Firehouse Subs is holding its H20 for Heroes event on Saturday from 11 a.m. until closing time at 11 p.m.
Anyone who brings in an unopened 24-pack of any brand of bottled water will receive a medium sub.
Cases of water donated will be provided to local first-responders and be distributed to those in need.
Firehouse Subs is located at 454 Bayfield St.