A typical scenario: the som tam stall that had to close overnight

On the banks of the Mun River in Ubon Ratchathani, Aunt Daeng, 58, has run a small som tam and grilled chicken stall on the ground floor of her house for more than ten years. Her regulars are neighbours, factory workers and students from the nearby school. When the Mun burst its banks and flooded the community for nearly two weeks, her kitchen sat under brown water that had flowed through drains, septic pits and a neighbour's animal pens.

As soon as the water went down, she and her son scrubbed the stainless-steel tables, rinsed the clay mortar and the wooden chopping boards, and refilled the big water jar they used for washing vegetables and dishes. The water in the jar still looked a little cloudy, but she assumed it would settle. The ice cooler that had floated off during the flood was rinsed with plain water and put back into service. She wanted to reopen as fast as possible; two weeks without income had left the family with almost nothing to live on.

Three days after reopening, her four-year-old granddaughter, who ate sticky rice and grilled chicken at the stall every evening, began passing pale, watery stools from three in the morning and could not stop. Within a few hours the little girl had sunken eyes and a dry mouth and was becoming drowsy. The family rushed her to hospital, where she was immediately put on an intravenous drip. The doctor sent a stool sample for testing and explained that symptoms like these call for surveillance of food- and waterborne disease, including cholera, which must be reported to public health authorities. A few days later, district health officers inspected the stall and advised a temporary closure until the water supply and kitchen hygiene were fixed.

Fortunately the girl was treated in time and recovered. But Aunt Daeng told herself, "If I had known what the flood brought with it, I would never have rushed to reopen like that." This article explains what cholera and Vibrio bacteria are, how they get into a home, and how to restore a kitchen and living space safely.

This story is an illustrative scenario based on situations commonly seen after floods, not the account of a specific customer.

What are cholera and Vibrio bacteria?

Vibrio bacteria are curved, comma-shaped rods that thrive in water, particularly brackish water and water rich in organic matter. There are many species, but three matter most for households in Thailand after a flood.

Vibrio cholerae: the cause of cholera

Cholera is caused by toxin-producing strains of Vibrio cholerae. Once the bacteria reach the small intestine, their toxin makes the gut wall pour out huge amounts of water and salts. The result is profuse watery diarrhoea that looks pale and cloudy, often described as rice-water stool, usually without much cramping and sometimes with vomiting. In severe cases fluid loss is so rapid that a person can go into shock within hours. The incubation period is short, from a few hours to around five days.

A key point that the World Health Organization repeatedly stresses is that many infected people have no symptoms or only mild ones, yet still shed the bacteria in their stool for a period of time. Such people can unknowingly carry the infection into water supplies and food. The good news is that cholera responds extremely well to prompt rehydration, with oral rehydration salts and, where a doctor decides it is needed, intravenous fluids.

Vibrio parahaemolyticus: seafood poisoning

This species is usually linked to raw or undercooked seafood such as shellfish, prawns, pickled crab and spicy seafood salads. It causes abdominal pain, diarrhoea, nausea, vomiting and sometimes fever. The risk rises sharply after floods: refrigerators lose power, fresh food spoils quickly, and chopping boards or containers that touched floodwater become sources of cross-contamination. Stalls and restaurants that serve raw or lightly cooked dishes need to be especially careful.

Vibrio vulnificus: the wound threat

Near the coast or where floodwater mixes with brackish water, this species can enter the body through wounds exposed to water. It can cause severe skin infection with redness, swelling and intense pain, and may spread into the bloodstream, particularly in people with liver disease, diabetes or weak immunity. Anyone with a cut who has to wade through water should cover it well, and a wound that becomes red and swollen quickly needs a doctor straight away.

