The 2026 Ban Phaeo Flood: The Worst in About 35 Years

According to Siam Rath, on 27 September 2026 residents of Lak Sam, Ban Phaeo and Kaset Phatthana subdistricts in Ban Phaeo District said this was the heaviest flooding in about 35 years, since 1991 (2534 in the Thai calendar). Water entered homes, 100 relief kits were distributed to vulnerable residents, and the provincial governor was preparing to declare a disaster zone. The causes were continuous rain, runoff from upstream areas and drainage that could not keep up.

Nationally, the Department of Disaster Prevention and Mitigation (DDPM), as of 06:00 on 7 October 2026, reported 27 provinces plus Bangkok affected, covering 123 districts, 984 subdistricts and 1,154,875 households, with more than 3.1 million people affected. Figures change daily, so check the latest provincial announcements.

Ban Phaeo is a farming district with many vegetable plots, orchards and raised-bed gardens. Homes range from single-storey garden houses to two-storey houses and shophouses. Many have air conditioners in ground-floor bedrooms, with outdoor condensing units on low bases beside the house. When floodwater stays for days, outdoor units can be submerged, muddy water can back up the AC drain line, and constant high indoor humidity turns the inside of the indoor unit into an easy breeding ground for microbes.

Example Case: A Bedroom AC That Smells Sour After the Flood

A typical scenario (an illustrative example, not an interview with any specific resident)

Noi grows vegetables in Lak Sam. Her single-storey house sits slightly above ground and has two air-conditioned bedrooms, with the outdoor units on a concrete pad beside the house. In late September 2026 the rain did not stop and water from higher ground collected around the village. Water rose almost to knee height inside the house and half-submerged the outdoor units. The family slept at a relative's home for several nights.

When the water receded, Noi and her husband washed out the mud, scrubbed the floor and wiped the furniture, then switched on the bedroom AC because the heat was stifling. The moment it started, the air smelled sour and musty, like a soaked rag. Within a few days water began dripping from the unit onto the headboard. Her teenage son, who wears contact lenses, complained of a red, irritated eye, while her diabetic father sneezed every morning.

Noi opened the front cover. The filter was coated grey, the cylindrical blower wheel had rows of black specks, and a torch revealed sheets of pink-orange and grey slime in the drain pan. The drain line was clogged with silt. She sprayed air freshener into the vents, which smelled pleasant for a moment before the mustiness returned even stronger.

This happens often in homes that have just been through a flood, whether in Lak Sam, Ban Phaeo or Kaset Phatthana. The air conditioner is easy to forget, yet it blows air across moisture and microbes straight into the bedroom every night.

What Is Fusarium, and Why Is It in the Air Conditioner?

Fusarium is a group of fungi common in soil, water and plants. Thai farmers know the name because it causes several crop diseases, such as wilt, root rot and stem rot in vegetables and fruit trees. In a farming area like Ban Phaeo, when floodwater carries soil and plant debris into homes, soil microbes can come along too.

Fusarium likes moisture and standing water, so indoors it is often found where water sits and slime, or biofilm, forms: AC drain pans and drain lines, bathroom sink drains, washing-machine door seals, humidifiers and water storage tanks. An air conditioner offers everything a mold needs: water condensing on the cold coil whenever it runs, dust and organic matter on the filter, and a dark, enclosed interior. After a flood, with high room humidity and a blocked drain line, water sits in the pan longer and molds and bacteria grow better than usual.

You might see slime in the drain pan, white, pink, pale purple or orange fuzz or spots on damp surfaces, black specks on the blower wheel and a sour, musty smell when the unit starts. However, slime and specks inside an AC are usually a mix of several molds and bacteria, and colour cannot identify the organism. Only laboratory testing confirms the species.

Where Fusarium and AC Mold Hide After the Ban Phaeo Flood

• The drain pan under the evaporator coil, where water sits longest, especially when the drain line is clogged with mud or silt.
• The AC drain line running to the ground or a drain, where muddy water may have backed up during the flood.
• The evaporator coil and aluminium fins, where wet dust becomes a microbial deposit.
• The blower wheel that pushes air into the room. Black specks there mean germs and odour are blown out every time it runs.
• The air filter, which traps dust and spores and becomes a mold bed when damp.
• Submerged outdoor units, which do not blow into the room but hold mud and need an electrical safety check before use.

