Watthana and the late-September 2026 rain: what the reports say

Here is what we know about Watthana itself:

• According to Thai PBS, on 29 September 2026 the DDPM declared three Watthana subdistricts, Khlong Tan Nuea, Khlong Toei Nuea and Phra Khanong Nuea, as flood assistance zones, with the hazard dated from 25 September 2026.
• In the sources we checked, there was no street-by-street water level report for Watthana. We therefore do not state any depth, and we do not claim that a particular soi was flooded to a particular level.

For Bangkok as a whole, Thai PBS and other outlets reported that rain on 25 to 26 September 2026 peaked at 210.0 mm in Chatuchak, 205.5 mm in Wang Thonglang and 203.5 mm in Saphan Sung, with more than 300 mm falling in roughly 48 hours. On 26 September all 50 districts were declared disaster areas. Reported waterlogging points rose from 43 at 18:30 on 25 September to 135 on 27 September, and on 29 September the DDPM listed assistance zones in 38 districts and 118 subdistricts. DDPM figures on 6 October 2026 put affected Bangkok households at about 329,000. These numbers change as the situation develops, so always check the latest official notices.

The picture for Watthana, then, is a district officially recognized as affected, where the impact most likely took the form of temporary rainwater pooling, drain backflow and lingering indoor dampness, rather than days of deep floodwater. Our ranking is built around that reality.

Flood points in Watthana District: what was reported and what was not

• Khlong Tan Nuea: listed as a flood assistance zone by the DDPM on 29 September 2026.
• Khlong Toei Nuea: on the same list.
• Phra Khanong Nuea: on the same list.
• Street or soi water depths: not found in the reports we used.

These three subdistricts cover the Sukhumvit, Ekkamai and Thong Lo area: a dense mix of condominiums, rental apartments, serviced apartments, hotels, restaurants, cafes, clinics, salons, office towers and detached houses on deep sois. Many buildings have basements, refuse rooms and pump rooms where rainwater and drain water can creep in and sit, even when the street dries within hours.

So after heavy rain in Watthana, check the low points inside buildings, not only the roads, and write down where water came in and for how long. That log helps both the cleaning crew and the spraying team.

Example case: a basement car park in a Thong Lo condo

Note: this is a typical scenario put together from situations that commonly follow heavy urban rain. It is not a statement from any specific customer and is not tied to a real building.

Pim manages the juristic person office of a mid-sized condo on a soi off Thong Lo. On the night of 25 September the rain kept falling for hours. The street outside had enough water that cars crawled through it, but what worried Pim was a call from security: the floor grates in the basement car park were pushing water up instead of draining it. Cloudy water with a sewer smell spread across the parking level and into the shared refuse room next door.

By morning most of the water was gone, leaving a thin film of mud on the floor, along the base of the walls and around the refuse room. The musty smell stayed. Residents complained that the basement lift smelled bad. A few days later the housekeeper noticed small black spots on a storeroom wall and behind a filing cabinet in the ground-floor office. Pim was not sure whether mopping with the usual floor cleaner was enough, and she worried about residents with small children or elderly parents.

Pim needed to know which germs to deal with first and in what order, which is why we put this ranking together.

How we ranked flood germs in Watthana District

This is WHD's editorial ranking. It is not an official ranking from any government agency, and it is not based on case statistics for Watthana. We do not have district-level patient numbers and we will not invent any. We weighed each germ on five criteria:

1. Fit with the setting: Watthana is high-rises, condos, restaurants and offices, and the main impacts were rain pooling, drain backflow and indoor humidity. Germs tied to those conditions rank higher.
2. How often flood guidance mentions it: how often WHO, the US CDC and Thailand's Department of Disease Control mention the germ or group in the context of floods, sewage or damp buildings.
3. Severity and who is at risk: germs that can cause serious illness in young children, older adults, pregnant women or people with chronic conditions get more weight.
4. Persistence: germs that survive longer on surfaces or in damp places rank above fragile ones. We describe this qualitatively only.
5. Ease of spread in crowded buildings: condos, offices and restaurants have many shared touch points such as lift buttons, handrails and door handles, so contact-spread germs get extra weight.

A lower rank does not mean a germ is harmless. If you or anyone in your household feels unwell, see a doctor. This article is not medical advice.