How the bacteria travel from floodwater to your mouth

• Contaminated household water. Jars, storage tanks and shallow wells that floodwater flowed into become a source of bacteria used for washing vegetables, rinsing dishes and sometimes drinking.
• Ice and ice containers. A cooler or ice bucket that was submerged and poorly cleaned delivers bacteria straight into drinks.
• Kitchen surfaces. Chopping boards, mortars, counters and dish racks that touched floodwater carry a thin film of silt that shelters bacteria.
• The cook's hands. Someone infected without symptoms who does not wash properly after using the toilet can pass bacteria to food that is not cooked again, such as som tam, fresh vegetables and dipping sauces.
• Toilets and drainage. Septic pits that overflowed during the flood leave faecal residue on floors, walls and pipes.

Who is at risk, and the danger signs

Young children, older adults, pregnant women, people with chronic illness or weak immunity, and people who regularly take antacids, which reduce stomach acid, are all at greater risk of severe illness. Go to hospital immediately if there are many large, watery stools, vomiting so bad that fluids cannot be kept down, very little urine, sunken eyes, wrinkled or slack skin, a weak rapid pulse, fainting or drowsiness. Do not wait and watch at home, because dehydration from cholera progresses very fast. Anyone who has waded through floodwater and then develops high fever with calf pain should also tell the doctor, because of the risk of leptospirosis.

The consequences go far beyond diarrhoea

The whole family's health

Severe dehydration can cause acute kidney injury and dangerous salt imbalances, and can be fatal if treatment comes too late. Even after recovery the body stays weak for days, while everyone else who used the same water and food remains at risk.

Money and income

For households that sell food, a single week of closure means losing all income, on top of medical bills, replacing chopping boards and utensils, cleaning water tanks and throwing away stock. All of this lands at the same time as flood repair costs.

Time and recovery

Once someone falls ill, recovery has to start again: water sources checked, the kitchen cleaned again, inspections awaited. The time lost is many times greater than the time it would have taken to do things properly in the first place.

Reputation and trust

In a small community, the rumour that "someone got diarrhoea after eating there" spreads faster than any germ. Loyal customers of many years may stay away even after the stall is spotless again. Within the family, the guilt of having made a child sick is a burden as heavy as any financial loss.

Why a rushed kitchen clean-up is not enough

Vibrio bacteria are not especially tough. They are fairly sensitive to drying and to chlorine. The problem is not that the germ is strong but that recovery steps are skipped, leaving the bacteria in exactly the conditions they like.

1. Washing with contaminated water. Using water from a jar or tank that floodwater flowed into to rinse chopping boards and plates simply coats freshly washed surfaces with new bacteria.
2. Scrubbing without disinfecting. Dish soap removes grease and silt, but without a proper disinfection step, bacteria lodged in knife scratches on a board or in the pores of a clay mortar remain.
3. Guessing bleach strength. Chlorine solution that is too strong damages utensils and leaves an odour; too weak and it does not work. Pouring it on and rinsing it off immediately, without contact time, sharply reduces its effect.
4. Forgetting non-cooking areas. Lower kitchen walls, under the sink, behind the fridge, table legs, storage shelves and the pantry floor were all under water but are often overlooked.
5. Shutting the kitchen up. A kitchen closed tight against dust or theft stays humid, organic residue never dries, bacteria survive longer and mould soon follows.
6. Masking drain smells with perfume or incense. Odours from drains and septic pits signal that waste is still present. Covering the smell hides the warning.
7. Painting or sheeting over damp walls. Covering walls that are still wet and have not been disinfected traps moisture, bacteria and mould spores underneath.

Washing with clean water, scrubbing off residue, disinfecting food-contact surfaces as recommended and drying everything thoroughly remain the heart of kitchen recovery. But kitchens and living spaces have many corners that brushes and cloths cannot reach, plus stale, humid air. That is where ozone treatment comes in to finish the job.

The answer: WHD residential and building ozone disinfection

World Health Disinfection (WHD) provides residential and building ozone disinfection for homes, home-based food businesses, condominiums, hotels, offices, factories, schools and hospitals. Ozone (O3) is a strongly oxidising gas that breaks down the cell structures of bacteria, viruses and mould, and splits apart the molecules behind musty odours. It then reverts to oxygen (O2) with no chemical residue, which makes it well suited to spaces where food is prepared.

