The building is owned by South West Water and the museum's lease expired at the end of last year.
The trustees want to raise enough money to buy the building.
The museum contains exhibits from Exmouth's heritage, dating back hundreds of years, which would have to be given to other collections outside the town.
New Lord Mayor’s pride in ‘thriving’ Exeter
Plymouth McDonald's wants 24/7 opening hours
Village’s only pub could close permanently
Government grant helps kick-start Oldway Mansion repairs
Devon plant firm digs in over land row
Torquay father’s concern as son held by Israeli forces
