Use saltwater only if you distill it first. You should not drink flood water. In addition to having a bad odor and taste, contaminated water can contain microorganisms that cause disease such as dysentery, typhoid and hepatitis. You should purify all water of uncertain purity before using it for drinking, food preparation or hygiene. There are many ways to purify water.
None is perfect.
Often the best solution is a combination of methods. Two easy purification methods are outlined below. These measures will kill most microbes but will not remove other contaminants such as heavy metals, salts and most other chemicals. Before purifying, let any suspended particles settle to the bottom, or strain them through layers of paper towels or clean cloth. Bring water to a rolling boil for 3-5 minutes, keeping in mind that some water will evaporate.