The 2026 Bangkok and metro flood: facts from news reports

• Thai PBS reported the heaviest rainfall on 25 to 26 September 2026 in Chatuchak (210.0 mm), Wang Thonglang (205.5 mm) and Saphan Sung (203.5 mm). Over 300 mm fell in about 48 hours, and on 26 September all 50 Bangkok districts were declared disaster zones (Thai PBS, Malay Mail).
• Flooded points rose from 43 on the evening of 25 September to 135 on 27 September. On 29 September the disaster declaration was lifted in 21 districts, leaving 29, and DDPM designated 38 districts and 118 subdistricts as flood-assistance zones (Naewna, Thai PBS).
• DDPM data on 6 October 2026 put affected Bangkok households at 329,000 (Bangkok Biz News). Nationally, DDPM at 06:00 on 5 October 2026 reported 26 provinces plus Bangkok affected, totalling 1,270,151 households (Dailynews).
• Examples inside Bangkok: in Bang Kapi, Ramkhamhaeng Soi 19/1 to 43 had 25 to 30 cm of water on 28 September, and the Khlong Chan flats area saw more than 20,000 people affected (Thansettakij, The Standard). In Wang Thonglang, the BMA warned on 27 September to avoid Lat Phrao Soi 87 to 126, flooded 20 cm or more. In Don Mueang, inbound Vibhavadi Rangsit Road between Don Mueang and Lak Si had about 40 cm of standing water on 26 September. In Min Buri, Suwinthawong Road near Hathairat still had 20 cm on 4 October.
• Ramkhamhaeng University: Thai PBS reported flooding from 25 September to 1 October 2026, close to 2 metres at some points, lasting about six days, with more than half of its 65 buildings affected.
• Surrounding provinces: Thai PBS reported Rangsit Market in Pathum Thani almost entirely under water on 27 September as Khlong Rangsit Prayurasak overflowed into roads and homes. Dailynews reported nearly 1 metre of water on Chaeng Watthana Road, Pak Kret, Nonthaburi on 26 September. TopNews reported about 1.5 metres in some zones of the Thana Place and Thana City estates in Bang Phli, Samut Prakan on 1 October, with main pumps out of action because their electrical cabinets were submerged.

The picture is clear: this flood did not stay on the roads. It entered homes, shops, markets, classrooms and housing estates, places that many people share every day.

Example case: a ground-floor apartment off Ramkhamhaeng Road

Note: a typical scenario compiled from common urban flood situations, not a real person's account.

Ton, a thirty-something office worker, rents a ground-floor room in an older apartment block in a soi off Ramkhamhaeng Road. During the heavy rain he waded ankle- to shin-deep water from the soi entrance every evening. The water mixed rain, drain backflow and floating rubbish, and about a hand-span of it entered his room.

Once it receded, Ton mopped the floor with floor cleaner and went back to sleeping with the air conditioner on and the door shut. A week later he woke up congested every morning, black dots had appeared on the wall behind his wardrobe, and his roommate had diarrhoea after eating a boxed meal left on a low table that had been under water. On day ten, a colleague who waded through the same area called in sick with high fever and calf pain, and his doctor asked about wading.

Bangkok life does not pause until homes are dry. People return to work, ride the BTS and share common areas with hundreds of others, so flood germs can travel further than expected.

How we ranked flood germs in Bangkok and nearby provinces

This is an editorial ranking by the World Health Disinfection (WHD) team. It is not official and is not based on case statistics for Bangkok or any province. We weighed:

1. Link to floods in WHO, CDC and Thai Department of Disease Control guidance.
2. Urban context: canal and drain backflow, dense populations, high-rises, sealed air-conditioned rooms, fresh markets and public transport.
3. Severity and at-risk groups: young children, older adults, bedridden patients and people with chronic illness.
4. Ease of spread in condos, offices, schools and common areas.
5. Persistence in the environment, described qualitatively without unsourced figures.

Ask WHD for disinfectant test data on any specific organism, and see a doctor if you feel unwell after flood contact.

The ranking: 10 flood germs in Bangkok and surrounding provinces, 2026

Ordered from what city residents should watch first. Lower positions are not harmless; they affect narrower groups or places.

No. 1: Canal and sewage bacteria such as E. coli (Escherichia coli) and Salmonella

Why it ranks first: this flood mixed in a great deal of overflowing canal water and drain backflow. Urban canals receive wastewater from many communities, so water entering homes carries faecal bacteria. Many shophouses and housing estates also rely on septic tanks that can overflow in deep water.

Where it hides: ground floors of shophouses, townhouses and apartments, downstairs bathrooms, restaurant back kitchens, basement car parks, grout lines and market floors.

