A typical scenario (an illustrative example, not a review from a specific customer)

A two-storey dormitory in Ongkharak and the students who moved out mid-semester

Wanna owns a two-storey dormitory with sixteen rooms in Ongkharak district, Nakhon Nayok. Most tenants are university students and local workers. After days of heavy rain, with extra water flowing down from upstream, the flood crept across the parking area and into all eight ground-floor rooms, reaching about mid-shin and staying for several days. Ground-floor tenants carried their belongings upstairs to friends' rooms. Some went home to their families in other provinces.

When the water receded, Wanna hired workers to shovel out the mud and wash the floors with bleach, then reopened the rooms within three days because she was worried about lost rent. Less than two weeks later, a tenant sent her a photo of grey-green mold growing along the edge of a wooden door and under a mattress. Another complained of a drain smell coming up through the bathroom floor every evening. Two students had diarrhea in the same week. In the end, two rooms gave notice and moved out in the middle of the semester.

None of this happened because Wanna failed to clean. It happened because the rooms were reopened before the walls, wooden doors and mattresses had fully dried, and because flood germs do not stay only on the floor that gets washed. They remain in the drains, the corners, the air and inside porous materials. This picture is common across Nakhon Nayok after the water goes down, whether in detached houses, shophouses, dormitories or resorts.

Nakhon Nayok flood 2026: four districts, 49,018 households, and water from Khun Dan Prakan Chon Dam

According to the DDPM report of 2 October 2026, flooding nationwide affected 31 provinces plus Bangkok, covering 1,245,581 households and 3,535,206 people. The cause was heavy to very heavy rainfall combined with large volumes of water from the North.

For Nakhon Nayok in the eastern region, the same DDPM report listed four affected districts: Pak Phli, Mueang Nakhon Nayok, Ban Na and Ongkharak, with 49,018 households in total. Thai PBS reported that Khun Dan Prakan Chon Dam was releasing water into Khlong Tha Dan and the Nakhon Nayok River. These figures reflect the situation on the day of reporting and may rise or fall daily, so residents should keep checking provincial and DDPM announcements.

Nakhon Nayok has mountains in its upper part that act as headwaters, with water draining down into a broad lowland plain. When runoff from the hills and dam releases meet heavy local rain, the main waterway, the Nakhon Nayok River, carries a large volume. Homes on the plain, such as in Ongkharak and Ban Na with their wide rice fields, as well as riverside communities in Mueang and Pak Phli, are more likely to see water enter and stay longer than homes on higher ground.

Housing in Nakhon Nayok is very varied: raised wooden houses in farming villages, single-storey concrete houses in housing estates, shophouses in town, dormitories for students and workers, and resorts and holiday homes for visitors who come for the waterfalls and nature. Each type has its own weak points when it comes to post-flood germs, as explained below.

Every kind of germ that floodwater brings into Nakhon Nayok homes

Water that has flowed across rice fields, animal pens, septic tanks and roads before reaching a house carries all sorts of contaminants. When it stands for several days, warm, still and full of organic matter, conditions become even better for germs to multiply.

Fecal bacteria: E. coli, Salmonella and relatives

When septic tanks and drains overflow, floodwater carries E. coli, Salmonella and Shigella from feces into the home. These bacteria cling to floors, lower walls, tables, kitchen cupboards and anything that was submerged. If cleaning is incomplete or contaminated dishes are used, the result can be diarrhea, vomiting, stomach pain and fever. In dormitories where tenants share bathrooms and rubbish points, person-to-person spread happens fast.

Leptospirosis: the risk for anyone who wades

Wide rice-growing areas like Ongkharak and Ban Na have many field rats. When floods come, rats flee to higher ground and into houses. Their urine carries Leptospira bacteria into the water and mud. The bacteria enter through wounds, scratches or skin softened by long soaking. The classic signs are sudden high fever, headache and severe calf pain, sometimes with red eyes and reduced urination. If these appear roughly one to two weeks after wading or cleaning, go to a hospital immediately and tell the doctor you were exposed to floodwater.

