How to Protect Yourself from Flood Borne Illness: Harvey and Irma Edition

Jodie Weston Jodie Weston  |  Updated: September 10, 2020
How to Protect Yourself from Flood Borne Illness: Harvey and Irma Edition

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It’s time to brush up your flood survival knowledge. The latest media reports about Hurricane Harvey reveal that at least 50+ people have died while 32,000 people are in official shelters. The cost in life is a tragedy, especially to preppers who often wonder how these lives could have been saved.

Yet, the effects of Hurricane Harvey (and now Irma) are far from over. For all those in the area, the high flood waters present a danger, especially in terms of the illness it can spread. We’ll outline how you can prevent contracting an illness from flood water.

This will be helpful whether you’re stuck in the midst of an ongoing disaster area, or whether the disaster has just served as your reminder to brush up on your hurricane and flood survival plan. We’ve listed the potential dangers from most likely to least likely, and there’s a quick summary of the general best practices you should follow at the end of the article.

Bacterial and Viral Infections

As floodwater sweeps through streets it overburdens sewage systems, freeing all kinds of nasty bacteria and viruses. The water provides convenient transport for the freed illnesses which can’t travel through the air, making everything the flood water touches potentially infected.

Unfortunately, after-flood illnesses are very common because they spread so easily and many people aren’t aware of the precautions they need to take to protect themselves.

The Guardian spoke to a doctor, Rick Watkins, who researched flood-borne diseases after Katrina. He advised that after Hurricane Harvey, “The main thing that people have to watch out for is gastrointestinal infections.” These spread easily, and are the last thing a stressed hurricane survivor needs to deal with right now.

To prevent exposing yourself to these illnesses, you should not eat any food that flood water may have touched, and you should try to prevent your skin from directly contacting the flood water whenever possible.

As you clean your home, you should wipe down surfaces which have touched flood water with a bleach solution. When bleach is not available, washing surfaces down with soap and hot, clean water are the next best option.

It’s also important to recognize when you may have contracted an illness, and because some of these illnesses are usually quite rare, it’s a good idea to brush up on their symptoms and treatments.

Escherichia coli (E-coli), Shigella, Norovirus, Listeria and other gastrointestinal illness

Theses beasties will be the primary danger floating around in flood water. All can cause vomiting, diarrhea, stomach pain, and other classic food poisoning symptoms. If you get sick with one these illnesses you need to stay hydrated, re-double your sterilization efforts, and make sure your waste is being disposed of properly.

Most people will be uncomfortable, but will recover from these illnesses in three to seven days. But, you also need to be on the look-out for signs that your gastrointestinal illness needs medical attention. According to St. John Ambulance, you should seek medical attention if you have any of these symptoms:

  • You suffer consistent or recurring vomiting and diarrhea for more than three days
  • You have a persistent fever
  • Your stomach pain or cramping is excruciating
  • You have excessive thirst, a dry mouth, or dark urine
  • You are confused, have blurred vision, muscle weakness, feel tingling, or suffer paralysis

The health department in Texas, according to Newsweek, has stocked up on the medications needed to combat these illnesses, and is prepared to deal with cases in shelters and among people who have been able to return to their homes. But, look up your local clinic or hospital before you go, many have been evacuated or are temporarily closed.

Rarer Illnesses

Hepatitis A, hepatitis E, cholera, and other diseases may be spread by flood water, but because of advanced sanitary conditions in the USA, an outbreak of these diseases is very unlikely. A person infected with cholera would have to travel to Texas to infect the floodwater, which is highly unlikely.

Hepatitis A and Hepatitis E can transfer through water (specifically if the fecal matter from an infected person pollutes the water and then you drink that water) but boiling your water takes care of this issue. As long as you are practising proper sanitation you are fine.

Protecting your water from viruses and bacteria

There are currently reports that all tap water in Houston is now safe to drink, while in other areas it is not. You’ll need to google your area to find out if your water treatment plants have been effected.

After that, check the sewage and waterlines in your own home for damage. You should inspect your utilities for damage in general, and you can find out how to do so here.

If your water is not safe you should boil it for ten minutes, or use a filter which targets bacteria and viruses like the Katadyn pocket, or see more options in our guide here.

Katadyn Pocket Water Filter

At higher elevations you may have to boil for longer, but I’m relatively certain no one in Texas is more than 1000 feet above sea-level. It’s just something to know for future disasters. You can find out more about water purification here.

It can be very frustrating to try to function without running water, so consider reading our 16 tips fpr coping with the situation.

Protecting your food from viruses and bacteria

Do not eat food which may have been exposed to flood water, even if it doesn’t look like it necessarily was. Food in your cupboards could have been sprayed with contaminated water, even if it didn’t soak. Food in water-proof containers should be fine, as long as the container was not submerged and/or did not leak.

Keep what safe food you have in a waterproof container— after first sterilizing that container with a bleach solution. This way you’ll also protect the food from mold growth, which is likely after floods. If you are storing raw meats, keep them in their own sterilized and water-proof container.

