Starting to get worried about the condition of my teeth now.

Last dental appointment was in march, absolutly no problems. Since then, a condition in my home water supply called "biofilm" started to affect the water. After some research, this was found to be a cause of tooth decay.

Lately I have known that 3 of my front teeth have started to become stained with brown markings and the only thing I can think of being a cause is biofilm - I brush my teeth 3 times a day and so if I am using infected water it seems likely.

Is there any way this can be remedied i.E. Will it eventually sort itself, is there any products I can buy, or is definatly a dental operation job?

Thanks for any help,

dave