The ranking: 10 flood germs in Watthana District, 2026

No. 1: Mold in high-rises and basements, such as Aspergillus, Penicillium and Cladosporium

Why first: where water seeps in rather than floods deeply, mold is the fastest and most common problem. CDC and WHO both advise drying wet materials as quickly as possible, generally within 24 to 48 hours, to limit mold growth. Where it hides: basement storeroom walls, car park ceiling edges, behind built-in wardrobes, carpets, swollen gypsum board and cardboard boxes. Who is at risk: spores can trigger sneezing, coughing and eye irritation, and worsen asthma or allergies; people with weakened immunity should avoid heavily moldy rooms because Aspergillus can infect the lungs. Prevention: dry fast with fans and dehumidifiers, remove soaked materials that cannot dry, wear a mask and gloves, and never paint over mold. Spraying's role: after removal and wiping, spraying treats residual mold on surfaces; the WHD service information states CHEMGENE HLD4H covers fungi.

No. 2: Sewage bacteria from drain backflow, such as E. coli (Escherichia coli) and coliforms

Why second: when public drains fill up, water escapes at the lowest outlet: basement floor grates, ground-floor bathroom drains or restaurant floor channels. E. coli is the standard indicator of faecal contamination; where it is found, other gut germs may be present too. Where it hides: mud film on car park floors, refuse rooms, pump rooms, tile grout in ground-floor bathrooms, shop doorsteps, and trolley wheels and shoes that carry it into lifts. Who is at risk: some types cause diarrhoea, cramps and vomiting, which can be serious in small children and older adults; cleaners working without gloves face higher exposure. Prevention: boots and gloves, wash mud off with clean water and detergent first, wash hands with soap, keep children and pets away. Spraying's role: E. coli is a bacterium, and the product information says CHEMGENE HLD4H covers bacteria, but WHD's pages do not show a specific E. coli test result; ask WHD if you need that data. WHO and CDC advise cleaning flood-contaminated surfaces first, then disinfecting.

No. 3: Legionella pneumophila in high-rise water systems and cooling towers

Why third: Watthana has many towers, hotels and offices using cooling towers and large water tanks. When systems are shut down or sediment enters a tank, warm stagnant water suits Legionella, which spreads by breathing in contaminated droplets, not by normal drinking. Where it hides: rooftop cooling towers, idle tanks, showers in unused rooms, fountains and spa pools. Who is at risk: it can cause Legionnaires' disease, a pneumonia, or milder Pontiac fever; older adults, smokers and people with lung disease or weak immunity are most at risk. Prevention: building engineers should clean cooling towers on schedule, flush idle pipes and have specialists treat tanks. Spraying's role: surface spraying does not treat water inside pipes or cooling towers; that is a job for water-system contractors. WHD's pages show no Legionella-specific test; ask directly if needed.

No. 4: Norovirus in restaurants, cafes and shared kitchens

Why fourth: When drains back up into kitchens, or staff walk through pooled water and then handle food, the chance of gut germs reaching food rises. Norovirus is a leading cause of sudden vomiting and diarrhoea, spreads very easily and resists some common cleaners. Where it hides: chopping boards, prep counters, fridge handles, taps, staff toilets and kitchen floors near drains. Who is at risk: anyone, but young children and older adults can become dehydrated; see a doctor if vomiting or diarrhoea is heavy. Prevention: discard food that touched floodwater, clean and disinfect boards, knives and prep surfaces, keep sick staff home and wash hands often. Spraying's role: norovirus is listed among the organisms the CHEMGENE HLD4H product information says it covers. In restaurants, spray after the kitchen is washed and food is put away, and follow the technician's re-entry time.

No. 5: Pseudomonas aeruginosa in drains, bathrooms and always-wet spots

Why fifth: Pseudomonas thrives in water and damp places. After heavy rain leaves water standing in building drains longer than usual, it can multiply, and Watthana has many clinics, spas and gyms. Where it hides: shower floor drains, basins, sponges, damp towels and equipment reservoirs. Who is at risk: healthy people may get itchy skin rashes; people with wounds or weak immunity can develop more serious infections. Prevention: scrub drains and basins, replace soaked sponges and cloths, ventilate bathrooms and cover cuts. Spraying's role: it is a bacterium, within the group the product says it covers, but no specific test is shown online. Spraying works best after slimy biofilm is scrubbed away, because biofilm shields germs.

No. 6: Respiratory viruses in offices and condos: influenza (including H1N1), RSV and SARS-CoV-2

Why sixth: these viruses do not come with floodwater, but during heavy rain and cleanup people spend longer in closed rooms, crowd into lifts and are tired, which helps them spread. Where they hide: lift buttons, door handles, handrails, meeting tables, remote controls, fingerprint scanners and lobby counters. Who is at risk: RSV can be serious in infants and older adults; influenza and COVID-19 in people with chronic illness. Anyone short of breath should see a doctor. Prevention: handwashing, masks when sick, staying home when ill, ventilation and wiping shared touch points. Spraying's role: according to WHD's service and product information, SARS-CoV-2, RSV, H1N1 and H5N1 are on the list of covered organisms, so spraying shared areas after a big clean helps on the day everyone returns.

