If there is potential that the floodwaters are contaminated by sewage, chemicals, or other hazardous items, cleaning and disinfection of walls, hard-surfaced floors, and other household surfaces is critical to remove any bacteria and viruses that could be present. It is important that surfaces that have been in contact with contaminated floodwaters be disinfected. You can disinfect with a solution of 5 ml of household bleach mixed with 1 L of water.
When using a disinfectant, be sure to ventilate the room by opening windows and wear rubber boots, waterproof gloves, eye protection, and a N95 respirator (mask) as strong solutions may irritate skin and cause respiratory symptoms.