A typical scenario (an illustrative example based on common situations, not a review from a specific customer)

Three weeks on the upper floor of a wooden house in Phak Hai

Uncle Sompong and Auntie La-iad, both in their seventies, live in a two-storey wooden house beside the Noi River in Phak Hai district. When the water began to rise, they did what they have always done: instead of evacuating, they moved upstairs, tied a boat to the staircase, cooked rice on a camping gas stove and waited for the water to go down on its own. Their granddaughter, who works in Bangkok, phoned every day, worried.

The ground floor went under almost to the window sills, and the water stayed there for weeks. What Uncle Sompong had not expected was that even though the upper floor stayed dry, moisture rose from the water below all the time. Blankets that had been dry were damp every morning. A white bloom appeared along the seams of the upstairs floorboards. The old teak wardrobe began to smell musty. Auntie La-iad, who has asthma, coughed more at night, and a scrape on Uncle's leg, picked up while rowing to buy supplies, became swollen and red.

Their granddaughter insisted that Uncle go straight to the district hospital, which was exactly the right call. The question that followed was harder: when the water finally recedes weeks from now, how do you make a house that has been soaking for so long safe again for two elderly people?

Stories like this are found across Ayutthaya, especially in districts west of the Chao Phraya and along the Noi River, such as Sena, Bang Ban, Phak Hai and Bang Sai, where water tends to stay for a long time. There are many other versions, too: rented rooms for factory workers in Bang Pa-in, Wang Noi and Uthai, riverside restaurants on the old city island, and farmhouses in Lat Bua Luang, Bang Pahan, Tha Ruea, Nakhon Luang and Phachi.

Ayutthaya flood 2026: 13 districts and almost 45,000 households

Nationally, DDPM reported on 2 October 2026 that 31 provinces plus Bangkok were flooded, affecting 1,245,581 households or 3,535,206 people. The main causes were heavy to very heavy rain and runoff from the north moving down the main rivers.

For Ayutthaya, 44,865 households across 13 districts make it one of the most widely affected provinces in the central region, and DDPM noted that water was still rising, which means many areas will be living with floodwater for some time yet.

What makes Ayutthaya different is its geography: a low, flat plain where several rivers flow through and meet, including the Chao Phraya, Pa Sak, Lopburi and Noi, laced with canals and broad rice fields. When water comes in, it rarely leaves after a day or two; it often stands for weeks. Housing ranges from traditional stilt houses that cope with water well, to concrete homes, townhouses, housing estates, rented rooms and dormitories that have grown up alongside the industrial estates and factories in the Bang Pa-in, Wang Noi and Uthai area.

Ayutthaya is also a world-famous tourist city, full of historic sites, temples, riverside restaurants, homestays and hotels. Recovery after a flood here is not just about homes. It is about the tourism economy and community businesses as well.

Why long-flooded Ayutthaya homes carry more germs

How long a house sits in water has a big effect on both the germ load and the damage. When water stands for weeks, three things happen at once.

First, water soaks deep into materials. Timber, clay brick, plaster and gypsum absorb far more water than in a house flooded for a day or two, and take much longer to dry once the water goes.

Second, stagnant water turns foul. Water that stands for a long time loses oxygen. Organic matter in it rots, producing strong rotten-egg and drain smells, and it becomes a reservoir for bacteria.

Third, damp climbs upstairs. Even if the upper floor never gets wet, air humidity stays high around the clock, so mold grows on fabrics, mattresses, leather and wood in the rooms where people are actually living.

Bacteria from wastewater and sewage

Ayutthaya floodwater flows through septic tanks, bathrooms, duck and chicken farms, animal pens and community drains, carrying E. coli, Salmonella and other gut bacteria into homes. These cause diarrhoea, stomach cramps, vomiting and fever. People who stay in their homes during a flood and use the surrounding water to wash dishes or hands are at high risk. Use only bottled or boiled water.

Leptospirosis

Ayutthaya's rice fields and riverside communities have plenty of rats. When water stands for a long time, Leptospira bacteria from rat urine spread through it. People who row, wade out for supplies or move belongings around can be exposed through small cuts on hands and feet. Symptoms are sudden high fever, headache, severe calf pain and red eyes. Thailand's Department of Disease Control stresses that anyone with these symptoms after flood exposure must see a doctor promptly and mention the wading. Wounds that become swollen, red or pus-filled also need a doctor's attention.

Gut viruses such as norovirus and rotavirus

When several families share a shelter or a single upstairs bathroom, these viruses pass quickly from person to person through hands, food and shared surfaces. Washing hands with soap and keeping separate dishes for anyone with diarrhoea help limit spread.

Mold: the biggest problem in long-flooded homes

Molds such as Aspergillus and Penicillium thrive on materials that stay damp continuously, which makes a house soaked for weeks ideal for them. Mold can appear on ground-floor walls, under timber floors, in ceilings and on upstairs furniture. The effects include a blocked nose, sneezing, coughing, itchy eyes, rashes and asthma attacks. Older adults, people with lung disease and those with weakened immunity should avoid spending time in heavily molded rooms.

