sewage.
[6]Ecosystems, 2012 · Meta-analysis
Meat and dairy pollute far more water than pulses and grains
Mekonnen and Hoekstra found that the grey water footprint of meat and dairy, meaning the water needed to dilute the pollution they cause, is far larger than that of pulses and grains. Nitrogen and phosphorus run off the feedlots and the fields.
[7]Faunalytics / FAO
The world slaughtered 87,896,729,120 land animals in 2024
Faunalytics compiled the UN’s FAOSTAT data and counted 87,896,729,120 land animals slaughtered in 2024, up about 1.85% from 2023. The killing is growing faster than the human population.