Merely allow the solids to settle and drink the water off the top. Make certain you shut off the electrical energy or gas to your water heater well before emptying or it will be ruined! Crack an top faucet and open a lower hose pipe bib or tap to drain a handful of quarts of water out of your home’s piping.
Make use of water filters and treatment chemicals. I learned from experience that almost all anyone will drink from awful, scummiest water shortly after having gone without any water for over a day in harsh heat! If you need to vacate your property, carrying a personal supply of water on your back will be exceptionally challenging (at a gallon per person each day, a family of 7 would ingest 150 lbs of water in 5 days).
Flood waters are normally very contaminated with farm junk, human sewage, and commercial chemicals, so I highly suggest that you buy a bacteriological back-country-type water filter system that has a carbon center to also remove hazardous chemicals, bad tastes, and odors. You can chemically manage surface water with household tincture of iodine ( six drops per gallon) and pure chlorine bleach ( four drops per gallon) and permitting water to set for 20 seconds.
I produce these items for a lifestyle, so I understand what I am speaking about. Boiling for merely 1 minute will kill all water-borne living things, but will not do anything to eliminate poisonous chemicals, bad tastes, and odors.