Water

Eating plants is the biggest water saving a household can make

By WhyStopHarmingAnimals.com

About 70% of the freshwater people pull out of rivers, lakes and aquifers goes to agriculture, according to Our World in Data[6]. Much less of it ends up in food people eat directly than that number suggests. Farm animals have to eat and drink too, and about 80% of agricultural land goes to grazing and growing their feed[2], so the bulk of agriculture’s water is spent on corn, soy and grass for cows, pigs and chickens. Taking meat and dairy off the plate removes that whole loop, and no other change to what a household eats saves as much water.

Where the water goes

A cow can drink over 40 gallons of water a day. That is the part people picture, and it is the small part. The same cow can eat over 100 pounds of plant food a day, and every pound had to be grown first, with rain and often with irrigation. Most of a steak’s water footprint never went near a trough[4]. It soaked into the fields that grew the feed[4].

Mekonnen and Hoekstra worked out the full water cost of farm animal products in a 2012 paper in Ecosystems[4]. They counted green water (rain taken up by crops and pasture), blue water (drawn from rivers, lakes and wells) and grey water (the water needed to dilute the pollution a product leaves behind). Per calorie and per gram of protein, animal products had far larger water footprints than starchy crops, pulses and most vegetables[4], and the main reason was the feed[4]. Their global average for beef comes to about 15,400 litres per kilogram[4].

The animal sits in the middle of the chain and loses most of what goes into it. It eats plants, burns most of those calories keeping itself alive, and returns a fraction as meat, milk or eggs. Every litre that grew the feed is charged to that fraction, which is why eating the plants directly is so much more efficient.

What the big datasets show

Poore and Nemecek’s 2018 study in Science pulled together food-system data from around the world[5]. It found that meat and dairy account for most of agriculture’s water pollution and a large share of its water withdrawals[5], and that cutting them is one of the largest water savings a diet can make[5]. Our World in Data charts the same dataset three ways: freshwater withdrawals per kilogram, per 1,000 kilocalories and per 100 grams of protein[6]. On each measure, most animal products draw far more water than starchy crops and pulses[6].

Diet studies point the same way. Vanham, Mekonnen and Hoekstra compared the water footprints of several diet scenarios for the European Union in a 2013 paper in Ecological Indicators[7]. A vegetarian diet had the lowest water footprint of the scenarios they modeled[7], and animal products drove the gap between it and the rest[7]. A review by Clean Water Action came to a similar place for households, finding that plant-based diets cut a household’s water footprint while improving health markers[8].

The tap is the wrong place to look

Most water-saving advice is about shorter showers, fixing leaks and turning off the tap while brushing teeth. Those help, but the water a household runs through its pipes is small next to the water built into its food, and the biggest block of that is the feed behind meat and dairy. Moving toward plant foods is the single largest water saving a household can make.

What the figures do and don’t show

Several of these sources are models and reviews rather than measurements taken in people’s homes. The EU study compared modeled diets, and the lowest one it found was vegetarian[7], which still includes dairy and eggs. Water footprints also add together different kinds of water. Rain falling on a pasture is a different resource from water pumped out of a shrinking aquifer, and it is the blue water that runs rivers dry. The comparison holds whichever measure you choose: per kilo, per calorie or per gram of protein, beans and grains come out far ahead of the animals that are fed on them[4][6].

Eating plants directly skips the detour through an animal, and most of the water goes with it[4]. Choosing not to harm animals turns out to be the most effective water conservation most people will ever do.