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My hands shook as I brought a glass of Reuse Brew to my lips. I don't normally hesitate to drink a beer, but as the name suggests, Reuse Brew was made from recycled wastewater -- that's right, the stuff of toilets. In my mind, I knew it would be sanitized and would likely taste pretty good, but it still took every ounce of willpower I had to take that first sip. I mean, it's not everyday you drink poop beer.

I'm in Berlin for the IFA tech show this week and I had just toured one of the city's wastewater facilities. This particular wastewater plant partnered with a water technology company called Xylem to make Reuse Brew as part of a special project to raise public awareness and public interest in recycled water. While touring the plant, I had a chance to see the water at all stages of purification, including the open reservoirs of chunky, feces-filled sludge.

The smell during the first part of the tour was one of the most intensely awful things I've ever experienced. I felt like I was in a room in which a million people had just gone to the bathroom, and that image isn't far from the truth, as the facility treats the wastewater for 1.3 million Berlin residents.

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Later in the tour, I got to see all of the fascinating technology involved in purifying the water, including a machine that makes ozone to break down waste on a molecular level. Another machine uses specialized carbon filters that supposedly eliminate 99.999% of all pollutants and chemicals.

On some level, I knew the water was clean, but my hands shook anyway. I couldn't get that smell out of my mind as I brought the beer to my lips.

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I shouldn't have worried so much. The beer was great. It was a malty brown ale with nicely balanced hops and carbonation. It was brewed as a traditional German Altbier. While the color didn't help given the circumstances, if I had tried it in a bar, I would have had a couple of glasses. As it stands, I drank the very last bottle in existence and was satisfied by every sip.

While Reuse Brew itself was just a one-time experiment, the tech behind it could have important implications for the future of beer and the future of drinking water in general.

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The problem of scarcity

"The fact is, most cities are overly reliant on a single source of water," said Joe Vesey, Xylem's chief marketing officer, while talking with me about the need for projects like Reuse Brew. "Water is probably the most important ingredient in a supply chain for a city."

Vesey detailed examples from the past few years where places such as Sao Paolo, Cape Town and the Ganges river basin each faced a water supply shortage that threatened to leave millions of people without a source of fresh water.

"You either have a quantity problem, which is scarcity driven by climate change, or you have a pollution-oriented problem that could be putting a stress on water supplies," said Vesey. "At the end of the day, there's more and more people on Earth and a fixed water supply. Water is a fixed, scarce resource."

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Municipalities can pay to import clean water or import seawater and go through the process of desalination so that it's drinkable. Vesey noted that both solutions are much more expensive than simply cleaning wastewater, which is a supply naturally generated by any city.

"We clearly see that wastewater is more and more considered to be a valuable resource," said Jens Scheideler, the global manager of the Reuse brand at Xylem.

Believe it or not, the biggest obstacle isn't even the technology. The wastewater plant I visited has been treating water for years and reintroducing it into rivers and lakes. In Berlin, the soil beneath the groundwater provides a natural filter that cleanses the water on its own over the course of several years.

The population's increased use of medications makes filtering water even more challenging, and that's where Xylem's tech comes in handy. Specialized ozone filters activate and break up the molecules of chemical waste that carbon filters then remove. This step isn't necessary for nonpotable water -- simpler, lower tech treatments work well enough for irrigation.

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"Wastewater contains the nutrition you need to foster and grow plants. You have nitrogen and phosphorus already present in the wastewater," said Scheideler. "Even in Germany, there's a mind shift toward using wastewater for agricultural purposes."

The advanced steps enabled by Xylem's technology work well enough to make the water safe for human consumption. Similar projects are already up and running in places like California and Singapore. Water treatment facilities regularly partner with Xylem and similar tech companies to find increasingly effective and efficient solutions.

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The biggest problem with using recycled water is the "yuck factor." I know from firsthand experience that it's really hard to convince yourself to drink water that used to be full of human waste. Beer puts a fun spin on the tech and gives people a reason to take the leap by taking a sip.

