Karen

We definitely have lots of flouride in our Washington DC area water (along with an array of other chemicals) but my prosthodontist said the same thing: it's not enough flouride and not concentrated on the teeth and that flouride trays are the way to go.
If you do go that way, I recommend being sure to get a "gel" with a narrow nozzle and not a toothpaste type flouride - there was an interesting discussion here a while ago about using a syringe to make the toothpaste cream type work, but I find it easier to just buy the type that works right out of the little tube it come in.
Last but not least, while my insurance refused to pay for the flouride trays, they continue to pay for two full tubes of the prescription flouride each and every month with no quibble.
Charm