Warning signs include a musty or sour smell in the first minutes of operation, water dripping from the unit, weak cooling from clogged coils and filters, black specks at the vents, and sneezing or congestion that happens mainly when sleeping in the air-conditioned room.

Is Fusarium Dangerous? Symptoms to Watch, Especially the Eyes

Most AC mold affects people through the air they breathe, causing allergy and airway irritation: sneezing, congestion, runny nose, coughing, throat irritation and possible asthma flare-ups. The World Health Organization links indoor dampness and mold to these respiratory symptoms.

With Fusarium, doctors pay particular attention to fungal infection of the cornea (fungal keratitis). This is most often seen in contact lens wearers with poor lens hygiene, or in people whose eyes are injured by plant matter, twigs or soil, which is worth knowing for anyone who works in gardens or fields. Fusarium can also cause nail infections and infections of skin wounds, and, rarely, serious infections in people with severely weakened immunity, such as patients with blood cancers or those on immune-suppressing medicines.

Symptoms to watch after a flood:

• A red, painful or irritated eye, blurred vision, sensitivity to light, or a white spot on the cornea, especially in contact lens wearers
• Sneezing, congestion or coughing mainly in the air-conditioned room
• Discoloured or thickened toenails, or inflamed skin around the nails after wading
• Flood-exposed wounds that become swollen, red, hot or pus-filled

People at higher risk include contact lens wearers, young children, older adults, people with diabetes, people with asthma or allergies, and people with weakened immunity.

Important: If an eye becomes red, painful or blurry after the flood, especially in a contact lens wearer, remove the lenses and see an eye doctor promptly. Do not self-treat with pharmacy eye drops. Inflamed wounds, fever or breathing difficulty also need a doctor. Ozone treatment is home care, not medical treatment.

Contact lens advice during floods: never rinse or store lenses in tap water or water from a tank, use freshly opened lens solution, wash hands with soap and dry them before touching lenses, replace lens cases that may have touched floodwater, and consider wearing glasses until the home is clean again.

Why Spraying the AC, or Ozone Alone, Does Not Fix a Musty Air Conditioner

1. Air freshener masks odour briefly. The slime in the drain pan and the standing water remain, and the smell returns within hours.
2. Washing only the filter helps a little, but the drain pan, coil, blower wheel and drain line stay dirty.
3. Running the AC right after the flood, especially if the outdoor unit was submerged, risks short circuits and damage. A technician must check it first.
4. Spraying strong chemicals into the unit yourself can corrode the aluminium fins or leave residue blown into the bedroom.
5. Leaving the drain line blocked lets water overflow the pan onto walls and floors, which then grow mold too.
6. Using ozone without cleaning the AC first. Ozone helps with room air and odour, but it does not scrub off slime or biofilm stuck in the drain pan. The source stays inside the unit.

The principle is to remove the source by real cleaning, then use ozone for the air and lingering odour in the room. This matches CDC advice to clean and dry and to have flooded heating and cooling systems inspected before use.

The Right Order: Electrical Check, AC Cleaning, Room Cleaning, Drying, Then Ozone

1. Do not run an AC whose outdoor unit was submerged until an AC technician or electrician has checked the wiring and the unit.
2. Have the AC professionally cleaned: filter, evaporator coil, blower wheel and drain pan, with the drain line flushed clear, and mud washed off the outdoor unit.
3. Clean the room. Wash out mud, discard mattresses, carpets and materials soaked for long, and check the wall below the unit where water dripped.
4. Dry thoroughly with ventilation, fans and a dehumidifier.
5. Deal with other damp spots, including sink drains, washing-machine seals and water tanks.
6. Ozone treatment in an empty room once the AC and room are clean and dry, to reduce airborne germs, mold spores and remaining musty odour.
7. Keep it up: wash the filter every two to four weeks and book regular AC cleaning.

How Ozone Helps a Room with a Musty AC Smell

Ozone (O3) is a fast-reacting oxidising gas. Released into a closed room, it spreads through the space, including around the AC unit, vents, bed gaps and curtains, reacting with microbial cell structures and odour molecules before breaking down into oxygen (O2). It leaves no chemical residue.

