It's all about their prime ingredient, the brewers say. Beer is 92 to 94 percent water, and the cleaner it is, the better the brew.
So their largesse is also about self-preservation.
"We don't want to stand on a soapbox and scream at people, 'Take care of your water, or your beer will be no good!' " said Bill Covaleski, cofounder of Victory Brewing Co. in Downingtown, which has given $16,000 from sales of its Headwaters Pale Ale to local watershed groups.
"But it does allow us to initiate dialogues," he said.
The same thing is happening nationwide, said Karen Hobbs, a policy analyst with the Natural Resources Defense Council, an advocacy group that in April launched Brewers for Clean Water.
The members - about two dozen so far - pledge to "stand up for clean water and the Clean Water Act." In June, they sent a letter to President Obama, urging him to do the same.
Beer, said Delaware Riverkeeper Maya van Rossum, "is another way to highlight for people why they should care about clean water."
Her group has received about $10,000 annually the last few years from Sierra Nevada's "Wild Rivers" campaign.
Both Flying Fish and the 16-Mile Brewery in Delaware have offered stouts celebrating - and benefiting - the Delaware Bay oyster.
For the last part of the brewing process, they add a net bag of oysters - shells and all - to the brew kettle. The mollusks add their tangy brine flavor, and later the brewers and friends eat the cooked oysters.
After the oil spill in the Gulf of Mexico, Dogfish Head Brewery in Milton, Del., came up with a Stop the Spill ESB, with a dollar from every pint going to cleanup efforts.
Every September the brewery holds the Dogfish Dash, a race to benefit the Delaware chapter of the Nature Conservancy, which has two publicly accessible preserves within a bike ride of the brewery.
Since 2007, more than $150,000 has gone to the conservancy, which state director Richie Jones said funds land protection.
With small groups, the money can make a big difference. Victory's funds allowed the all-volunteer Guardians of the Brandywine to start a stream monitoring program.
The $5,000 that's gone so far to the Brandywine Valley Association is "a nice number," said Robert Struble Jr., the group's watershed conservation director. "We can do a lot of work with that."
Even if the money isn't a game-changer, the recognition value is huge. Beer is turning out to be a new way for eco-groups to connect.
Many environmental groups are serious and "sciencey."
So "being able to talk about protecting drinking water over a really good beer is a new and fun way to do our outreach," said Tom Davidock, coordinator of the Schuylkill Action Network.
The SAN, a consortium of Schuylkill groups, gets some of the proceeds from sales of Stonefly IPA - named for the aquatic insect - by Saucony Creek Brewing Co. in Kutztown.
William Reed, co-owner of the Standard Tap in Northern Liberties, a bar that serves only local beer in kegs, said customers get it. People who are into craft brews are eager to know more, and when they see the environmental message, they respond.
The brewing companies often get something out of it, too - new customers.
Guardians president Tish Molloy recently described Victory's Covaleski as "such a neat guy" and said of Headwaters, "We drink it often."
Contact Sandy Bauers at 215-854-5147, email@example.com, or follow on Twitter @sbauers. Read her blog, "GreenSpace," at www.inquirer.com/greenspace