What You Need to Know About Health Hazards After a Flood

(Psst: The FTC wants me to remind you that this website contains affiliate links. That means if you make a purchase from a link you click on, I might receive a small commission. This does not increase the price you'll pay for that item nor does it decrease the awesomeness of the item. ~ Daisy)

A flood is a disaster that just keeps coming back to haunt areas affected by it. As the waters recede, it doesn’t mean that the risk of illness is over. After a flood, clean-up itself can be fraught with hazards.

As if the loss of life and property isn’t enough, there other many hazards that arrive with flooding and persist long after the initial rise in water levels.

There are several diseases and myriad other health concerns that go hand in hand with freshwater flooding, and no matter where you live there are risks that can cost you your life that have nothing to do with drowning.

Lizzie Bennett, a medical professional and the author of the UK blog Underground Medic, compiled a comprehensive list of flood hazards. This is one to print out in and put in your preparedness binder to have on hand should you ever find the waters rising near your home.


The floodwaters are likely to be full of debris which can cause injury but it’s what’s lurking unseen in the water that can cause really cause problems. The power of water is unbelievable. Just a foot depth of fast flowing water can knock an adult of their feet, and less than that will knock over a more infirm individual. That amount of force can carry things along for a considerable distance. What’s more, in deeper water there is no way you can know what lies under the water.

Making your way on foot through murky water is really best avoided. Apart from injury, or even getting a foot caught up and not been able to free yourself, the water can host a number of diseases that can sicken or even kill you.

Trees, branches, concrete, vehicles, grocery carts and practically anything else you can imagine will be floating around or hidden beneath the water.


As I said previously the force of moving water is irresistible and it’s not only people that are swept away. Chemicals, even when stored properly in non-flood conditions, are likely to get into the water. Some, such as petroleum products are visible as a slick or film on the surface of the water, while others are totally invisible.

Caustic substances, solvents, inks, paints, and anything else you can think of are going to be mixed into the flood waters. Even though they will be massively diluted in such a high volume of liquid, they’re still there and will cause major problems if ingested. Some heavier than water toxins will collect in depressions as the floodwaters recede and those puddles, magnets for children, will contain much higher levels of toxins in the residues left behind as the waters evaporate.


Power lines, particularly in those areas where electricity cables are supported by wood telephone poles, can be a major hazard. Electricity can arc a considerable distance and lines in standing water can electrify a large area.


Most snakes, given a preference, would opt for dry land. Any incidence of flooding will see them seeking dry spaces, be those spaces natural areas unaffected by the floodwaters or the upper floors of buildings. Care should be taken when moving boxes etc that may have been stored on the upper floors of properties.

Acetaminophen kills snakes,  and just 125mg is usually enough. Half of a standard 500mg tablet would make sure they die. If you have rodents on returning to your property trap as many as you can, bait them with acetaminophen, and leave them for the snakes, who will enjoy their free meal.

This tactic was used to great effect in Guam. You can read about baited mice getting dropped by parachute here.


Rodents will naturally seek out higher drier land when floods hit. It’s not uncommon for there to be a ‘plague’ of mice and rats in areas around the edge of a flood as the rodents seek out new homes. As with snakes, they will often move into buildings, naturally gravitating towards the dry upper floors. As they will eat anything, food left in homes will draw them, even if it is wet. Snakes, of course, feed on rodents, and with both groups having ample food their numbers will only increase unless they are dealt with promptly. Clearing up after a rodent infestation is a hazard in itself and great care needs to be taken due to the risk of contracting hantavirus.


Leptospirosis is a zoonotic disease, which means that it can be passed from an animal species to humans. Rodents carry leptospirosis, so anything that brings them into closer than usual contact with humans poses a greater potential for infection.

When flooding occurs, rats and mice will always seek out drier ground in which to nest. As rats and mice are incontinent, they leave a trail of urine wherever they go. Until this urine is totally dry it is able to pass leptospirosis to humans via cut, scrapes, and abrasions on the skin. Andy Holmes, a British Olympic rower, died of leptospirosis in 2010. He had a small graze on his finger and it’s thought that is how he contracted the disease. He had been rowing on the River Severn a few days before he first became sickened with a flu-like illness. He went into kidney failure and died within a matter of days.