According to the company's certification data, the World Health Disinfection ozone service was tested by Thailand's Department of Medical Sciences and Intertek (UK) and eliminated the tested viruses, bacteria and fungi by 99.99%. This article does not claim test results against Fusarium itself. Fusarium belongs to the fungi group the service targets, and you can request the test data from WHD or see the certification page.

What ozone helps with

• Reducing airborne germs and mold spores in the bedroom after AC and room cleaning
• Reducing musty, sour and muddy odours in curtains, bedding and furniture
• Treating microbes on surfaces the gas can reach, such as walls, floors and room contents
• Getting bedrooms back into use without chemical residue

What ozone does not do

• It does not replace AC cleaning, scrub slime from drain pans, or clear blocked drain lines.
• It does not replace an electrical check of a flooded AC.
• It does not penetrate deep into materials, dry the room, or remove mold toxins.
• It does not replace seeing a doctor, especially for eye symptoms.

Is Ozone Dangerous? Safety Rules for Every Job

• The room must be empty: no people, pets or plants during treatment.
• The room stays closed for the full cycle, with a warning sign on the door. AC and fan settings during treatment follow the technician's instructions.
• Ventilate before re-entry, waiting for ozone to break down and airing the room for the time the technician sets.
• Clean and dry first: the AC is already cleaned, with no mud, standing water or wet mattresses in the room.
• Remove medicines, food and contact lenses, plus anything the owner is concerned about.

Following these rules makes ozone a controlled step. Everyone stays outside during the cycle and returns only once the air is ready.

WHD's Post-Flood Ozone Process for Ban Phaeo, Samut Sakhon Homes

1. Survey. Send photos of the rooms, the AC units and any smelly or moldy spots via LINE @whd268 or call 065-556-6294. The team asks about room size, number of rooms and whether the AC has been cleaned.
2. Confirm cleaning and drying. The team recommends AC cleaning and an electrical check first and advises which materials to discard.
3. Empty the room. People, pets and plants leave. Cabinets and drawers you want treated are opened.
4. Seal the room. Windows and vents are closed, the generator is placed and a no-entry sign goes up.
5. Run the ozone cycle, about 30 minutes per zone depending on room size and conditions.
6. Ventilate. The machine is switched off, ozone breaks down and the room is aired as directed.
7. Re-entry. Once the technician confirms, the owner checks the smell and receives AC and humidity care advice.

WHD is based in Bang Khae, Bangkok 10160, with no branch in Samut Sakhon. Jobs in Ban Phaeo and nearby areas are booked by phone or LINE according to the schedule, and same-day arrival is not guaranteed. Pricing is by quotation after assessment. See the residential ozone disinfection service.

10 Reasons Ban Phaeo Homes Should Consider Ozone After AC Cleaning and the 2026 Flood

1. The bedroom is where you breathe longest. After AC cleaning, post-flood ozone treatment helps with the room air before you sleep there again.
2. It reduces sour, musty odour in curtains and bedding that AC cleaning alone may leave behind.
3. It reduces spores stirred up during AC and room cleaning.
4. It leaves no chemical residue. Ozone reverts to oxygen, suitable for children's and older adults' rooms after ventilation.
5. It is backed by company certification: 99.99% against the tested viruses, bacteria and fungi, according to the company's data.
6. It takes about 30 minutes per zone, so you can return the same day after ventilation.
7. It reaches spots you cannot wipe, behind cabinets, under beds and around the AC unit.
8. It suits homes with diabetes, allergies or older adults, reducing airborne triggers alongside medical care.
9. It shows whether the source is truly gone. If odour returns quickly after treatment, there is still a damp source to find.
10. You get honest advice first. The WHD ozone team recommends AC cleaning first and does not sell more than you need.

Before and After: A Bedroom with a Musty AC After the Flood

Example Case, Continued: Noi's Bedrooms After the Full Process

Noi switched the AC off immediately and called a technician. He checked the submerged outdoor units and wiring first, then removed and washed the filters, cleaned the coil and blower wheel, scrubbed the slime from the drain pan and flushed silt out of the drain line until it ran freely. The mattress soaked by drips was discarded, and the stained wall below the unit was wiped and left to dry. Her son removed his contact lenses and saw an eye doctor as advised.

