Should I stock up on bottled water in case terrorists taint the public supply?
It's not a bad idea to have bottled water on hand in case of an emergency due to weather or otherwise, however intentional contamination of the water supply would be difficult and highly unlikely.  Water is chlorinated and tested constantly before being pumped into people's homes, and it moves in such massive quantities that a bioagent probably would be diluted before any harm was caused.

 

Are there vaccinations I can get to help me fight infections caused by a biological attack?
There are vaccines to prevent anthrax and smallpox – two of the most likely bioagents – but there are problems with both. Anthrax vaccine is available only to the military, and some experts question its effectiveness. Smallpox immunization was routine until the early 1970s, when the disease was eradicated and the vaccine's effects lasted only about five years. Limited supplies are still available, but not nearly enough to routinely vaccinate everyone.

Would a gas mask do any good during a biological attack?
It might help if you've been fitted for a gas mask so it is airtight, which is something the average person cannot do, and if you constantly wear it 24 hours a day.  Also, the effectiveness of a gas mask depend on many variables with the incident, including:  the kind of attack, location, and wind conditions.  These factors are so significant that public health officials say it would be a waste to try to defend against bioterror attacks with a mask.