When cleaning up after a flood event, be sure to cover cuts and scrapes with waterproof plasters. Wear waterproof gloves and thick-soled boots to protect your feet and ankles. Long trousers are a must. If you get a cut when cleaning up after a flood, stop what you’re doing, squeeze the cut to force as much contamination as possible out of the wound, wash the area, and cover with a clean waterproof dressing.

Typhoid Fever

Caused by the bacteria Salmonella typhi, typhoid fever is a life-threatening illness. People infected with typhoid carry the bug in their intestines and shed it in their feces. Food or drink prepared by a typhoid sufferer can pass on the disease unless they have scrupulous hand hygiene. Although not a common disease in the United States sporadic cases do occur, usually in those who have traveled abroad.

Salmonella typhi gets into floodwaters when sewers overflow and pipes fracture.  Raw sewage is frequently mixed with the floodwater as drains and sewers fail to cope with the sheer volume entering the system. Once it’s in the flood water, food contamination is highly likely, either by people getting it on their skin and then preparing food, or by food supplies getting contaminated directly by the water. As well, contaminated water getting into the fresh water supply is a major source of infection.


Again, this is another uncommon disease in the United States, but cases are reported in people returning from areas where the disease is endemic. Like typhoid, it would be present in the water if infected sewage had entered the floodwaters.

Vibrio cholerae is a rapid onset intestinal disease that is immediately recognizable. The victim produces massive amounts of watery diarrhea and vomits profusely. Without rapid medical intervention, death can occur in just a few hours due to massive dehydration and shock.

As with typhoid, it is most frequently contracted when one consumes contaminated food and drink. Cholera gets into the water and can contaminate food and the skin of those who prepare food. Flood waters getting into drinking water supplies will spread the disease rapidly amongst those using the source for drinking or food preparation.


This is a worldwide disease that causes tens of millions of infections each year across the globe. Animals and humans both carry the bacteria that causes the disease. It will certainly be present in any flood waters where animals have defecated or when human waste has gotten into the floodwaters. As with any flooding, contamination of drinking water is commonplace, particularly in areas where wells or boreholes are used for drinking water.

Necrotising Fasciitis

This is a horrendous condition commonly called ‘the flesh eating bacteria’ in the media. It’s rare but is one of the most awful diseases you can imagine. The most common bacteria to cause the disease is the Staph A group of bugs. Doctors advise that those with cuts and abrasions should not use whirlpools, hot tubs, etc. unless the wound is well covered with a completely waterproof dressing. Hot tubs are spotless compared to floodwaters.


There are several types of malaria, some more serious than others. The Plasmodium falciparum and Plasmodium vivax varieties are the most serious. Malaria is spread by the Anopheles mosquito. Only the females spread the disease. Standing water is a mosquito magnet because it is where they lay their eggs. Just a teaspoon of water can contain hundreds of larvae.

When the floods subside and small puddles are left, mosquitoes will seek out these puddles to lay their eggs. If you get enough bites your body becomes used to them. You no longer itch and the bites often produce no bump, which  means people are oblivious to the fact that they have been bitten.  This increases the risk of having malaria for some days before seeking medical assistance.

Any other mosquito-borne illnesses will be spread in exactly the same manner. These include dengue fever, yellow fever, and Zika.

The list of illnesses that are caused by waterborne pathogens is a long one, way beyond the scope of one article. For a much more comprehensive list click here.

The aftermath of flooding doesn’t stop at damaged buildings and loss of life.

The effects are far-reaching, well beyond the diseases listed and the initial damage and death we see on the news.

  • Farmland can become contaminated as sewer waste from towns and cities washes over the fields.
  • Drinking water supplies will be unreliable until treatment plants are fully decontaminated and up and running to current safety standards.
  • The food supply chain will be affected when delivery trucks can’t access flooded areas.
  • Infrastructure will have to be checked for safety. Roads and rail links may be out of action for some time.
  • Work, education, and childcare will all be affected to some degree.
  • Fuel supplies at gas stations will not be reliable.
  • Emergency services are not immune to flood effects…help may not be on the way.