Symptoms and who is at risk: diarrhoea, cramps, nausea, vomiting and fever. Young children, older adults and people with weakened immunity risk dehydration; seek care for bloody stools or inability to drink.

Prevention: rubber gloves and boots while cleaning, discarding flood-touched food, handwashing before eating, and not relying on tap water until it is confirmed safe.

Cleaning and spraying: scrape and wash first, then spray. Salmonella is named in CHEMGENE HLD4H product information; E. coli belongs to the bacteria group the product says it covers. Specific test data is available on request.

No. 2: Leptospira, the cause of leptospirosis

Why it ranks here: big cities have large rat populations in drains, markets and rubbish piles. Floods drive rats up and their urine mixes into water people wade through on the way home, so the risk extends beyond clean-up crews to commuters. CDC says symptoms usually start 2 days to 4 weeks after exposure.

Where it hides: standing water in sois, drains, basement car parks, storerooms, back-of-shop warehouses and market floors.

Symptoms and who is at risk: sudden high fever, headache, severe calf pain and red eyes. Long-time waders, people with foot wounds, cleaners and market vendors are most exposed. See a doctor at once for fever after wading and mention it.

Prevention: avoid wading with wounds, wear boots, wash feet with soap on arriving home, store food sealed and remove rat food sources.

Cleaning and spraying: Leptospira is not named on WHD's pages but belongs to the bacteria group the product says it covers. WHO and CDC advise cleaning then disinfecting flood-contaminated surfaces; spraying ground floors, car parks and storerooms after washing reduces germs on surfaces people touch. Ask for specific data if needed.

No. 3: Mold in sealed rooms and high-rises, such as Aspergillus and Stachybotrys

Why it ranks here: many Bangkok homes and condos use gypsum partitions, laminate floors and sealed air-conditioned rooms. Trapped moisture lets mold grow fast; CDC says it can begin within 24 to 48 hours after materials get wet.

Where it hides: lower gypsum walls, behind built-in wardrobes, under laminate, water-stained ceilings, AC ducts, mattresses and carpets in ground-floor units.

Symptoms and who is at risk: congestion, sneezing, coughing, itchy eyes and asthma flare-ups. City residents already sensitive to dust often react more strongly; people with weakened immunity should avoid moldy rooms.

Prevention: open windows, run dehumidifiers, clean air conditioners, and remove soaked gypsum and laminate as a contractor advises.

Cleaning and spraying: after removal and washing, spraying treats remaining mold on frames and surfaces. Product information covers fungi in general; ask for species-specific data.

No. 4: Norovirus

Why it ranks here: condos, dormitories and offices share toilets, lifts and pantries among many people, ideal conditions for norovirus. It is non-enveloped, so it resists soap and alcohol gel better than cold viruses. CDC says symptoms usually begin 12 to 48 hours after exposure.

Where it hides: lift buttons, door handles, taps, shared toilets, office microwaves and food-court tables.

Symptoms and who is at risk: vomiting, diarrhoea and cramps; young children and older adults dehydrate easily.

Prevention: soap-and-water handwashing, prompt vomit clean-up, and sick people staying home and not preparing food for others.

Cleaning and spraying: norovirus is named in the product information, making common-area spraying after cleaning a good fit for condo juristic persons and offices.

No. 5: Respiratory viruses such as influenza, RSV and SARS-CoV-2

Why it ranks here: during floods, Bangkok residents squeeze into trains, vans and offices while exhausted by difficult commutes and cleaning. Sealed, poorly ventilated rooms help viruses spread.

Where it hides: air in closed meeting rooms, handrails, desks, phones, keyboards and nursery toys.

Symptoms and who is at risk: fever, cough, sore throat and breathlessness; babies, older adults and people with heart or lung disease risk severe illness.

Prevention: masks when sick, working from home with fever, ventilation, and asking a doctor about flu vaccination.

Cleaning and spraying: COVID-19, RSV and influenza H1N1 and H5N1 are named in WHD's service and product information, so spraying offices and classrooms before reopening reduces surface germs.

No. 6: Enteroviruses that cause hand, foot and mouth disease

Why it ranks here: the metro area has many childcare centres, nurseries and kindergartens, often on shophouse ground floors that flooded. Hand, foot and mouth disease is common in young children in the rainy season, and the virus resists plain-water wiping.

Where it hides: toys, crawling mats, children's tables and stair rails.

Symptoms and who is at risk: fever, mouth sores and blisters on hands, feet and buttocks, mainly in under-fives. Seek care immediately for high fever, drowsiness or frequent vomiting.

Prevention: keep sick children home as advised, wash hands after nappy changes and clean toys daily.

