Last updated: 3 Oct 2026 | 16 Views |
Example case: a typical scenario in the Sena Nikhom area
Noi manages a four-storey, thirty-room dormitory that her mother built twenty years ago in a lane off Sena Nikhom Road. Almost all the tenants are students and young workers looking for an affordable room with easy access to Phahon Yothin Road and Kasetsart University. The ground floor holds six rooms, a laundry room with four coin-operated machines and a corner with a drinking-water vending machine.
On the night of 25 September 2026, the rain kept falling until the water on Sena Nikhom Road rose higher and higher. Noi says that in past floods the water covered only parts of the road, and tenants could walk around to a dry stretch. This time there was no way around it, because the whole road was under water. Students heading to class or part-time jobs had to take their shoes off and wade out to the main road, then wade back in the evening and climb the stairs without washing their feet. The ground-floor laundry room became the place everyone stopped to rinse their legs before going up.
When the water finally drained away, Noi hired people to shovel mud out of the ground-floor rooms and laundry. But the smell that lingered in the stairwell led several tenants to ask about moving out. Two students had diarrhoea in the same week, another developed an inflamed wound on the foot after wading, and in a ground-floor room left locked while its tenant went home upcountry, black spots had appeared in the wall corner behind the wardrobe. The question Noi heard most often was simple: is the dorm safe yet?
This article is written for dormitory and rental-room owners, restaurants, laundries and families living around Sena Nikhom Road, which news reports said flooded along its entire length. We look at where the water was, which germs matter most in buildings full of young people living close together, and where post-flood disinfection spraying in the Sena Nikhom area by World Health Disinfection (WHD) fits into the recovery.
According to news reports, Bangkok received roughly 300 mm of rain in about 48 hours between 24 and 27 September 2026. The Bangkok Metropolitan Administration declared all 50 districts a disaster zone on 26 September 2026, and the Department of Disaster Prevention and Mitigation reported that, as of 2 October 2026, around 329,000 Bangkok households had been affected.
A Thai PBS report on 29 September 2026, which compiled road water levels at 13:19 and a list of flood points across Bangkok, included these entries for the Sena Nikhom area:
For people who live here, "flooded along its whole length" means every lane off Sena Nikhom Road was affected at the same time. There was no dry route out, so everyone who had to come and go waded, and water flowing from one lane ran on into the next, spreading dirt from drains, restaurants and rubbish points across the whole neighbourhood.
Note: the report did not give a depth for Sena Nikhom Road, so this article does not give one. Water levels inside each building depend on that building's floor level.
Sena Nikhom is not a typical housing-estate neighbourhood. Because it sits close to Kasetsart University and the rail line on Phahon Yothin Road, it is packed with dormitories and rental rooms, student-priced eateries, coffee shops, laundries, convenience stores, print shops and motorbike-taxi stands at nearly every lane entrance. Deeper in, older wooden houses and townhouses are still home to long-established families.
When the whole road floods, three factors push the risk up. First, the number of people wading every day is very high: students, workers and vendors. Second, dorms and rental buildings often share bathrooms, laundries and stairs, so germs carried in on one person's feet reach others easily. Third, many eateries rush to reopen the moment the water drops because they have lost days of income, and some may not yet have disinfected their kitchens thoroughly.
The WHO and the CDC advise cleaning and drying out as quickly as possible, generally within 24 to 48 hours, to limit mould. In rented rooms whose tenants went home upcountry and left them locked for days, mould usually gets there before anyone else does.
In a neighbourhood full of budget eateries, Salmonella deserves top priority. It causes fever, stomach pain, diarrhoea and vomiting, and spreads from contaminated surfaces into food. When a restaurant kitchen has been under water, freezers have lost power and chopping boards or basins have soaked in floodwater, germs can persist even when utensils look clean. Owners should throw out every ingredient that touched the water, wash all equipment with clean water and dish soap, then disinfect food-prep surfaces, kitchen floors and lower walls.
Many older dorms in the lanes off Sena Nikhom still have a shared bathroom on each floor. When floodwater stops drains and septic tanks from emptying, sewage can push back up through floor drains in ground-floor bathrooms. Faecal bacteria then cling to floors, basins, taps and door handles, causing diarrhoea that passes from tenant to tenant.
Norovirus causes sudden vomiting and diarrhoea and spreads very easily through hands and surfaces. In dorms where students share food, use the same microwave and fridge, or eat together in one room, one case can become several within days. Rotavirus is common in young children, an important risk group for families living deeper in the lanes.
When the whole road floods, almost everyone has to wade, some several times a day, so the risk of leptospirosis is higher than in areas that flood in patches. The bacteria come from rat urine in the water and enter through cuts, scrapes or skin softened by long soaking. See a doctor urgently for sudden high fever, headache, muscle pain especially in the calves, or red eyes within about one to two weeks of wading, and tell the doctor about the flood exposure. This matters most for motorbike-taxi riders, delivery riders and students with foot wounds. Disinfection spraying reduces germs on surfaces inside buildings but cannot replace medical treatment.
Ground-floor rooms locked up while tenants went home during the flood are where mould grows best: stuffy, damp and without airflow. Black mould typically starts in wall corners behind wardrobes, on wooden bed frames, under mattresses and around window frames. Spores can cause coughing, sneezing and a blocked nose, and trigger asthma or allergies. Tenants who return to a strong musty smell should open windows before moving back in and ask the owner to inspect.
When people stay longer in closed rooms after a flood, respiratory viruses such as RSV and influenza spread more easily, and families with young children in the lanes should watch for hand, foot and mouth disease. According to the WHD service information, the disinfectant used is listed as covering RSV, H1N1 and hand, foot and mouth disease virus.