Are you ready for this? Could you cope if flooding hit your area? It’s not an easy thing to prepare for because all of your carefully stockpiled supplies could be ruined. In cases like this, the best preps you can have are the knowledge needed to keep your family safe and excellent insurance. (If you live in an area that is likely to flood, do yourself a favor – check to be sure that your coverage meets these standards.)

Picture of Daisy Luther

Daisy Luther

Daisy Luther is a coffee-swigging, globe-trotting blogger. She is the founder and publisher of three websites.  1) The Organic Prepper, which is about current events, preparedness, self-reliance, and the pursuit of liberty on her website, 2)  The Frugalite, a website with thrifty tips and solutions to help people get a handle on their personal finances without feeling deprived, and 3) PreppersDailyNews.com, an aggregate site where you can find links to all the most important news for those who wish to be prepared. She is widely republished across alternative media and  Daisy is the best-selling author of 5 traditionally published books and runs a small digital publishing company with PDF guides, printables, and courses. You can find her on FacebookPinterest, Gab, MeWe, Parler, Instagram, and Twitter.

Leave a Reply

  • THE most important thing is missing from this chilling thread: maintaining your immune system and keeping a level head, a.k.a. not panicking.

    I grew up alongside the muddy Mississippi River (downstream from an industrial city) surrounded by farm country. I played, swam, fished and hunted, in and along flood-waters most all my life. I used to be what the Locals call, ‘a river rat’, which is a bit like being Tarzan part-time and a dog plays the role of Cheeta.
    I have been cut, scraped, grazed, punctured, frozen, and soaked in muddy water while out in flood-waters more times than I can count. Heck, even the regular waterways were often as nasty as flood-waters. After reading the list in the blog entry above, a person might think I should have been, ‘rubbed-out’ long ago.

    I think the reason I didn’t get, ‘rubbed-out’ like Andy Holmes, the British Olympic rower, is because my immune system was very good. I credit: the type of food I ate, the sunshine I received, and God. Not too mention, I didn’t get all the vaxxcine shots people get nowadays.
    As Free Range kids, frequently when we were outside and got hungry we would go to a garden owned by one of our parents (we tried not to steal) often pulling a carrot from out of the ground, brushing off most of the dirt – but not all – and then eat the carrot as we went off to play some more. Thank goodness my parents had sense enough and were lucky enough to have a big garden to put food on the table, and apple and pear trees were everywhere, a nuisance even.

    That’s not to say I didn’t get my fair share of disgusting, ‘Wonder Bread’ and the like, however; my city friends who didn’t frequently eat from a garden or eat local wild caught fish regularly seemed to get sick all the time, while my fellow Free Range river rats and I seemed to get sick far far less often and to a lessor degree than the city-stay-inside and ‘Helicopter Mom’ kids did.

    IMHO, while it’s good to know about the above list of dangers found in water, and to be wary of those things, and it might be good to cover cuts and scrapes, wear waterproof gloves and thick soled boots, long trousers, and squeeze the cut to force as much contamination as possible out of the wound, etc… (more often than not, I never did those things) the higher priority is to build up and maintain your immune system, especially when you’re stressed.

    Please consider the following, ‘box outside the think’ links:

    Louis Pasteur vs. Antoine Bechamp: Know the True Causes of Disease

    ‘Mainstream medicine believes that virtually all illness is caused by germs or genetic hereditary weakness, as well as deformities and trauma injuries. Their solution and strategy is to have us believe that there are over 10,000 different diseases and that each of these diseases requires outside intervention from drugs and surgery. The truth is that most illness is due to cellular malfunction caused by cellular toxicities and cellular malnutrition, both of which can be avoided and overcome naturally’ …


    Louis Pasteur Vs Antoine Béchamp and The Germ Theory of Disease Causation – 1

    “In the sciences, people quickly come to regard as their own personal property that which they have learned and had passed on to them at the universities and academies. If someone else comes along with new ideas that contradict the Credo and in fact even threaten to overturn it, then all passions are raised against this threat and no method is left untried to suppress it. People resist it in every way possible: pretending not to have heard about it; speaking disparagingly of it, as if it were not even worth the effort of looking into the matter. And so a new truth can have a long wait before finally being accepted.”–Goethe