Musty and stagnant-water odours

Long-flooded houses often have two layers of smell: the stagnant-water and mud smell from decomposing organic matter, and the musty smell from mold. Both penetrate deep into wood and plaster, so even after the floor has been washed, odour keeps seeping out of walls and floorboards.

Who needs extra care

Older people who choose to stay at home through the flood, young children, pregnant women, people with diabetes (whose wounds heal slowly), heart, kidney or lung disease, and anyone on immunosuppressive medicine. Where possible, they should stay somewhere dry and safe until the house has been restored.

The impact on Ayutthaya families and businesses

Health: Illness does not end when the water goes. People who have lived with damp and mold for weeks may have ongoing breathing problems, which may not improve if they move back into a house that has not been properly restored.

Cost: Warped floorboards, flaking plaster, sagging ceilings and moldy cabinets and beds all need budgeting. The longer mold is left, the more has to be torn out.

Time and work: Factory staff in Bang Pa-in, Wang Noi and Uthai may need leave to restore their homes, or have to find temporary accommodation.

Tourism: Riverside restaurants, cafés, homestays and hotels on the city island need to reopen quickly and well. Visitors do not want to eat in a room that smells damp.

Landlords: Owners of rented rooms and apartments near the industrial estates risk tenants moving out, and new ones being hard to find, if rooms smell or show mold.

Families: Children working far from home worry constantly about elderly parents living in a damp house, and that stress reaches everyone.

Common fixes for long-flooded homes that fall short

Washing the floor and moving furniture straight back: A floor that looks dry on top may still be wet underneath, especially timber floors and tiles laid over another surface. Moving furniture back too soon traps the moisture.

Using very strong bleach: Higher concentration does not mean better results. It increases the risk of irritating your airways and still cannot reach inside timber or walls.

A day or two of sunshine: Walls that soaked for weeks need a long time to dry. Brief airing is not enough.

Perfume, incense or camphor: These help only briefly; the source remains in the materials.

Repainting or re-wallpapering immediately: If the wall is still damp, mold keeps growing underneath and soon shows through again.

How to tell whether a long-flooded Ayutthaya house is really dry

Because ozone works best in a house that has already been cleaned and dried, the most common question after a long flood is simple: how do we know it is dry enough? There is no single sign, but several clues help. Press a hand flat against the lower part of a wall for a minute; if it feels cool and clammy compared with the upper wall, moisture is still inside. Look at the tide line: if the plaster below it is darker than above, it is still wet. Lift a floorboard or a loose tile in a low corner and check underneath. Smell cupboards and drawers after they have been closed overnight. If a musty smell builds up again by morning, the drying is not finished.

For timber houses along the Noi and Chao Phraya, give the under-floor space plenty of airflow, and do not lay plastic sheets or new flooring over boards that are still damp. For brick and plaster homes, cutting away the lowest strip of soaked plaster or gypsum often speeds up drying dramatically. Cheap moisture meters are also available and are a useful way to compare readings from week to week. Share these observations with the team when you book, as they help decide when ozone treatment will be most effective.

WHD ozone disinfection for homes and buildings in Ayutthaya

World Health Disinfection (WHD) is based in Bang Khae district, Bangkok 10160, and has no branch in Phra Nakhon Si Ayutthaya. Homes, rented rooms, restaurants, hotels, homestays and buildings in Ayutthaya can contact the team to plan a residential and building ozone disinfection service. Travel, coverage and the appointment date are confirmed by phone on 065-556-6294 or LINE @whd268 according to actual road conditions. The team cannot promise same-day arrival, especially while water levels remain high.

How ozone works

Ozone (O3) is a strongly oxidising gas. Released into a closed space at a controlled concentration, it attacks the cell structures of bacteria, viruses and mold and breaks down odour molecules. As a gas, it reaches into wood seams, under floors, behind cabinets and into ceilings. It then reverts to oxygen (O2), leaving no chemical residue. According to the test results certified for the company by Thailand's Department of Medical Sciences and Intertek (UK), the system eliminates viruses, bacteria and mold at 99.99%. You can read more about the ozone disinfection machines.

Service steps

1. Consult and assess: Send photos, the floor area, number of storeys, water height and how long the house was under water, via LINE.
2. Get the house ready: Remove mud, wash, discard damaged materials and dry as far as possible. Long-flooded houses may need more drying time than usual.
3. Clear people and animals: Every person, pet and plant leaves. Treatment is carried out only in an empty, closed space.
4. Ozone treatment: About 30 minutes per zone, depending on size and condition.
5. Rest and ventilate: Wait for the ozone to break down and air the space as advised before re-entering.

Important: ozone treatment follows mud removal, washing and drying. It does not replace cleaning, structural repairs or medical treatment. Anyone with fever, calf pain, diarrhoea, infected wounds or breathing difficulty must see a doctor.

Promotion: ozone jobs of 15,000 baht or more receive a free medical-grade disinfectant spray.

