Earlier this year in a Costa Rica library, around 250,000 rare books and newspapers - many dating from the 17th century - were damaged by floods and resulting damp.
For collectors of rare books, this scenario is nothing less than a nightmare.
That's why, as with first aid techniques, it is a good idea to have a plan in case the worst happens. So here are some tips.
If the information on the documents is the most important thing, your problem might be solved by simply photocopying the pages (although your local library or newsagent may not thank you for turning up with text soaked by a leaky toilet).
In other cases, the best course of action is: don't panic. A closed book which has just been splashed with clean water can be wiped with a dry cloth, with a good chance of no serious repercussions.
Books published before 1840 generally absorb a lot more water, which makes the problem more serious. The more water that is absorbed, the higher the chances of significant swelling and mould.
If the water is contaminated, the chances of mould can be reduced by rinsing the book with cold water - although this is a job best left to a professional.
For books damaged by particular polutants, there is much professional expertise available.
Professionals might use ozone chambers to remove stains and odours, or use freeze-drying which both destroys mould and removes water.
However, until the worst happens, don't leave your books on the ground floor if you're anywhere near water.
And invest in a dehumidifier if you think there is any risk of damp.