Viruses: norovirus, rotavirus and respiratory viruses

Norovirus and rotavirus spread through hands, food, drinking water and contaminated surfaces, causing severe vomiting and diarrhea, especially in children. While families crowd together at relatives' homes, in shelters or on the upper floor of a dormitory, respiratory viruses also spread easily. Conjunctivitis and skin infections from prolonged immersion are additional concerns.

Mold: the problem that appears days after the water leaves

WHO and CDC advise cleaning and drying a flooded home within 24 to 48 hours to limit mold. In reality, in homes where water stood for days as in parts of Nakhon Nayok, mold has often started growing before anyone can get in to clean. It typically appears on ground-floor plaster walls, gypsum ceilings, plywood doors, wardrobes, mattresses, curtains and rugs. Airborne spores cause blocked noses, sneezing, coughing, asthma attacks and eye and skin irritation.

Musty and drain odors

A musty, damp smell comes from mold and bacteria growing in materials that are still wet. A rotten or drain-like smell comes from mud and sediment left in pipes, under floors and inside wall cavities. Both are signs that microbes are still active. Cover them with perfume and they return as soon as it fades.

Groups who need extra care

Elderly people, young children, pregnant women, people with diabetes, kidney or heart disease, allergy and asthma sufferers, and anyone with weakened immunity. Dormitory owners in Ongkharak and Mueang must think about tenants living close together and sharing common areas. Resort owners must think about guests who check in without knowing a room's flood history.

The damage that follows when Nakhon Nayok homes skip recovery steps

Health: waves of illness in the household, diarrhea in children, flare-ups of allergies in older people, and leptospirosis risk for anyone who cleaned without protection.

Money: items that grow mold again have to be thrown away, walls and wooden doors must be replaced, and for dormitories and rental rooms, income disappears every day a room sits empty or a tenant leaves.

Time: scrubbing mold every week and repainting only to see it return can drag recovery out to the end of the year.

Reputation: a dormitory known for "smelly rooms" or a resort reviewed as "I woke up congested" loses trust quickly, both among students who share news fast and among travelers who read reviews before booking.

Family: the stress of living at a relative's home for weeks, the worry that children will fall ill, and the exhaustion of cleaning the same rooms repeatedly are burdens as heavy as the bills.

Why Nakhon Nayok homes still smell and grow mold after washing and spraying

Bleach alone. Bleach suits smooth surfaces like tiles and toilets but does not penetrate to the mold threads inside plaster, plywood and gypsum. Too strong a mix, or mixing it with other cleaners, creates dangerous fumes, so follow Department of Disease Control guidance.

Reopening rooms before they dry. This is the leading cause of mold regrowth in dorms and rentals. Once tenants return, switch on air conditioning, close the room and dry laundry indoors, moisture builds up even more.

Fans or air conditioning only. These lower humidity somewhat but kill nothing, and an air conditioner that was flooded or sits in a moldy room can spread spores.

Perfume and odor powders. They mask the smell for a while but leave the source untouched.

Painting over stains. Mold pushes back through within weeks and leads to bigger demolition later.

The shared limitation is that all of these reach only what you can see and touch, while flood germs live in the air, in corners and in porous surfaces. Ozone is the complementary step that treats the entire volume of a room after washing and drying.

WHD ozone disinfection in Nakhon Nayok: principles and process

World Health Disinfection (WHD) provides ozone disinfection for homes, condos, dormitories, hotels, offices, factories, schools and hospitals. WHD is based in Bang Khae, Bangkok 10160, and has no branch in Nakhon Nayok. The team can plan service in the province, with travel, coverage and timing confirmed by phone at 065-556-6294 or LINE @whd268 beforehand. Same-day arrival is not guaranteed.

Ozone (O3) is a gas with strong oxidizing power. When it contacts bacteria, viruses and mold spores, it breaks down their cell structures and outer envelopes, and it also breaks apart odor molecules. Afterwards it reverts to oxygen (O2), leaving no chemical residue. According to test results certified for the company by the Department of Medical Sciences and Intertek (UK), it eliminates viruses, bacteria and mold by 99.99%.

