Firehouse Subs invites guests nationwide to join its effort to hydrate local heroes and communities with the eighth annual H2O For Heroes bottled water collection drive. On Saturday, Aug. 3, Firehouse Subs restaurants will offer one medium sub* to each guest who brings in at least one unopened, 24-pack of bottled water. The water benefits local fire and police departments, emergency victims, senior and community centers, and more, to aid those in need of water during the hot summer months when dehydration and other heat-related illnesses are most threatening.