10 reasons Ayutthaya homes should use ozone after the water drops

1. It helps long-flooded homes: When germs have sunk deep into materials, a gas reaches places wiping cannot.
2. It covers both floors: Damp rising upstairs grows mold in bedrooms too; treatment can cover every level.
3. Viruses, bacteria and mold together: 99.99% according to the company's certified tests. Details are on the ozone service page.
4. It reduces stagnant-water and musty smells: Ozone breaks down odour molecules in the air and on surfaces.
5. No residue: Safe for elders and children to return once the ventilation period is over.
6. It suits riverside restaurants and cafés: Helping businesses on the city island welcome tourists back sooner, without a damp smell.
7. It suits rented rooms and dormitories: Landlords near the estates in Bang Pa-in, Wang Noi and Uthai can treat room by room before tenants return.
8. It helps items you cannot wash: Books, wooden Buddha images, collectibles and textiles that should not touch liquid cleaners.
9. It prepares for repairs: Reducing germs before new flooring or paint. Learn more about using ozone to reduce chemical residue.
10. It reassures the family: Knowing a parent's house has been washed, dried and disinfected in the right order eases a lot of worry.

Before and after: an Ayutthaya riverside house flooded for weeks

Note: results depend on how long the house was flooded, the remaining moisture and the cleaning done beforehand.

Example case: rented rooms near an industrial estate in Uthai

An illustrative example to aid understanding, not a verified customer review.

Noi owns a two-storey building of about twenty rental rooms in Uthai district, mostly let to factory workers. When water flooded the ground floor, those tenants had to stay with friends or go back to their home provinces, and every ground-floor room sat in water for days.

Once the water went down, Noi hired workers to shovel out the mud and wash the rooms. But tenants who came back to look said the rooms still smelled musty, and mold had appeared around bathroom door frames and under the wardrobes. Some decided not to renew.

Noi changed approach. She replaced the swollen bathroom doors, removed the moldy wardrobes, opened every room and ran fans until the walls were dry, then contacted the team to plan ozone treatment one block of rooms at a time. No tenant stayed in any room or corridor being treated, and rooms were shown only after the rest and ventilation period. For a landlord, a tenant walking in and smelling nothing musty makes the decision to come back much easier.

Checklist for Ayutthaya residents: living with the water, and when it drops

If you are staying at home during the flood

• Follow provincial and DDPM announcements and be ready to evacuate when told, especially with elderly or sick family members.
• Drink bottled or boiled water. Never use floodwater for washing dishes or brushing teeth.
• Open upstairs windows during the day to reduce built-up humidity.
• Look after cuts on hands and feet; clean and cover them every time after contact with water.
• Beware of electrical leakage; switch off ground-floor circuits.

When the water drops

• Have an electrician inspect the system before use.
• Wear boots, gloves and a mask during clean-up.
• Remove mud from every corner, including under the house and in floorboard gaps.
• Wash surfaces with clean water and detergent, then disinfect according to the label.
• Discard mattresses, carpets and absorbent materials that were soaked or heavily molded.
• For long-flooded homes, allow more drying time than usual, with fans and dehumidifiers running continuously.
• Check upstairs too, as damp may have grown mold on bedding and furniture.

Ozone day

• Take everyone, pets and plants out of the area.
• Close external doors and windows; open cupboards and drawers.
• Re-enter only after the rest and ventilation period.

After ozone

• Ventilate daily and control humidity.
• Watch for new mold during the first month.
• See a doctor if anyone in the household develops unusual symptoms.

FAQ: ozone disinfection in Phra Nakhon Si Ayutthaya

Q: Does WHD have a branch in Ayutthaya?
A: No. WHD is based in Bang Khae, Bangkok. Customers in Ayutthaya can contact the team to plan service, with travel and dates confirmed on 065-556-6294 or LINE @whd268.

Q: My house was flooded for weeks. Can ozone help?
A: It can help as the final step, but mud must be removed, damaged materials taken out and the house dried first. Long-flooded homes may need longer drying than usual.

Q: Can we stay upstairs during treatment?
A: No. The treated area must be completely empty. If floors are treated one at a time, discuss sealing off areas with the team, and nobody stays in a zone being treated.

Q: How long does one treatment take?
A: About 30 minutes per zone, not counting preparation and ventilation.

Q: After ozone, can we keep the mattress?
A: Mattresses and carpets soaked in dirty water or heavily molded should be thrown away, as WHO and CDC advise. Ozone does not replace discarding damaged items.

Q: Can restaurants on the city island use the service?
A: Yes. Restaurants, cafés, hotels and homestays can plan zone-by-zone treatment while closed.

Q: Any promotion?
A: Jobs of 15,000 baht or more receive a free medical-grade disinfectant spray.

Ayutthaya residents: start your post-flood recovery plan today

Whether your home is in Sena, Bang Ban, Phak Hai, Bang Sai, Bang Pa-in, Uthai, Wang Noi or on the city island, send photos and details so the team can help assess and plan ozone treatment.

View the Ozone Disinfection Service

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

Related links and references

• Residential and building ozone disinfection
• Ozone disinfection machines
• Reducing chemical residue with ozone
• Bangkokbiznews: flood situation report (DDPM data)
• Thai PBS: flood situation
• WHO fact sheets
• Department of Disease Control, Thailand