Boots Chemists in Falmouth suffered flood damage on Wednesday night, forcing the branch to close until Friday afternoon.
Firefighters from Falmouth were called on June 11 at around 10.30pm to the Market Street shop after it was reported that water was coming down from the ceiling onto electrical equipment.
One crew crew stood by to await Western Power technicians who isolated the equipment.
On Thursday morning, staff at the doors of the store were turning customers away and explaining about the closure.
A Boots UK spokesperson said: "The Boots store on Market Street, Falmouth will be closed until Saturday due to electrical repair work being carried out in the store.
"Prescriptions will still be dispensed at the front of the shop in the mean time, and we thank customers for their patience whilst the work is being carried out."