The key advantage for homes and dormitories in Nakhon Nayok is that ozone is a gas, so it reaches behind wardrobes, under beds, into ceiling corners and bathroom gaps that cloths and brushes cannot. Work can be done room by room or zone by zone, which suits dormitories that want to reopen rooms in stages.

Service steps

1. Consultation and assessment: send photos plus details of water height, flood duration and number of rooms on LINE. The team helps split the job into zones.
2. Clean and dry first: remove mud, discard damaged items, wash and ventilate until fully dry.
3. Clear the area: people, pets and plants leave every zone to be treated, and doors and windows are closed.
4. Fill and contact time: a typical cycle is about 30 minutes per zone.
5. Rest and ventilate: the ozone is allowed to break down, the room is aired, and only then is it reused.

Safety first: ozone treatment is carried out only in a closed, empty room. No people, pets or plants may be inside, and re-entry happens only after the rest and ventilation period the team specifies.

Further reading: ozone and chemical residue reduction and ozone disinfection machines.

10 reasons Nakhon Nayok residents choose ozone after the water recedes

1. Whole-room coverage, not just wiped spots. The gas fills the room, including air carrying spores.
2. Several germ groups at once. Bacteria, viruses and mold at 99.99% according to the company's certified tests. See the ozone disinfection service.
3. Helps with drain and musty odors. It breaks odor molecules down instead of masking them.
4. No residue. Suitable for children's rooms, elderly relatives' rooms and tenants' rooms.
5. Zone by zone. Dorms and resorts can reopen finished rooms first.
6. Short cycles. About 30 minutes per zone makes scheduling clear.
7. Less mold regrowth. When done after drying and followed by humidity control.
8. Restores tenant and guest confidence. Dorm owners in Ongkharak and resort owners in Mueang can tell customers rooms have been disinfected. More on the ozone service page.
9. Backed by test results. See the certificates page.
10. Good value for multi-room jobs. Ozone jobs of 15,000 baht or more come with a free medical-grade disinfectant spray.

Before and after: a flooded ground-floor room in Nakhon Nayok

Note: results depend on cleanliness and dryness before treatment. Rotten, swollen or deeply moldy materials should be replaced first.

Example case: a single-storey house beside the rice fields of Ban Na

An illustrative example to explain the process, not a real customer review.

Prayoon, a 60-year-old rice farmer, lives with his wife and his daughter, who is five months pregnant, in a low single-storey concrete house beside the fields in Ban Na district, Nakhon Nayok. Water from the fields rose to about shin height inside the house and stayed for several days. The family moved to a relative's house on higher ground.

When the water went down, Prayoon kept his daughter away from the house at first. He and his wife put on boots and gloves, removed the mud, threw out mattresses, pillows and seat cushions that had soaked, removed a swollen plywood wardrobe entirely, washed floors and walls with clean water and detergent, and opened every door and window with several fans running for nearly a week until walls and floors were dry. Even so, a musty smell remained in the bedrooms and bathroom.

Their son, who works in Bangkok, contacted the WHD team on LINE, sent photos and mentioned that his sister was pregnant. The team suggested three zones, two bedrooms plus the bathroom and kitchen, and agreed on a convenient date for travel to Nakhon Nayok. On treatment day the whole family stayed at the relative's house. The team treated one zone at a time and told the family when they could return after the rest and ventilation period.

The family noticed that the musty smell in the bedrooms was much weaker and the daughter felt more comfortable sleeping in her own room again. The team still stressed that she should keep attending prenatal checkups as normal, and that anyone in the house with fever, calf pain or diarrhea must see a doctor promptly. Ozone looks after the house. It does not replace medical care.

Extra notes for dormitory owners and resort operators in Nakhon Nayok

Reopen in stages, not all at once. Rather than reopening every ground-floor room on the same day, finish one block of rooms completely, from mud removal and washing through drying and ozone, and let tenants back into those first. This keeps some rent coming in while giving the remaining rooms the drying time they need.

