Ecolab, which makes its Just 100 debut at No. 22, logged $15 billion in revenue last year from selling water-treatment chemicals and cleaning supplies, including hand sanitizer, to companies including Microsoft and Colgate-Palmolive. This spring, it modified production lines at seven of its water-treatment plants to increase its hand sanitizer output. It also donated $3 million worth of its alcohol wipes and disinfectant sprays to health-care providers in its St. Paul, Minnesota, home and around the world. “Our team is proud of the way we stepped up our efforts when our expertise was needed most,” CEO Doug Baker says. The market agrees: Ecolab is up more than 50% since stocks bottomed out in March. Bill Gates is a fan, too; the billionaire owns a 14% stake through his investment firm, Cascade.