Once the rooms were dry, the family booked ozone treatment. Everyone worked in the vegetable plots while the technician treated both bedrooms zone by zone and then ventilated for the set time. That night the AC started without the sour smell. Noi now washes the filters monthly. (This is an example case. Results depend on each home's condition.)

AC and Room Checklist for Fusarium: Before and After Ozone

Before ozone

• Do not run an AC with a submerged outdoor unit until a technician checks it
• Clean every AC part: filter, coil, blower, drain pan and drain line
• Wash out mud and discard mattresses and carpets soaked for long
• Check the wall under the unit where water dripped
• Clean sink drains, washing-machine seals and water tanks
• Ventilate and use a dehumidifier until the room is dry
• Contact lens wearers: replace any case that may have touched floodwater

On treatment day

• All people, pets and plants leave the room
• Remove medicines, food and contact lenses
• Keep windows shut, set the AC as the technician advises and do not enter during the cycle

After ozone

• Wait for rest and ventilation time set by the technician
• Wash AC filters every two to four weeks
• Watch for drips or odour when the AC starts and check the drain line if they return
• See a doctor if eye redness, eye pain or allergies do not improve

FAQ: AC Mold, Fusarium and Ozone After the Ban Phaeo Flood

Why does my AC smell musty after the flood?

Usually slime and mold in the drain pan, coil, blower wheel and filter, plus a drain line clogged with mud. Have a technician clean every part of the unit.

What is Fusarium mold and is it dangerous?

It is a soil and plant fungus that likes damp places, including drain pans and pipes. Its spores can trigger allergies, and doctors know it as a cause of fungal keratitis, particularly in contact lens wearers. People with weakened immunity should take extra care.

My eye is red and painful after the flood. What should I do?

Remove contact lenses at once and see an eye doctor promptly. Do not self-treat with pharmacy eye drops. Corneal infections need medical treatment.

Can I use my AC if the outdoor unit was underwater?

No. Have an AC technician or electrician check the wiring and unit first, for safety and to prevent damage.

Does ozone get rid of mold in the air conditioner?

Ozone reduces airborne germs, mold spores and musty odour in the room, and according to the company's certification data it achieved 99.99% against the tested viruses, bacteria and fungi. But it does not replace AC cleaning because it does not scrub slime from the drain pan. Clean the AC first, then treat the room.

Is ozone dangerous? Can I sleep in the room during treatment?

No. The room must be empty of people, pets and plants, closed for the whole cycle, and re-entered only after ventilation as the technician directs.

How much does bedroom ozone treatment cost?

It depends on room size, number of rooms and site conditions. WHD gives a quotation after assessment. Send photos via LINE @whd268 or call 065-556-6294.

Is there an ozone service near me in Ban Phaeo, Samut Sakhon?

WHD is based in Bang Khae, Bangkok, with no Samut Sakhon branch, but it books jobs in Ban Phaeo and nearby areas by phone or LINE according to its schedule. Same-day arrival is not guaranteed.

What is the pink slime in my AC drain pan?

Usually a biofilm containing a mix of bacteria and molds. Colour cannot identify the organism. Have a technician scrub the pan and flush the drain line.

When should I clean my AC after a flood?

Before using it again after the water recedes, especially if it smells, drips, or the outdoor unit was submerged.

Musty AC or Moldy Bedroom in Ban Phaeo After the 2026 Flood? Talk to WHD

Send photos of the room and the AC unit, and the team will help you plan the order of work and schedule ozone after AC cleaning.

See the Post-Flood Ozone Service

Call 065-556-6294 | LINE @whd268

World Health Disinfection, Bang Khae, Bangkok 10160. Upcountry jobs booked by phone or LINE. Pricing by quotation.

Related Links and References

• Residential and building ozone disinfection service
• Ozone cleaning service
• Company certification documents
• Contact us
• Siam Rath (27 Sep 2026): Ban Phaeo, Samut Sakhon sees worst flooding in about 35 years
• Government Public Relations Department: DDPM flood situation as of 7 Oct 2026
• CDC: Floods and cleanup safety
• Department of Disease Control, Thailand

Note: area details and figures follow the dates in news and DDPM reports and change daily. This article is general information, not medical advice.