According to test results the company has had certified by Thailand's Department of Medical Sciences and Intertek (UK), WHD's ozone process eliminates 99.99% of viruses, bacteria and mould. The advantage of a gas is that it reaches under the sink, behind the fridge, inside drawers, along shelving and into gaps between furniture: the very places floodwater flowed through but hand scrubbing cannot cover evenly.

One thing must be absolutely clear: ozone treatment of a room is not drinking-water treatment. Jars, tanks and wells must be drained, scrubbed and disinfected according to guidance from the Department of Health or local health officers before they are used again. And ozone is only carried out after mud removal, washing and drying are complete.

How the process works

1. Survey and history. The team checks how high the water rose, where the kitchen, pantry, bathroom and water sources are, and whether anyone in the household has had diarrhoea, so the zones can be prioritised.
2. Readiness check. They confirm that mud is out, utensils are washed, surfaces are dry and all food and ingredients have been removed. Cupboards and drawers are opened so the gas can reach inside, then doors and windows are closed to seal the space.
3. Empty space. People, pets and plants must leave the treatment zone entirely, without exception.
4. Ozone treatment with contact time. Professional ozone generators are used, typically for about 30 minutes per zone, adjusted to the size of the area.
5. Rest and ventilation. The ozone is allowed to break down into oxygen, then doors and windows are opened to air the space. People are allowed back in only at the time the team specifies.
6. Aftercare advice. The team advises on separating clean and dirty zones in the kitchen, looking after high-touch points, and keeping water sources safe going forward.

10 reasons flooded homes and food stalls choose ozone

1. No residue in food areas. Ozone becomes oxygen after it reacts, leaving no chemical smell or film on kitchen surfaces.
2. It reaches every gap the water passed through. Under the sink, behind the fridge, beneath shelves and inside drawers are all treated at the same time.
3. It clears drain and damp odours. Ozone breaks odour molecules at the source, so the kitchen air is genuinely clean rather than perfumed.
4. Confidence before you reopen. A home-based food business can tell customers the premises were disinfected by professionals. See the ozone disinfection service for details.
5. Backed by test results. Company test results certified by the Department of Medical Sciences and Intertek show 99.99% elimination of viruses, bacteria and mould.
6. Minimal downtime. About 30 minutes per zone plus rest time, so a typical home or small shop is done in a day.
7. Safety managed by the team. People, pets and plants are cleared, the area is sealed and a clear re-entry time is given.
8. It curbs post-flood mould. Damp kitchens and storerooms often grow mould, so one treatment tackles several problems. Read more on the residential ozone service page.
9. The whole house, not just the kitchen. A bathroom where the septic pit overflowed, bedrooms and the living room can all be treated zone by zone.
10. A bonus you will actually use. Ozone jobs of 15,000 baht or more include a free medical-grade disinfectant spray for tables, counters and high-touch points after reopening.

Before and after ozone treatment

Example case: getting a home-front som tam stall safely back in business

Note: this example case is compiled from common post-flood situations to illustrate the sequence of steps. It is not a review from any real customer.

After her granddaughter recovered, Aunt Daeng decided to stay closed for one more week and do everything properly. The first step was water. Her son drained the jar and storage tank completely, scrubbed out the sediment and disinfected them according to the health officers' advice. In the meantime the family used bottled water for drinking and cooking.

Next, she threw away the deeply cracked wooden chopping board and the clay mortar that had been submerged, because porous materials are very hard to clean thoroughly. She switched to colour-coded plastic boards for raw and cooked food and bought a new ice cooler. The stainless tables, dish racks and kitchen floor were scrubbed with detergent and clean water, food-contact surfaces were disinfected as recommended, and the kitchen was left open to the breeze until it was completely dry.

