Trying to find this with someone else- the unfrozen people don't do anything for fun, they just work, and the water is drugged so they don't reproduce but every year or so(not sure exactly how often) it's changed to make a mating season. There's a librarian that helps the main character, and the engine is damaged so they're just drifting through space but most of the population doesn't know it. At one point one of the characters(I think it switches between first-person perspectives) is panicking about something so he drinks water to calm down. I think at one part there's a ceremony thing where children are singing and someone sets off an explosive but that might be a different book or movie. I read it in the US, they read it in Germany, both around 2010-2015.