    ”… ignorance and power can be a dangerous combination. We do not catch diseases. We build them. […] The presence of germs does not constitute the presence of a disease. […] They are not the cause of the disease, any more than flies and maggots cause garbage.’ …


    Got Allergies? Here’s How Dishwashers Can Hurt You and Peanuts Can Help You

    ‘… There’s a tendency in our modern culture to be obsessive about cleanliness, especially in children. But the evidence is growing that a little dirt is good for you and probably even essential to keeping your body in sound working order.’ …


    Should We Eat Dirt?

    ‘… His latest experiment, the health effects of which he raved about, was adding dirt to his diet. I listened with interest and asked questions.’ …


    The Neglected Mineral We Cannot Live Without

    ‘Even though organically raised crops should be a better bet nutritionally, this isn’t always the case, and it pays in terms of your health to learn how your farmer replenishes the minerals on his fields.’ …


    Importance of Magnesium Is Far Greater Than Previously Imagined

    ‘Balance Your Magnesium with Calcium, Vitamin K2 and D’ …


    How To Prevent Sudden Cardiac Death: Cholesterol Pills Won’t Do

    ‘Sudden-death heart attacks often occur while exercising and sweating away important electrolyte minerals, particularly magnesium. According to a study by the National Collegiate Athletic Association, there is one SCA death per 22,903 athlete participant years among students 17-24 years of age [!!!] participating in NCAA sports.’ …


    Guide to Superfoods

    ‘The following short list is not meant to be exhaustive but only to provide a few examples of superfoods that can, in general, be taken by everyone.’ …


    Forewarned, is forearmed, eh?

    As far as snakes go, they sure do get aggressive and fearless when they are hungry. Surprisingly so. The two best tools I ever had for dealing with snakes was either a simple garden hoe – chop! – or a long stick with a Y-fork at the end to pin them down or fling them away.

    While walking through areas with snakes, if you can, walk slowly and stomp your feet as you walk, or take a stick and slap the ground or the surface of water covered grass as you walk, in my experience, that usually scares them off. And, always try to stand back a little as you lift things such as boards or tires from up off the ground, maybe lift it a bit, then let it plop back down a time or two before you fully lift it. Snakes usually go the opposite direction or off to the side after whatever you’re lifting plops back down on the ground. With something like a sheet of plywood I suspect might have danger underneath, I almost always lift from a corner, drop it, and then move to the front as I am lifting it the second time from the corner and then grab the center to finish the lift.

    In spite of all that (C’est la vie) act as if you expect a snake or a real rat to spring out, that way you won’t be surprised and panic when one does spring out in your direction. And (especially in flood conditions) try not to reach down into darkened areas where you cannot see well and then try to pick up things, even something as seemingly harmless as say, an empty flower pot. Even the best of us can forget something so simple like that in the heat of the moment while trying hard to get things done.
    F.y.i. if it feels cornered or a need to go with the flow, a real rat Will try and climb up your arm. Don’t ask me how I know. So, pay attention.

    With large logs, I would kick it first – hard – before attempting to move it. That is what has worked for me in the past. YMMV.

    Also, I would not try to poison all the snakes in an area, the non-poisonous ones can be very beneficial to have around. Even the poisonous ones can be beneficial, but I can understand why people would want to, ‘rub them out’.

    [Originally, I was going to post a portion of something like this comment in support of the choice to drink raw milk (can you see the connection?) on what turned out to be an anti-raw milk thread on another Prepper blog, …I give up on that bunch. They love their masters, too much. (Goethe) Anyway, i hope some people – especially the freedomista types here – find my, ‘too personally revealing and too long of a comment’ useful and worthwhile. …Even, david.]

    • Helot, very interesting comment, thanks. Are not vaccines supposed to introduce small amounts of dead germs/viruses into our bodies to help us build immunity? While you and your buddy river rats were growing up I would guess your exposure to all those friendly germs strengthened your bodies and you were able to fight off illnesses.