Besides children, older adults, pregnant women and people with chronic illness, this area has its own vulnerable groups: students with foot wounds who still had to wade to class, cooks working in kitchens that have only just dried out, dorm cleaners scrubbing shared bathrooms, and older residents of wooden houses whose floors sit below road level.
Health: illness in a dorm rarely stops with one person. Diarrhoea passed between tenants can mean students missing classes or exams and workers taking sick leave.
Income: nervous tenants may leave mid-contract, empty rooms that smell musty are harder to let, and a restaurant where a customer gets sick even once may lose that customer for good.
Workload: dorm owners answer tenants' questions daily, clean shared bathrooms again and again, and keep checking rooms whose tenants have not yet returned.
Online reputation: students and young workers review dorms and eateries in online groups. A single post saying a dorm smells after the flood, or that a shop made someone ill, can hit income for months.
Rinsing shared bathrooms with plain water and reopening them: water shifts mud but does not reduce the germs clinging to taps, handles and basins.
Mixing cleaning products: some people mix bleach with toilet cleaner to make it "stronger", which is very dangerous because it produces gases that damage the airways, especially in small, poorly ventilated bathrooms.
Reopening an eatery without disinfecting the kitchen: a spotless front table does not mean the kitchen behind it is safe. The floor under counters, the wall behind the stove and kitchen drains are where germs build up.
Locking a rented room and spraying air freshener: the fragrance hides the smell for a while, but the mould behind the wardrobe keeps growing.
One mop for every room: a single mop used for bathrooms, corridors and the laundry spreads germs throughout the building.
World Health Disinfection (WHD) provides a disinfection spraying service for dormitories, apartments, rented rooms, restaurants, shops, offices and homes. According to the service information, trained technicians spray disinfectant and/or apply a ULV (Ultra Low Volume) fine mist. The very fine droplets reach tight spaces such as shared bathrooms, gaps behind washing machines, under kitchen counters and the corners of rented rooms more evenly than wiping by hand.
The disinfectant is CHEMGENE HLD4H, a medical-grade disinfectant from the United Kingdom containing Benzalkonium Chloride and Didecyldimethylammonium Chloride. The service information lists coverage of viruses, bacteria and fungi, including COVID-19, RSV, H1N1, H5N1 and hand, foot and mouth disease virus, with a stated efficacy of 99.99%.
The service page lists approvals and references from the Department of Medical Sciences, Mahidol University, NHS England and the EN 14476:2013+A2:2019 standard, along with customers such as hospitals, schools, malls, airports, offices, airlines, banks and residential buildings.
The right order: remove mud, wash, wipe and dry first, then disinfect. Spraying does not replace cleaning. During application, tenants, restaurant staff and pets must leave the zone being sprayed and return at the time the technicians give. Restaurants must put away or tightly cover food, ingredients and utensils before spraying.
According to the service information, customers receive a CHEMGENE spray bottle and WELLGIENIC wet tissues for ongoing care of touch points. Dorm owners can leave them in the laundry or stairwell, restaurants can use them on menus and tables, and a tax invoice is available.
An illustrative example to explain the process, not a verified customer review.
Uncle Piak and Auntie Nid have run a boat-noodle shop from a single shophouse unit on Sena Nikhom Road for more than ten years. Their regulars are students and workers walking past on their way to the train. While the whole road was flooded, the shop had to close for several days. Water covered the shop floor and the kitchen at the back, the meatball freezer lost power, and the stockpot that sat on the floor was surrounded by water.
When the water receded, Uncle Piak threw out everything in the freezer, rewashed every pot, bowl, pair of chopsticks and chopping board, and hired help to scrub the kitchen floor and clear the drain. Auntie Nid was still uneasy, having heard customers complain that someone got sick at a nearby shop that reopened early. So they asked WHD to spray the shop front, kitchen and storeroom before reopening.
The team came one afternoon while the shop was still shut and asked Uncle Piak to put all bowls, chopsticks and condiments in closed cupboards. They sprayed the kitchen floor, the wall behind the stove, under the sink, table legs and customer chairs, waited about 30 minutes as per the service information, then raised the roller shutter to ventilate. Uncle Piak rewashed the food-contact utensils as advised. The shop reopened the next day, Auntie Nid used the CHEMGENE spray bottle on tables and menus between customers, and they put up a small sign saying the shop had been cleaned and disinfected after the flood.
Q: Only the ground floor of our dorm flooded. Do upper floors need spraying too?
A: Floors the water reached definitely need it. For upper floors, consider the stairs, handrails, corridors and shared bathrooms, since that is the route tenants carry floodwater germs upstairs. The team can help set the scope.
Q: How long do tenants need to stay out?
A: Stay out of the sprayed zone during application. According to the service information, wait about 30 minutes afterwards, then return at the time the technicians give.
Q: Can a restaurant open straight after spraying?
A: You can use the space when the technicians say so. For surfaces and utensils that touch food directly, follow the team's guidance.
Q: Can spraying replace cleaning the bathroom?
A: No. Remove grime first; spraying comes after cleaning.
Q: Is there no residue afterwards?
A: We do not claim that. Follow the technicians' advice on re-entry time.
Q: A student's foot wound became inflamed after wading. Will spraying help?
A: Spraying reduces germs on building surfaces; it does not treat wounds. Anyone with an inflamed wound or fever after wading must see a doctor.
Dorms, rented rooms, restaurants, shops and homes in the lanes off Sena Nikhom Road can book WHD Chemgene disinfection spraying today.
Book Disinfection in Sena Nikhom
Call 065-556-6294 · LINE @whd268
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