Keep a simple room log. Note for each room how high the water rose, what was thrown away, when the walls were dry, and the date of disinfection. If a tenant or guest asks whether a room flooded, an honest, organized answer builds far more trust than silence.

Do not forget shared spaces. Laundry corners, shared bathrooms, stairwells, reception areas and storerooms often get less attention than private rooms, yet they are where most people pass through. Plan them as separate zones.

Check air conditioners and mattresses. An air conditioner that sat in a damp, moldy room should be cleaned by a technician before use. Mattresses that soaked in floodwater should be replaced, not just sun-dried.

Communicate clearly with tenants. Let them know when their room will be treated, that they must stay out during treatment and ventilation, and who to contact if they notice a smell or feel unwell afterward.

Nakhon Nayok recovery checklist for homes and dormitories

Before going back in

• Follow provincial and DDPM announcements, since dam releases and new rain can change water levels.
• Switch off power at the breaker and have an electrician check wiring, water pumps and any air conditioner that was submerged.
• Watch for snakes, venomous creatures and rats that fled into the house.
• Wear boots, rubber gloves and a mask, and cover all wounds.

Washing and drying

• Remove all mud from rooms, parking areas and drainage channels.
• Discard porous items that cannot be cleaned, such as mattresses, pillows, rugs and swollen plywood furniture.
• Wash floors, walls and sanitary ware with clean water and detergent, then disinfect surfaces per Department of Disease Control guidance.
• Flush floor drains and odor traps to reduce drain smells.
• Ventilate to dry as fast as possible, and do not rush to close rooms and switch on air conditioning.

Treatment day

• All people, pets and plants leave the zones being treated.
• Open cupboards and drawers, close doors and windows.
• Return only after the rest and ventilation period.

After ozone

• Ventilate daily, control humidity and avoid drying laundry indoors.
• Repair roof and wall leaks.
• Watch the health of family and tenants. Fever, calf pain, diarrhea or breathing problems mean see a doctor.

FAQ: ozone disinfection in Nakhon Nayok after flooding

1. Can WHD serve Ongkharak, Pak Phli and Ban Na?

WHD is based in Bang Khae, Bangkok, with no branch in Nakhon Nayok, but the team can plan service in the province. Travel and coverage are confirmed by phone at 065-556-6294 or LINE @whd268.

2. The water has not fully drained. Can we do ozone now?

Not yet. Wait for the water to recede, then remove mud, wash and dry. Treating a wet room will not give full results and mold will return.

3. Some dorm rooms are still occupied. What then?

Only empty rooms or zones that can be closed are treated. Occupants of a treated room must leave during treatment and ventilation. The team helps plan the order of zones.

4. How long does it take?

A typical cycle is about 30 minutes per zone, plus preparation and ventilation time.

5. After ozone, do we still need disinfectant?

Yes. Washing and surface disinfection are still necessary. Ozone is an added step afterward to deal with airborne germs and hard-to-reach spots.

6. Someone at home has diarrhea after the flood. What should we do?

Give oral rehydration salts and see a doctor, especially for young children, elderly people and pregnant women. Ozone treats the house, not illness.

7. Is there a promotion for multiple rooms?

Ozone jobs worth 15,000 baht or more receive a free medical-grade disinfectant spray.

Plan ozone disinfection in Nakhon Nayok with WHD

Send photos and describe your rooms on LINE. The team will help split the work into zones and arrange a date to travel to Nakhon Nayok.

See the Ozone Disinfection Service

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

Related services

• Residential and building ozone disinfection
• Disinfection service
• Chemgene disinfectant
• Contact us

References

• Bangkokbiznews, DDPM flood situation: bangkokbiznews.com/news/news-update/1254629
• Thai PBS, flooding and dam releases: thaipbs.or.th/news/content/558960
• CDC Floods: cdc.gov/floods
• Department of Disease Control, Thailand: ddc.moph.go.th
• Department of Health, Thailand: anamai.moph.go.th