No. 7: Leptospira, the cause of leptospirosis, in sois, refuse rooms and ground-floor shops

Why seventh: nationally, leptospirosis is the disease the Department of Disease Control warns about most after floods. With no deep street flooding reported in Watthana, long wading is less likely here, so we place it mid-table. Still, restaurant-dense areas have rats in refuse rooms and drains, and heavy rain flushes them out. Where it hides: pooled water behind restaurants, refuse rooms, freshly drained car parks and mud along curbs. Who is at risk: waste collectors, housekeepers, kitchen staff and anyone wading. Symptoms include sudden high fever, headache, calf pain and red eyes; see a doctor and mention water exposure. Prevention: no bare feet in pooled water, boots, waterproof plasters, sealed rubbish and washing feet with soap. Spraying's role: Leptospira is a bacterium; WHD shows no specific test, but cleaning rat-affected areas and then disinfecting surfaces follows public health advice. Ask WHD for test data if needed.

No. 8: Salmonella in kitchens hit by drain backflow

Why eighth: Salmonella is linked to raw eggs, poultry and cross-contamination. Drain backflow or a fridge losing power during the storm can spoil and contaminate stored food. Where it hides: fridges that lost power, ingredients stored on the floor, shared boards and knives, and kitchen floors near drains. Who is at risk: diarrhoea, fever and cramps, more serious in children, older adults, pregnant women and people with weak immunity. Prevention: when in doubt, throw it out; separate raw and cooked boards; cook thoroughly; clean fridges before restocking. Spraying's role: Salmonella is on the CHEMGENE HLD4H product list. Spray after degreasing and removing mud, with all food removed.

No. 9: Staphylococcus aureus and wound germs during cleanup

Why ninth: hauling wet items, pulling down ceilings and moving furniture causes small cuts. Skin and environmental bacteria such as Staphylococcus aureus can infect them; soil-contaminated wounds also carry a tetanus (Clostridium tetani) risk, so ask a doctor about vaccination. Where it hides: shared tools, reused wet cloth gloves, staff towels and frequently touched surfaces. Who is at risk: anyone with a cut; people with diabetes and older adults heal more slowly. Redness, swelling, heat, pus or fever need medical care. Prevention: thick gloves, closed shoes, wash cuts at once and keep them covered. Spraying's role: it is a bacterium within the covered group, with no specific test shown online; spraying reduces germs on surfaces but does not treat wounds.

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

Why tenth: people who wade through pooled water or wear wet shoes all day get foot and skin problems, known locally as "water-bitten feet". Where it hides: shared shower floors, staff locker rooms, wet mats, damp shoes and shared towels. Who is at risk: itching, peeling and soggy skin between toes. Prevention: wash and dry feet, change socks, dry shoes, do not share towels. Spraying's role: the product is stated to cover fungi in general; there is no specific test for these organisms online. Spraying locker rooms and showers after scrubbing reduces surface build-up.

Why soap, floor cleaner or bleach alone falls short

Floor cleaners are made to lift dirt and leave a scent, not to deal with sewage contamination. Bleach works on some hard surfaces at the right dilution, but it can corrode metal and fade materials, smells strongly in closed rooms, and must never be mixed with ammonia or acid cleaners. Mops miss lower walls, cabinet edges and pipe gaps, and air fresheners only mask the musty smell that signals moisture and mold.

WHO and CDC advise removing water and mud, cleaning with water and detergent, drying, and then disinfecting surfaces that touched floodwater. Professional spraying is the step that completes that sequence; it never replaces washing.

WHD post-flood disinfection spraying in Watthana District

World Health Disinfection (WHD) is based in Bangkok (Bang Khae, 10160) and provides a disinfection spraying service for homes, condos, offices, shops and other buildings. According to the service information, trained technicians spray and/or ULV-fog (Ultra Low Volume fine mist) using CHEMGENE HLD4H, a medical-grade disinfectant from the UK containing Benzalkonium Chloride and Didecyldimethylammonium Chloride. The service page describes it as broad-spectrum against viruses, bacteria and fungi, lists organisms including COVID-19, RSV, H1N1, H5N1 and hand-foot-mouth virus, and claims 99.99%. It lists the Department of Medical Sciences, Mahidol University, NHS England and EN 14476:2013+A2:2019, and names hospitals, schools, malls, airports, offices, airlines, banks and residential buildings among its customers.

