Assess the areas that have been damaged on your own. Write down where the damage occurs and a short description of it. Your description might include "basement, floors and walls" or "kitchen cupboard under sink." Describe exactly the type of damage, whether it is just water on a concrete floor that must be cleaned or whether the area has been corroded and damaged.
Take photos of the area that has been damaged. If possible, wait for the water to recede to do so.
Record and take pictures of any items damaged or ruined in the water. Separate these into two piles: those that can be fixed, such as plastic toys that can be cleaned, and those that need to be replaced, such as carpets or wooden furniture.
Contact several water cleanup agencies in your area by phone, and read them the list of damages. Ask them to give you an estimate of what it would cost to clean up and repair the items.
Find the items that need to be replaced in a store or online. Add the replacement cost of each item to your total estimate for clean up and repair. This is the computed cost for water damage clean up and repair.