Here's a list of communities which have rejected fluoridtion more than once:
Davis
5 times
Carmel
2 times
Los Angeles
4 times
Los Altos Hills
2 times
San Carlos
3 times
San Diego
3 times
Sacramento
3 times
Menlo Park
2 times
Redwood City
2 times
Burbank
2 times
Sunnyvale
2 times