A safe rule to follow: Consider any area that came in contact with flood water unsafe until thoroughly dried, cleaned and disinfected properly. Water passing over submerged areas will pick up an unimaginable number of contaminants including, but not limited to, dangerous strains of bacteria and fecal matter from animals.
Sorry this posting has no length, but the point remains: Submerged wells SHOULD get tested before returning to service. Otherwise the risk of contamination by flood water WILL present itself.
Even if you think the cap on your well could withstand the force of 100 hurricanes, don’t ever forget that your neighbor’s well cap may not have received inspection in a number of years and… flood water creeping in through their faulty well cap will eventually reach the aquifer — from which your well draws its water.
Once flood waters go down, owners of private water wells should pump out their wells, allow them to refill/recharge naturally, and disinfect them before using any water they produce for drinking, cooking and in some cases even bathing.
Oh, and of COURSE we suggest getting the well water tested for, at the very LEAST, coliform bacteria before returning it to service.
Contact your local health department to see if they have discounted or free well water testing options available. Many localities will make such options available to residents after flood waters have ravaged an area.
Do-It-Yourself Test Kits for Bacteria
While we STRONGLY suggest testing for bacteria on a regular basis using at-home drinking water test kits such as the EPA Compliant WaterWorks EZ Coliform Cult Bacteria Test Kit which follows the APHA, Standard Methods, 20th Edition, 9221 D, screen test for total coliform in potable water, after a flood situation we ALWAYS suggest having a certified water testing lab analyze the water for bacteria.