Trust and the reason for beer

Engaging and educating the public about the process is a key part of Xylem's plan. Beer is an important part of German culture and Reuse Brew in particular helped the company gain attention at a local conference on water. The beer was a hit, and everyone wanted to try it. I was lucky to be able to have a sip myself as the rest of the bottles are gone.

Reuse Brew checked all of the right boxes. Germany has a strict purity law when it comes to beer called Reinheitsgebot. This law dates back to the 1500s, and Reuse Brew met the standards.

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Jan-Karl Nielebock, Reuse Brew's food and beverage application manager, said the Altbier had to pass several tests to meet Germany's high standard. The law "of course asks for drinking water quality and asks for no health risk caused by drinking the water and this is what we had to prove several times," he said.

They had the German Federal Ministry of Health and local universities run lots of analysis on the beer itself, and all signed off on the safety of the final product.

Brewing beer involves cooking water with malted barley then boiling it with hops. The boil in particular can help clean the water further.

"Beer brewing in the past was the classic way to convert shitty water into a drinking water source," said Scheideler. "The beer brewing process itself is also helping to provide more reduction of viruses and bacteria if anything would be left. It was medieval times when this was needed. The water we produced was already close to being sterile."

Xylem and Reuse also make wine and vodka with recycled water. They've partnered with the English Premier League's Manchester City to turn rainwater captured from the stadium into beer served at matches by Heineken.

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Educating the public and softening public opinion through fun events is key to widespread adoption. Vesey pointed out that surveys in which the opinions of recycled water increased exponentially after participants were taught about the tech behind the process.

"There's no yuck factor when you pick up a fork or use a glass," said Vesey. "People are aware of soap and what goes into cleaning dishes." He pointed out that there's really no such thing as new water. All water on the planet has likely already been consumed by someone at some point. "Most water is recycled constantly, over and over." He called the Reuse process "the dishwasher step."

What's next

Berlin isn't the only place making beer from recycled water. Last month, four breweries in Louisville, Kentucky partnered with a nearby plant to make beer from treated wastewater. Xylem and other breweries are part of the Pure Water Brewing Alliance, which is an ongoing project to make beer more sustainable by using treated wastewater.

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Branding is another key part of the plan. San Diego calls its recycled water "Pure Water." Singapore uses the term "NEWater." After some hesitation, Vesey mentioned older terminology like "toilet to tap" and noted that the phrase could well kill the initiative.

The science is still being developed as Xylem and others look to make it increasingly efficient. At the water treatment plant in Berlin, we saw different sized filters acting as a tiered proof of concept. The smallest filters gave them the blueprints for the next size up. But the ozone machine from Xylem and the carbonation filters only clean a small portion of the water of the plant.

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Even at its current stage, Xylem and Reuse Brew are acting as pilot projects before potentially implementing a system like it at a larger scale. Reuse Brew already showed it works, but Xylem and scientists at the Berlin wastewater facility are working constantly to push the purity percentage even further and make the system more energy efficient as well.

The science, however, isn't the biggest barrier to success -- that's the mentality of the people that need to drink the finished product.

Even after seeing all of these pieces in action and hearing how effective the process was, I was hesitant. My problem was the proximity to smelling the water at the first stage of the process. Even if you told me what the beer was, I doubt I would have had as much trouble taking that first sip if I hadn't just smelled the plant where it was produced. The odor made me think I was on the brewery tour from hell.

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Once I got past my hesitation, I was glad I tried it. Two of my colleagues had a sip and liked the beer as well. It was well balanced throughout with a malty character and a smooth finish. Smell is an important part of taste and I even liked the way the beer smelled. I just had to push that other odor out of my mind.

Drinking beer made from recycled water in general will be easier for me as I've had it now and I can trust it enough to distance myself from the source. I'd have no problem drinking another glass of Reuse Brew. That trust is key. Xylem is engaged in an important process that could be a necessary part of keeping future cities supplied with plentiful drinking water. Thankfully, at the forefront of this experiment, the water is clean and the beer tastes great.