Then the WHD team surveyed the premises and divided them into three zones: the kitchen and front selling area, the back storeroom, and the bathroom where the septic pit had overflowed. Ingredients, rice and seasonings were moved to a relative's house; the backyard chickens and pots of chillies were moved well away. Every cupboard and drawer was opened, the team sealed the rooms, treated one zone at a time for about 30 minutes, then rested and ventilated the space before telling the family they could return.

Aunt Daeng noticed that the drain smell that used to rise every evening was clearly gone, and the corner under the sink no longer smelled stale. When she reopened, she put up a small sign telling customers that the water supply had been fixed and the premises disinfected after the flood, and placed a hand-washing basin with soap at the front. Her regulars gradually came back. Results always depend on the premises, the cleaning done before treatment and ongoing hygiene.

Post-flood kitchen and home recovery checklist

Drinking and household water

• Drink boiled water or sealed bottled water until local authorities confirm tap water is safe.
• Drain jars and tanks that floodwater entered, scrub them and disinfect them following Department of Health guidance before reuse.
• Discard ice of unknown origin, and replace or disinfect ice containers that were submerged.

Food and utensils

• Throw away all food that touched floodwater, and fresh food from fridges that lost power for a long time.
• Discard wooden boards, clay mortars and porous containers that were submerged; wash and disinfect metal and glass items before use.
• Cook food thoroughly, especially seafood, and avoid raw or lightly cooked dishes in the weeks after a flood.
• Keep separate boards and knives for raw and cooked food.

Before ozone day

• Remove mud and wash all surfaces with clean water and detergent, wearing gloves, boots and a mask.
• Dry the building within 24 to 48 hours, as WHO and CDC advise.
• Take food, ingredients and seasonings out of the treatment area.
• Arrange temporary places for people, pets and plants.

After ozone

• Re-enter only after the rest and ventilation period set by the team.
• Wash hands with soap after the toilet and before preparing food; anyone with diarrhoea should not cook for others.
• Wipe tables, counters and high-touch points daily.
• If anyone develops watery diarrhoea, see a doctor at once and mention the flood exposure.

Frequently asked questions

1. After ozone treatment, can I use the water in my jar?

No. Room ozone treats air and surfaces; it does not treat water. Jars and tanks must be drained, scrubbed and disinfected according to public health guidance before reuse.

2. Will ozone leave residue on food in a restaurant kitchen?

All food and ingredients are removed before treatment. Ozone breaks down into oxygen after reacting, so it leaves no chemical residue on kitchen surfaces.

3. Can we stay in the shop or house during treatment?

No. Ozone treatment is done only in an empty, closed space. People, pets and plants must leave, and may return after the rest and ventilation period the team specifies.

4. Does ozone prevent cholera 100%?

No single measure prevents everything. Cholera spreads mainly through drinking water and food, so protection needs several layers: safe water, thoroughly cooked food, hand washing and a clean kitchen. Ozone is an extra layer that deals with germs on surfaces and in the air of the space.

5. What should we do if someone has watery diarrhoea?

Start oral rehydration salts immediately and get to a doctor quickly, especially for young children and older people, because dehydration can become severe within hours. Ozone is not a treatment for illness.

6. How long does treatment take?

Typically about 30 minutes per zone, not counting preparation and rest time. The team confirms the exact timing after the survey.

7. Is there a promotion?

Ozone jobs of 15,000 baht or more include a free medical-grade disinfectant spray. Ask by phone or LINE.

A clean kitchen and a safe home before life restarts

Once washing and drying are done, let WHD finish the job with ozone disinfection that covers every corner of your kitchen and home.

Book Post-Flood Ozone Disinfection

Call 065-556-6294 · LINE @whd268 · worldhealthdisinfection@gmail.com

Related services

• Residential and building ozone disinfection
• Ozone and chemical residue reduction
• Full disinfection service
• Test certificates

References

• World Health Organization: fact sheets on cholera and safe drinking water
• CDC: Floods – food, water and cleanup safety