Always wash your hands with soap and warm water before eating. Take extra care when washing dishes.

Injuries in Floodwater

When unsanitary floodwater is everywhere, it is particularly dangerous to have broken skin, from a simple splinter, a small burn, or an insect bite, to something as serious as a puncture wound.

It’s also more likely that you’ll get a cut during a flood, as the water may be carrying glass shards and metal hazards. Be careful when wading through water, and remove floating shards from your home as soon as possible.

Your risk for infection is higher when you get a cut in flood water. So:

  1. Clean your cut immediately with warm water and soap or, if clean water is in short supply, use rubbing alcohol (isopropyl alcohol).
  2. Bandage the cut properly and do not let it touch flood water. This means not allowing the bandage to soak, and ideally protecting the cut area with water-proof clothing.

We suggest you buy this book for future survival medical needs, the Survival Medicine Handbook (now in its third edition).

The Survival Medicine Handbook by Joseph Alton MD


You’ll hear the widespread advice that you need a tetanus shot if you’ve been caught in a flood. But, according to the CDC, contact with floodwater does not increase your chances of contracting tetanus.

Various medical experts confirmed the CDC’s position to Stat News. If you have a puncture wound from a nail or other metal object, then you need a tetanus shot. If you just got a simple cut while in the midst of a flood, tetanus is not a worry.

The experts on Stat News warned that calls for everyone to get their tetanus shot will overwhelm clinics and hospitals, which are already feeling the toll of the hurricane.

The best thing to do if you realize you’re behind on your tetanus shot (and haven’t gotten a puncture wound), is to wait until clinics and hospitals are running normally, and then get your tetanus shot for next time.

The myth that you need a tetanus shot when in flood water probably came inadvertently from clean-up crew organizers. Cleaning up after a flood does make it more likely you’ll suffer a puncture wound, so organizers want to make sure that volunteers have had a tetanus shot in the last 10 years.

The CDC doesn’t think having documentation of your tetanus shot should be required to volunteer, but it is good to have. When word got out that organizers wanted you to have your shot to volunteer, people may have thought flood water was the reason, not just your higher likelihood to be hurt.

All this being said, as just an average flood survivor, you are more likely to expose yourself to tetanus the usual way than you normally would be. If you do get a puncture wound and it has been more than 10 years since your last tetanus shot, you do need the shot.

Symptoms of tetanus usually don’t appear for seven to ten days after you were exposed to the bacteria which causes it (Clostridium tetani). But, you should seek the shot immediately after caring for your wound. According to the Mayo Clinic, once symptoms do arrive they are:

  • sore jaw muscles that spasm
  • stiff neck muscles
  • difficulty swallowing
  • stiff stomach muscles
  • painful muscle spasms that last a minute or more and are triggered by simple things like touch, a small breeze, or a startling noise

If you experience these symptoms, it’s imperative you seek medical attention right away, from a hospital if you can get to one.

Remember that tetanus is often fatal.

It’s likely tetanus will also cause fever, sweating, high blood pressure and high heart rate as well, but without the muscle stiffness these symptoms could also be other illness and infections. When in doubt, see a doctor.

Mosquito Borne Illnesses

In the immediate aftermath of a flood, mosquito populations actually dwindle. The adults need stagnant water to breed in, and flood water is moving. But, once floodwater recede, mosquito populations will recover in the many small pools of water leftover.

It could be days until the floodwaters from Hurricane Harvey recede, or it could be weeks.

According to Peter Hotez, an expert in tropical medicine working out of Texas’ Baylor College of Medicine, if the flood recedes quickly the mosquitoes may begin breeding again before their season is over, causing a bump in their population this year. If the flood doesn’t recede until their season is over, mosquitoes will benefit from the flood next year.

Whenever they arrive, these extra mosquitoes will mostly be annoying. However, some will carry disease. Once the floodwater has receded:

  • Take some time to dump out anything containing water around your house.
  • Replace glass and screens on your home as soon as you can, and try to spend your time indoors when possible.
  • Wear light-colored long sleeved shirts and pants when outdoors.
  • Stock up on bug spray, or remember to stock up before the problem begins next year (hopefully buy before the price of the spray goes up). Also, for next time, put bug spray in your bug-out bag.

West Nile

As the Atlantic notes, immediately after Hurricane Katrina, there was no change in West Nile rates. But, the following year mosquitoes took advantage of the extra breeding spots and spread twice as much West Nile neuroinvasive disease, a serious variant of West Nile, as was otherwise expected.

While this type of West Nile is severe, it is rare, and death from it is also unlikely. For example, there were 27 cases of West Nile neuroinvasive in Louisiana in 2016, and only one case was fatal.


The mosquito which carries Zika is called Aedes aegypti. Unlike the mosquito which carries West Nile, this mosquito prefers to breed in small bodies of water. Because floods make most bodies of water large, these guys a less of a concern than their cousins.

