You shower every day, brush your teeth, and drink plenty of water for health and well being. You house, on the other hand, doesn't achieve great health through water but rather can be horribly damaged by burst pipes or the introduction of flood waters. Once water penetrate the visible areas of the home, it gets behind the walls and under the floors where there isn't enough airflow for it to dry where beyond rot it can cause permanent damage.
Mold and Mosquitoes
A worse problem than structural rot is the mold that forms with moisture. Mold spores are already present in all organic material and just need a water source to grow. Once it begins to grow it spreads throughout the house and into the air, causing a number of health problems. A healthy adult may be able to live with mold for a short period, but people with asthma, the elderly, and children are especially susceptible to the effects of mold poisoning. A worse aspect is mold poisoning is actually an allergy so you never develop a tolerance to it but rather suffer the effects worse as time passes and exposure continues.
Further problems with moisture involve mosquitoes and bugs. The unsanitary conditions cause disease and mosquitoes carry the illness. The presence of bugs draws more bugs which burrow into the structural wood, and in turn attracts rodents. The problems of mold and mosquitoes by their nature cause even worse problems to occur.
Immediate Mitigation Process
After a flood, the immediate process is to begin drying out the moisture. This will involve cutting out sections of drywall and removing insulation. Heavy industrial fans and dehumidifiers will be set up to speed the drying process before too much damage can occur. The process typically takes 3-5 days, then a contractor can assess the damage and form a plan to repair it.
The repairs will consist of checking for any further moisture, water sources, and damage caused by the initial flooding. The structural framing in the affected areas will be sanitized or replaced as needed and insulation replaced. A full electric and plumbing inspection will assure those systems remain safe, then the walls will be be closed off with new drywall and paint. Flooring will be replaced assuming the old can't be reused as is often the case, then the job is finished so you and your family can return to life as usual.