Beer is one of the world's most popular drinks. Even some of the earliest humans brewed – or made - beer.

　　One of beer's most important ingredients is water. Brewers say you need up to five liters of water to make one liter of beer.

　　If water becomes scarce, then, will people have to stop making beer?

　　Brewers have already thought of that possibility. So, in some cities, people are testing out beers made from collected and filtered rainwater.

　　They are also collecting rainwater and water from the beer-making process for use inside the brewery.

　　Sierra Nevada is a well-known brewery in California. It also has a new location in North Carolina. It uses rainwater for cleaning and flushing toilets.

　　Brewers understand the importance of saving water. If there is no water, there is no beer.

　　That is why Stone Brewing Company, near San Diego, California, worked with a local water treatment program to make beer.

　　The program is called Pure Water San Diego. It wants to provide one-third of the city's water by 2035.

　　Working with Pure Water, the brewery used purified water that came from wastewater. Wastewater is water that has already been used for showers, washing dishes or flushing toilets.

　　Stone is a large brewery. It has customers across the U.S. and Europe. Along with its original California location, Stone also has breweries in Richmond, Virginia, and Berlin, Germany. Some of their beers are among the best in the United States.

　　So it was a big deal when Stone released a special beer called Full Circle Pale Ale in March. Many websites and newspapers wrote about the beer. They reported that it was made from "toilet water." Local television stations recorded people's reactions as they tasted the beer.

　　The story went viral.

　　The mayor of San Diego took a sip, and said "that'll work, that'll work."

　　Brewer Steve Gonzalez described the beer by saying it had "caramel" and "tropical fruit" flavors.

　　Stone Brewing later wrote a blog post saying it was not happy with all of the news coverage – especially reports that centered on the idea of "toilet water." But it was happy that the experiment was a success.

　　The beer was only made for a special event. Stone Brewing is not permitted to sell it in stores or at the brewery's restaurant.

　　But other brewers around the country are taking notice.

　　Kevin Ryan created Service Brewing Company in the southeastern U.S. state of Georgia because he loved making beer for friends and family. They told him his beer was so good, he should go into the business. So he did.

　　Ryan knows how important water is to the beer business.

　　"The southeast is always back-and-forth between drought and recovering from drought," Ryan said. "As we can afford, we will try to be responsible consumers of that water. I think it's great that somebody who's established can use their platform to do the testing and demonstrate that you can make great beer with reclaimed water."

　　Ben Cook started Hangar 24, a brewery in Redlands, California. One of Hangar 24's well-known beers is a wheat beer made with locally grown oranges. He was glad that Stone Brewing's experiment got attention.

　　"I have a biology background," Cook said. "And water is water. It is H20, along with any minerals that are in it. I see no problem with it. But the public perception, because they don't know that it's just as clean as tap water, appears to be still pretty bad."

　　Cook said if his customers better understood how clean reclaimed wastewater really is, he would have "no problem" brewing beer with that kind of water.

　　"If there's something that's better for the environment that we can afford to do, we always opt in," Cook said.

　　Other American brewers have also experimented with reclaimed-water beer.

　　Researchers and brewers in the state of Arizona are working on a water-saving project. They received $250,000 to promote the use of reclaimed water. They are treating and using wastewater that will be used to make beer across the state this summer.

　　And last year, small brewers in Florida experimented with making beer from reclaimed water. They taste-tested their work at a large water-treatment conference.

　　I'm Dan Friedell.

　　And I'm Jill Robbins.

　　Dan Friedell wrote this story for Learning English. Ashley Thompson was the editor.

　　Would you like to taste beer made from reclaimed water? We want to know. Write to us in the Comments Section or on 51VOA.COM.