Cleaning and spraying: hand, foot and mouth virus is named on WHD's disinfection service page, per the service information, so spraying suits childcare centres reopening after floods.

No. 7: Hepatitis A virus

Why it ranks here: street-food stalls, curry-rice shops and market stalls that reopen washing utensils in unsafe water can become transmission points. The virus is non-enveloped and hardy; CDC gives a typical incubation of 15 to 50 days.

Where it hides: utensils, chopping boards, ice buckets, water tanks and prep surfaces.

Symptoms and who is at risk: fatigue, poor appetite, upper-right abdominal pain, jaundice and dark urine; people with liver disease should be careful.

Prevention: safe water, freshly cooked food, and operators cleaning ice buckets and all utensils before reopening.

Cleaning and spraying: not named on WHD's pages but within the virus group the product says it covers. Spraying kitchens and shopfronts after washing adds confidence; specific data is available on request.

No. 8: Wound germs such as Staphylococcus aureus and the tetanus germ (Clostridium tetani)

Why it ranks here: city floodwater hides broken glass, open drain covers, nails and sharp rubbish, and people wading in sandals can be cut without noticing. Soaked wounds easily become infected, and CDC says tetanus symptoms usually start 3 to 21 days after infection.

Where it hides: mud and debris in sois, car parks and shop floors.

Symptoms and who is at risk: red, swollen, pus-filled wounds, fever, or muscle stiffness and a locked jaw; people with diabetes and older adults need extra care.

Prevention: closed shoes or boots, immediate wound washing, and asking a doctor about tetanus vaccination.

Cleaning and spraying: wound care is medical; spraying only reduces surface germs after washing. Staphylococcus belongs to the bacteria group the product says it covers; we do not claim spraying destroys tetanus spores. Removing mud is what works.

No. 9: Legionella pneumophila in high-rise water tanks and cooling towers

Why it ranks here: Bangkok has many offices, hotels and tall condos with storage tanks and cooling towers. When systems stop because of power cuts or flooded plant rooms, stagnant water favours Legionella. The risk is limited to large buildings, hence its lower rank.

Where it hides: basement and rooftop tanks, unused pipes, shower heads in closed rooms and cooling towers.

Symptoms and who is at risk: pneumonia-like fever, cough and breathlessness; older adults, smokers and people with lung disease are at higher risk.

Prevention: flush every outlet, clean tanks, and have water-system specialists check cooling towers before reopening.

Cleaning and spraying: surface spraying is not water-system treatment, so handle plumbing separately. Spraying covers bathrooms, lobbies and flooded common areas.

No. 10: Skin and foot fungi such as dermatophytes and Candida

Why it ranks here: Bangkok commuters who wade through sois each morning and then sit all day in wet closed shoes are prone to "flood foot" and fungal infections. Rarely serious for most people, it is a real concern for people with diabetes.

Where it hides: damp shoes, socks, doormats, bathroom floors and locker rooms.

Symptoms and who is at risk: itching between toes, peeling, soggy skin and odour.

Prevention: keep spare shoes at work, wash and dry feet, change socks often.

Cleaning and spraying: bathroom floors, locker rooms and building entrances are worth spraying after washing. These belong to the fungi group the product says it covers; ask for specific data.

Summary by building type

An editorial ranking, not official statistics.

Why soap, floor cleaner or bleach alone falls short in city buildings

• Soap lifts dirt but is not designed to destroy every germ; norovirus and hand, foot and mouth virus resist it better.
• Bleach is weakened by mud and organic matter from canals and sewage.
• Never mix bleach with ammonia or acids; in poorly ventilated condo rooms the resulting gas is even more dangerous, as CDC warns.
• Common areas are too large to wipe evenly: lobbies, lifts, car parks and corridors.
• Bleach does not fix mold in porous materials; CDC advises removing them.

WHD post-flood disinfection spraying in Bangkok and surrounding provinces

WHD's disinfection spraying service covers homes, condos, shops, offices and buildings, carried out by trained technicians who, according to the service information, use spraying and/or ULV (Ultra Low Volume) fine-mist fogging. The product is CHEMGENE HLD4H, a UK medical-grade disinfectant containing Benzalkonium Chloride and Didecyldimethylammonium Chloride, described as broad-spectrum against viruses, bacteria and fungi. Named organisms include SARS-CoV-2, Human Coronavirus 229E, RSV, influenza H1N1 and H5N1, HIV, norovirus, hand, foot and mouth virus, vaccinia virus, mycobacteria, Salmonella and Bordetella pertussis. The service page states 99.99% efficacy; the product page states 99.85% against COVID-19 within one minute. The service page cites the Department of Medical Sciences, Mahidol University, NHS England and EN 14476:2013+A2:2019, and lists customers such as hospitals, schools, malls, airports, offices, airlines, banks and residential buildings. For other organisms, ask for test data.