WHD serves Watthana by appointment. We have no branch in the district and do not promise same-day visits. Call 065-556-6294 or add LINE @whd268.

How the service works

1. Survey: identify where water entered, where drains backed up and where mold or odour appears.
2. Prepare: the owner or cleaning crew removes mud and water, washes surfaces, removes damaged materials, dries the area and puts away food and personal items.
3. Zone: people and pets leave each zone while it is sprayed.
4. Spray: technicians spray or ULV-fog floors, lower walls, door edges, lifts and plant rooms.
5. Re-enter: per the service information, wait about 30 minutes, then use the space normally, following the re-entry time the technician gives on site.

We do not claim the product leaves no residue; tell the technician in advance about anyone sensitive to chemicals. For musty air in closed rooms, the residential ozone disinfection service can complement spraying. Current promotion: a free CHEMGENE spray bottle and WELLGIENIC wet tissues with the service, and tax invoices are available.

10 reasons Watthana buildings should spray after heavy rain

1. Low points such as basement car parks and refuse rooms take drain backflow first, and technicians focus there.
2. Closed, humid buildings favor mold; spraying after drying treats surface mold.
3. Shared touch points are everywhere, and the spraying service covers them.
4. Restaurants need confidence that kitchens are washed and disinfected before reopening.
5. Trained technicians know the right sequence and safety steps.
6. A medical-grade UK disinfectant, according to the product information.
7. ULV fogging reaches corners a mop misses.
8. Spaces are usable after about 30 minutes, per the service information.
9. Published certifications and standards, plus tax invoices. See details.
10. Juristic offices and owners can tell residents and customers the space has been cleaned and disinfected.

Before and after spraying

Checklist for Watthana condos, shops and offices

Before spraying

• Cut power to wet zones and have an electrician check before reconnecting.
• Wear boots, gloves and a mask.
• Remove mud and rubbish, wash floors and lower walls, scrub drain channels.
• Remove soaked materials that cannot dry, then dry the space quickly.
• Discard food that touched floodwater or sat in a fridge without power.
• Put away food, dishes, toys and personal items; move pets out.

After spraying

• Re-enter at the time the technician gives (about 30 minutes per the service information).
• Ventilate and rinse food-prep surfaces as advised.
• Watch for returning damp and fix leaks at the source.
• See a doctor for fever, diarrhoea, calf pain or breathing trouble.
• Recheck for mold over the following weeks.

FAQ: flood germs in Watthana District

How deep was the water in Watthana in 2026? We found no street-level depth reports. What is confirmed is the DDPM listing of Khlong Tan Nuea, Khlong Toei Nuea and Phra Khanong Nuea as assistance zones on 29 September 2026, with the hazard dated from 25 September.

Our condo only had water in the basement car park. Do we need spraying? If it was drain backflow, it may carry sewage. Clean first, then spray where water entered, including refuse rooms and basement lifts. The whole building is not necessary if other floors stayed dry.

Does the disinfectant cover every germ listed? The product and service information lists organisms such as COVID-19, RSV, H1N1, norovirus, Salmonella, bacteria in general and fungi. For others here, such as E. coli, Leptospira, Legionella or Pseudomonas, no specific result is shown online; ask WHD for test data.

Do we have to leave during spraying? Yes, people and pets leave the zone. Re-enter after about 30 minutes or as the technician says.

Does WHD have a Watthana branch? No. WHD is in Bang Khae and serves Watthana by appointment, with no same-day guarantee.

The rain has stopped in Watthana. Let WHD finish the job.

Once mud is out and the space is dry, our technicians can spray car parks, refuse rooms, kitchens and shared touch points.

Book disinfection spraying

Call 065-556-6294 · LINE @whd268

Related services and references

• WHD disinfection spraying service
• WHD residential ozone disinfection
• Thai PBS, DDPM assistance zones (29 Sep 2026): thaipbs.or.th/news/content/558867
• Thai PBS, rainfall 25 to 26 Sep 2026: thaipbs.or.th/news/content/558661
• Thai PBS, waterlogging points 27 Sep 2026: thaipbs.or.th/news/content/558668
• Naewna, waterlogging points 25 Sep 2026: naewna.com/n/bkk/81721
• Bangkok Biz News, DDPM figures 6 Oct 2026: bangkokbiznews.com/news/news-update/1255155
• WHO fact sheets: who.int/news-room/fact-sheets
• CDC floods: cdc.gov/floods
• Department of Disease Control, Thailand: ddc.moph.go.th