When many people get sick-people tend to panic. Remember though, statistically, the numbers were lower than most grade-school stomach flu outbreaks. But your local grade school is not of interest to the nightly news!
I am a nurse, and deal with prevention techniques every day. I manage to rarely get ill, and never bring home bugs to my DH and kids by following a few simple rules.
-First, of course is handwashing. But since the average person does not wash properly (a 3 minute scrub), bring an antibacterial gel with at all times, and finish off with that. Bath and Body Works has a whole line of wonderfully-smelling antibacterial products.
-Next, for adults, rinse with Listerine whenever you get the chance for a full minute if you can stand it. For my kids, I dilute it, but this is at your own discretion.
-Never, under any circumstances put hands in your mouth, and discourage your kids from doing so. Often this is unconscious, so practice for a few weeks prior to cruising.
-Use flush and faucet and bathroom door handles with a tissue on your hand. People expend enormous energy covering toilet seats, where they are least-likely to contract a virus, but touch faucets freely.
-Be well-rested prior to the cruise, and drink plenty of plain old water. As a general rule, take your body weight, divide it by 2, and drink that number of ounces per day. So, for a 110 pound person like myself (

I would need to drink 55 ounces of water per day. Other fluids really don't count.
-Eat a healthy diet and take vitamins daily, and for adults, a B Complex and extra C helps build your immunity. Start now-it's flu season!
As for bottled water...It truly isn't the water that spreads Norwalk virus. It is the teechnical name for common stomach flu. The water is very safe-the CDC says so, and their standards are extremely high. The problem with vacationers is that people spend their hard-earned money on non-refundable trips, then feel obligated to take the trip, even if they know they are sick. Then, they spread highly contagious diseases in places where people spend time in close proximity. Some people even allow their non-potty-trained children to swim in the pools without diapers (UGG).
So, the message is-if you are sick, call
DCL, they would probably rather switch your cruise than risk the bad publicity. If a member of your family get sick on the boat, seek medical advice immediately, and take extra precautions to protect yourself and other cruisers.
And above all-if you are healthy now-don't worry! It's not good for your immune system!