1. Survey: water line, building type, common areas, backflow points and early mold.
2. Mud removal and washing first; damaged materials taken out.
3. Zoning: people and pets leave the zone; condos and offices can be done floor by floor or out of hours.
4. Spraying: floors, walls, furniture, bathrooms, kitchens, lifts, lobbies and car parks.
5. Re-entry: about 30 minutes per the service information, following the technicians' on-site timing.

We do not claim spraying leaves no residue; ask about food-contact surfaces and toddler rooms. Anyone unwell should see a doctor, as spraying is not treatment. For musty sealed rooms, consider residential ozone disinfection. The service includes a free CHEMGENE spray and WELLGIENIC wet tissues, and a tax invoice is available.

10 reasons Bangkok and metro residents should spray after floods

1. Canal water and sewage bring many germ groups at once; spraying covers several together.
2. Large condo common areas are reached more evenly by ULV mist than by wiping.
3. Sealed AC rooms invite mold; spraying after removal treats what remains.
4. Respiratory viruses are named in the disinfection service information.
5. Restaurants and market stalls reopen with more confidence.
6. Suits childcare centres, with hand, foot and mouth virus named.
7. Out-of-hours appointments keep offices running.
8. On-site assessment of what to remove or re-wash.
9. Quick re-entry, about 30 minutes per the service information.
10. Tax invoices for juristic persons and companies. Request a quote.

Before and after spraying

Example case: a vegetable stall in a suburban fresh market

Note: an illustrative example, not a real customer review.

Auntie Sri sells vegetables in a suburban fresh market that flooded almost completely. Afterwards her wooden stall was caked in mud, rotting produce and rubbish lay underneath, and there were clear signs of rats. She and her son washed the stall with water and detergent but still worried about leptospirosis and the lingering smell. The team surveyed with several neighbouring vendors, advised discarding rotten crates, clearing rubbish, and scrubbing the concrete floor and drains, then sprayed the whole zone at night after closing while all vendors stayed out. Treating the zone together, she said, felt safer than cleaning one stall alone, because germs do not stop at stall boundaries.

Checklist for Bangkok and metro homes and buildings

• Keep power off on flooded floors until an electrician checks, especially submerged cabinets and plant rooms.
• Boots, gloves and a mask; remove all mud.
• Discard flood-touched food, medicine and soaked porous items; remove damaged gypsum and laminate.
• Clean air conditioners and drip trays, flush pipes and clean tanks.
• Condo juristic persons should notify residents of common-area spraying schedules.
• After spraying: re-enter on time, rinse food-contact surfaces, check for mold weekly, keep spare shoes at work, and see a doctor for fever, calf pain, diarrhoea, jaundice or infected wounds.

FAQ

My condo unit is high up and stayed dry. Do I need spraying?
Your unit may not, but flooded shared areas such as lobbies, car parks and lifts should be cleaned and sprayed. Talk to your juristic person.

I wade through my soi daily but my home is dry. What should I watch?
Foot wounds, leptospirosis and flood foot. Wash feet with soap on arrival and see a doctor for fever or calf pain.

Can companies get a tax invoice?
Yes, per the service information.

Can you spray out of hours or at weekends?
Appointments can be arranged with the team, especially for offices, shops and markets.

Do you serve Nonthaburi, Pathum Thani and Samut Prakan?
Ask about service areas and book by phone or LINE.

How long must a restaurant close after spraying?
About 30 minutes per the service information, then rinse utensils and prep surfaces before opening, following the technicians' timing.

Water gone in Bangkok and nearby provinces? Let WHD finish the job

Homes, condos, shops, markets, offices and schools: get advice and book a site survey today.

See the WHD Disinfection Service

Call 065-556-6294 | LINE @whd268

Related services and references

• WHD disinfection spraying service | Residential ozone disinfection
• Thai PBS rainfall: 558661; flood points and zones: 558668, 558864, 558867; roads: 558585
• Malay Mail, 26 Sep 2026: malaymail.com
• Naewna: naewna.com; Bangkok Biz News: bangkokbiznews.com
• Thansettakij: thansettakij.com; The Standard: thestandard.co; MGR Online: mgronline.com; Siam Rath: siamrath.co.th
• Thai PBS, Ramkhamhaeng University: 559039; Rangsit Market: 558685
• Dailynews, Chaeng Watthana: 6223597; DDPM national update: 6249374; TopNews, Bang Phli: topnews.co.th
• CDC Floods: cdc.gov/floods; WHO: fact sheets; Department of Disease Control: ddc.moph.go.th