For example, according to the Department of Health, after the Louisiana flood of 2016, there were a few cases of Zika, but none were due to the flood. Everyone who contracted Zika brought it home from visits abroad to infected area. all cases were This means that not a single case was caused by mosquitoes who bred in the flood.

On the other hand, there has already been domestic transmission of Zika in Texas this year, according to the New York Times, in Hidalgo County. If you live nearby, be extra sure to protect yourself from mosquitoes.


Though it is much more of a concern in third world countries, there is a record of Dengue fever in Houston. All of the recent cases have been imported, but there were domestic cases of dengue in 2003. This is an extraordinarily unlikely threat (if you haven’t travelled to an effected are) but if you want to be prepared for everything, it’s a good idea to know what dengue looks like.

Some people who are infected will not have any symptoms, most will have a high fever, headache, and vomiting. The tell tale sign is a rash that develops two to five days later. A few will contract a more serious version that causes bleeding.

There is no vaccine or cure, but supportive treatments can help, so if you suspect you or someone you know has this, head to the hospital.


A chemical plant exploded as a result of losing power from Hurricane Harvey. The company which runs the facility admitted they did not have another method to cool the chemicals, which would inevitably burn off. Everyone within a mile and a half of the plant was evacuated.

The EPA has since surveyed the smoke from the plant and has not found significant levels of any concerning toxin, but anyone who comes into contact with the smoke should still seek medical attention. It seems the chemicals have not leaked into the floodwaters, but I would keep my ears perked for future warnings about that.

The more general lesson here for preppers is to always be listening to breaking alerts from authorities. One disaster often leads to another.


Though some houses that were flooded are going to develop mold, it really is the least of your concern. Mold on your walls is generally harmless to most people. After all, we breathe in some degree of mold every day.

Some people have allergies to mold akin to seasonal allergies from plants. It can be uncomfortable, causing sneezing, a stuffy nose, a scratchy throat and even skin irritation, but this is highly unlikely to be life-threatening, unless it is making another condition you have worse.

There is some evidence that one mold, Stachybotrys, may have caused four deaths after Hurricane Katrina, but the science isn’t in on this issue. The four professors who died, and ten students who remain alive, suffered coughing and other respiratory issues. For five years, the professors taught on the floor with the mold, which was not removed. Then they all died within three months of one another. It is not certain if the mold killed them, compounded another issue, or had no effect. Many other people worked or studied on the floor without a problem.

That being said, if mold is making you feel ill, leave and get a professional to remove it thoroughly.

Best Practices

Here’s a quick summary of how to prevent illness in flood water:

  • Wash your hands frequently, especially before eating
  • Check to see if your area has a water boiling notice
  • Check your own home for water line damage, if so boil water or a use a filter which deals with microorganisms (like thee Katadyn pocket, or see more options in our guide here)
  • Remove standing water whenever possible
  • Limit your skin’s exposure to floodwater as much as possible
  • Do not submerge wounds in floodwater, and regularly clean wounds
  • Only get a tetanus vaccination if you have a puncture wound
  • Limit exposure to mosquitoes however possible, including with long clothing, staying indoors, and applying bug spray
  • Soon after the flood water recedes, empty any small pools of water you can find
  • If mold makes you feel ill, leave and have a professional clean it

Final Thoughts

There’s just so much to prepare for and deal with when it comes to floods. It’s not an illness, but another danger flood water brings in is snakes. In general, keep your eye out for snakes, do not approach them, and know how to identify the coral snakes, so you’ll know which of the two antivenoms used in the USA you’ll need. See our full guide on how to survive a snake bite here.

Also – keep in mind that power outages often occur after hurricanes, because of damage to the electrical grid. Incorporate this knowledge into your own survival plan for the next time.

Remind friends and family who aren’t preppers to do the same, because even if they avoided Hurricane Harvey and Irma, they may not avoid the next disaster.

Our thoughts and prayers go out to the victims, first responders, and volunteers dealing with Hurricane Harvey and Irma. Stay safe!

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One Response to “How to Protect Yourself from Flood Borne Illness: Harvey and Irma Edition”

  1. I live in Florida (hurricane Irma) but my area wasn’t affected by flood waters just high winds (causing mostly tree damge). Other parts of the state were affected by flooding and additional damge (tree, roof, vehicle & home) but nothing compared to hurricane Harvey.

    I keep my tetnaus up-to-date (every 10 years) but this last time the doctor gave me Tdap (“Tdap is a combination vaccine that protects against three potentially life-threatening bacterial diseases: tetanus, diphtheria, and pertussis (whooping cough).”

    This year my doctor gave me adult pneumonia vaccine (“provide protection against illnesses like meningitis and bacteremia. PCV13 also provides protection against pneumonia”). I hope the combination of these two vaccines will help.

    I noticed some of the rescuers (civilian & professional) during hurricane Harvey were wearing hip-waders. This should have helped but not everyone had access to hip-waders.

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