Water Damaged Documents and Photographs
The best thing to do is avoid water damage by preventive measures, especially in flood prone areas. Have a disaster plan ready. Have all your documents of significance in a ready state for evacuation.
(See below for links to YouTube videos on how to preserve water damaged collections).
How to deal with wet documents.
Try and deal with wet documents quickly! Preferably within 24 hours of being wet. If you cannot deal with them immediately you can put them into freezer bags and freeze them until you get time to deal with them.
Anything that has been wet in moist warm air for longer than 24 hours will have started to develop Mould (or Mold).
A definition from the Oxford dictionary.
Mould is a "wooly or furry growth of minute fungi on things of animal and vegetable origin that lie for some time in in moist warm air [ME (Middle English), f(rom). obs(cure). mould a., p.p of moul grow mouldy f. ON (Old Norse) *mugla, mygla]
Mould is very damaging to any organic based material (almost everything in an archive). Mould is also extremely dangerous to humans and great care should be taken when dealing with mould.
(More on dealing with mould later - Try a google search for other resources)
"Dealing with water" damage videos on YouTube
There are some very useful video links put together by "Preservation Australia," that were located thanks to the Australian Historical Societies Support Group newsletter after the 2011 Brisbane floods.
Category Name: Caring for collections
Link Name: Salvage of water damaged materials
Link URL: http://www.youtube.com/user/PreservationAust
Link Description: Video prepared by Preservation Australia