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Green, gray and blue water: Unexpected ways daily decisions grow our water footprint

Minnesota Department of Natural Resources
The headwaters of the Mississippi River can be found at Itasca State Park.

Afton Clarke-Sather, a professor at the University of Minnesota Duluth, discusses how consumption habits influence our water footprint and simple steps we can take to ease the pressure on our state’s water resources. Clarke-Sather is this month's featured speaker for "Practical Water Wisdom."

When most of us think about conserving water, we think about shorter showers or turning the water off while we brush our teeth.

A white man with glasses and a full beard smiles at the camera.a
University of Minnesota Duluth
Afton Clarke-Sather

Afton Clarke-Sather, a professor at the University of Minnesota, Duluth, shared his research demonstrating we can have a greater effect on conserving water by examining the food we eat, products we choose to buy, and how we manage our yards.

Take the test

One of Clarke-Sather's final exam questions for his students states, “What can you do to reduce your water impact?” Students who answer “turn off the water when we brush our teeth” haven’t been listening, he said.

“The amount of water that you use out of your pipe is actually much, much less than your total water impact from everything you consume,” Clarke-Sather said. “This is what we call your water footprint.

“ ... The biggest part (of your consumption) comes from the food you eat, the goods you wear, the manufactured things that you have, and even some of your things like your land use practices end up impacting water in much bigger ways than simply brushing your teeth.”

Cotton, for instance, is a very water-intensive crop. So, buying fewer clothes (or shopping used or wearing hand-me-downs) can have a significant impact on an individual’s water footprint. Similarly, using items through the end of their functional life (and washing items only when they need it) can reduce water use.

Researchers examining water use divide an individual’s water footprint into three “buckets,” so to speak.

“Blue water” comes from your pipes and is measured by a water meter. It’s the potable water you use to brush your teeth, make your coffee or take a shower. While this is the most visible and obvious way we consume water, it has the least effect on our overall water footprint.

Instead, our food consumption has the most drastic effect on our water use. This “green water” is water used to grow the plants and animals we eat. Animal protein has the highest water requirement.

Finally, “gray water” measures an individual’s water pollution impact. In the United States, this is typically minimal for residential homes.

But the crux of the issue, Clarke-Sather said, is how we choose to allocate our water resources.

On your plate

Eating locally can lower water use, benefit the local economy and reduce carbon emissions. Cutting back on meat or swapping proteins — along with reducing food waste — are ways to water footprint, Clarke-Sather said.

“Different types of meat have much different demands,” he said. “Pork and chicken have much lower demand on average than beef.”

A cow stands in a snowy field in Minnesota. It is looking at the camera. The image is captioned "Local Foods".
A cow stands in a snowy field in Minnesota.

The range is wide, however: the most-consumptive chicken products will use more water than the least-consumptive beef products.

For instance, a range-fed cow raised in Northeast Minnesota will certainly have some water footprint, but it dwindles in comparison to water needed to raise a corn-fed cow in a feed lot in Kansas. Similarly, Wisconsin dairy cows have a much smaller water footprint than dairy cows raised in California.

Instead of eliminating meat entirely, Clarke-Sather opts to be conscious of the types of meat he purchases.

“I will say right now that I love eating meat,” Clarke-Sather clarified. “I love being a meat-eater. I’m a carnivore myself.”

Choices like dairy-free milk also have impacts. Almond milk requires a lot of water to make and is typically produced in areas that are already water-poor. Oat milk, by contrast, doesn’t require as much water to produce and is grown in places with more water.

On your lawn

Pollution impact on water sources is another way to measure a footprint.

Residential source of pollution tend to be minimal, Clarke-Sather said. Septic tanks (well-maintained and compliant ones, at least) and municipal wastewater plants do a good job filtering out pollutants.

Runoff, however, can pollute local waters. Nutrient runoff from lawn fertilizers can have a drastic impact on nearby water quality.

A short patch of green lawn is bordered by a native garden and shoreline buffer. A lake is visible in the background.
Minnesota Department of Natural Resources
A short patch of green lawn is bordered by a native garden and shoreline buffer.

“We’ve really kind of chosen this aesthetic from about a hundred years ago. We decided we wanted our landscape to look like you could spot a sheep out of rural England anywhere, and that’s what we’ve gone with in so many places,” Clarke-Sather stated.

For those not worried about the visibility of wayward sheep, planting shoreline buffers can help reduce pollutant runoff. In addition, replacing turf-grass lawns with native plants is an appealing option, particularly for those interested in wildlife.

These options also reduce the amount of time spent sweating behind a lawnmower, Clarke-Sather pointed out. Personally, Clarke-Sather said he does keep a patch of lawn in his backyard for his kids to play soccer. He doesn’t fertilize it and has replaced the rest of the yard with native plantings.

Homeowners in Las Vegas and other areas have found themselves stuck between homeowners’ associations requirements for green lawns and the cost of maintaining one. Some have turned to Astroturf for a cost-effective and HOA-compliant option.

“I still think that’s kind of a bit of absurdity, because there are a lot of good options with xeriscaping,” Clarke-Sather said. “One of the interesting things out West in these deserts is there are a lot of cultural ideas around this.

“For instance, in Tuscon, Arizona, for the most part people do not do lawns. There, they go with native desert vegetation. Whereas in Phoenix, they’re really big on green lawns that require a lot of water for irrigation.”

Xeriscaping Explained

For many Minnesotans, the risk of serious drought feels far-fetched. The state features vast freshwater resources — but much of the state’s water comes from groundwater sources. So, despite its storied 10,000 lakes, Minnesota still experiences droughts. Having an irrigated lawn during lean times can become a substantial financial investment.

A model house sits on top of three red cubes with the letters "HOA" spelled out. In the background, an out-of-focus person fills out paperwork.
Homeowner's associations can greatly affect a community's water footpring.
A model house sits on top of three red cubes with the letters "HOA" spelled out. In the background, an out-of-focus person fills out paperwork.

The big picture

In closing, Clarke-Sather encouraged listeners to think beyond the individual level to the institutions governing their lives, and to become civically engaged in organizations like home owners or lake associations.

“We tend to put a lot of stuff on the individual and say, ‘It’s all your fault,’” he said. “ … We have a lot of forms of local government that actually end up asking us to do things that have a pretty big water footprint, and so being active in your community around the water issues is the other thing that can do something to reduce your water footprint. It’s not about your direct consumption, but it is about how we make choices as a society.”

To view Clarke-Sather's full presentation as part of Itasca Waters’ Practical Water Wisdom series, visit

Funding for this project was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR).

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Charlie Mitchell (she/they) joined the KAXE team in February of 2022. Charlie creates the Season Watch Newsletter, writes segment summaries for the website, and coordinates our Engaging Minnesotans with Phenology project. With a background in wildlife biology, she enjoys learning a little bit about everything, whether it's plants, mushrooms, aquatic invertebrates, or the short-tailed shrew (did you know they can echolocate?).