How would you feel if you were on a cruise and had to pay nearly $4 in order to have water with a meal? Not breakfast, but lunch and dinner - and that's $4 each meal! The cruise is 11 days, so that's about $85.
The water on the ship is perfectly good, but they've decided that in the dining room - there is only one - you can only drink what you buy there. That's reasonable with alcohol and soft drinks. But they won't bring you a glass of ordinary water, just sell you half a liter of bottled water.
In July, my husband and I took a wonderful cruise from Dover, England, to the Shetland Islands, Faroe Island, four ports in Iceland, and two in Norway before returning to London. It was a small cruise ship and I am now spoiled.
I'd bring my own water on board. $4 is excessive. Start researching other cruise lines and see what their policies are. There are so many hidden fees to cruises. The thing with cruises: they can have too many countries involved. They might fly the flag under one country, employ those of another country, charter under another -- there was an expose of a woman being raped on board and it was impossible to prosecute because of all the countries hoops to jump through.