      I am not an expert in diseases, germs or infections, but me thinks that anything or any person that is pure could easily be contaminated by all of the above. I have read when explorers found natives in isolated areas, the natives soon got sick from the stuff the explorers were carrying; and visa versa; the explores got sick from what the natives shared with them.

    • Boy do I appreciate you taking the time to post your experiences from living life! Good thoughts all the way around and I learned a few things too!
      The links are great and Weston A Price is priceless for traditional wisdom regarding nutrition.
      I too grew up roaming the woods but no rivers and ate my share of dirt. My immune system is pretty healthy and I have been a raw milk drinker for the past 10 years or better. Gotta know your farmer!!
      Take care of yourself and keep sharing 🙂

  • hmm, helot, what a super comment, But… fyi, A ‘leptospirosis in dairy cattle’ search: About 54,000 results …’Leptospirosis is known to be a common disease of cattle generally resulting in reproductive failure such … be much lower in beef herds than dairy herds…’ seems raw milk consumption endorsed by WAPFoundation may not be a such a good idea.

    • Properly handled raw milk is safer than pasteurized milk. Raw milk will culture on its own, still be drinkable, useable and actually teaming with good bacteria as long as it hasn’t been contaminated.
      It will make cheese on its own also, but pasteurized old milk will ruin and needs to be discarded.
      Cheese can’t even be make from pasteurized milk with adding a liquid calcium. Ultra pasteurized milk can’t even be use at all for cheese making. Because it is a dead food!
      There is no evidence of any illness from properly handed raw milk!
      Be informed before you post Big Dairy’s views as truth, they fight to eliminate the family’s goat or cow.
      It all propaganda.
      End of rant.

  • Good advices. Mainly for the hazards of running water and hidden waste. I should add mold hazards. Mold overwhelms everything in flooded basements and houses, is difficult to get rid of, and, worse, is a major health hazard. As in New Orleans flooded houses (cleaning and ripping the soiled rooms was a huge work, and required a lot of protective gear). Please keep going on your blog !
    Anita – RN nurse.

  • Coming back to this page, updated Sept. 2021. Good advices. Mainly for major flooding, and worse in urban/tropical/subtropical areas. People who have to go (and even dive) in contaminated waters don “drysuits”, which covers everything tightly sealed (even around the face, most time protected by a mask or respirator). Good to know, and even for preppers, to get.

  • Grew up in South Florida. I have been in more hurricanes than I can remember. All of these are true, also here you have to watch out for gators, and I remember sharks being swept up in storm surges and ending up in people’s pools. Bugs will also swarm, you don’t want to get bitten by 100 fire ants either.

  • What happened to Lizzie? Did she go underground? Her link is dead, as is her Facebook and Instagram.

    Ok…I see… this is a 5 year old reprint.

    • Unfortunately, her website closed a few years back. The information is relevant with so many people dealing with floods, so I bumped it up to the front. Why are you so critical?

  • I’ll say the obvious: if you live in an area that’s likely to flood, your best bet is to try to move away from any area that may suffer flooding.

    • Doly,

      I’ve been wondering the exact same thing. It’s like someone complaining of a headache when they are banging their head repeatedly against a wall. MOVE!!!

      • Do you guys not understand that moving isn’t necessarily that easy? There are numerous reasons a person might not be able to pick up and move. Should one give up a good job when good jobs are hard to come by? What if you are upsidedown in your mortgage? What if your spouse doesn’t want to leave? What if you require specialist medical care and are established with a practitioner? What if your children require special services at school? What if you care for older family members who refuse to relocate? What if you just plain can’t afford it?

        These 5-second solutions for difficult problems are belittling and not helpful. There is no place in the world that is completely free of natural disasters. Add to this the potential of manmade disasters (remember the Oroville Dam?) and you’ll realize that the solutions are not always as simple as we can make it in a comments section.

  • You Need More Than Food to Survive

    In the event of a long-term disaster, there are non-food essentials that can be vital to your survival and well-being. Make certain you have these 50 non-food stockpile essentials. Sign up for your FREE report and get prepared.

    We respect your privacy.
    Malcare WordPress Security