A Story from the Field: The Tenant Group Chat That Went Quiet

Auntie Chan is sixty and owns a four-storey, fifty-room women's dormitory down a side street in Bang Pu, in Mueang Samut Prakan district, a short ride from the industrial estate. Almost all of her tenants are women who work at nearby electronics, food-processing and auto-parts factories. Many work night shifts. Some come from provinces in the north and northeast, and several rooms are rented by workers from neighbouring countries.

During the 2026 floods, water rose about half a metre on the ground floor and stayed for days. Twelve ground-floor rooms, the women's shared bathroom downstairs, the coin-operated laundry room and the entrance lobby were all underwater. Ground-floor tenants moved in with friends for a while, and tenants upstairs waded out to work every morning.

When the water receded, Auntie Chan hired workers to shovel out the mud and wash the floors. What followed surprised her. A musty smell drifted up the stairwell all the way to the third floor. The shared bathroom smelled of drains, and black lines appeared along the tile grout. Particleboard wardrobes in the ground-floor rooms swelled and grew green spots of mold. Curtains smelled sour. Tenants complained that clothes hanging in their wardrobes smelled stale, and that colleagues at work had noticed.

The tenants' LINE group, usually busy with notices about parcels and water bills, started to fill with short messages: "I would like to move out at the end of the month." Two, then three rooms. Meanwhile, a newer dormitory one street over put up a banner saying "Clean rooms, ready to move in." Auntie Chan realised that washing the floors was not enough for a building where dozens of women share bathrooms and live day to day in small rooms.

She also understood something else. Her tenants were not being difficult. They work long hours on production lines, often standing for an entire shift, and their small room is the only place they have to rest. When that room smells of mud and the bathroom down the hall makes them uneasy, moving to a cleaner building is a reasonable choice. If she wanted them to stay, the building had to feel genuinely clean again, not just look clean, and tenants had to see that the owner was taking the problem seriously.

Why a Women's Dormitory Needs Extra Care After a Flood

A dormitory is not like a single family home. Many people share the same spaces: bathrooms, corridors, stairs, laundry rooms and drying areas. If germs or mold remain in even one shared space, the problem reaches everyone quickly.

• Shared bathrooms. This is what tenants worry about most. Floodwater that backs up through drains can bring sewage with it. Grout lines, the underside of shelves and the area around floor drains collect contamination. Many women simply do not feel comfortable using a bathroom that still smells and shows stains, and they are right to be cautious.
• Wardrobes and bedding in rooms. Small dormitory rooms are usually furnished with particleboard wardrobes, thin mattresses and fabric curtains, all of which soak up water and grow mold easily. Clothes stored inside pick up the smell.
• Laundry and drying areas. These spaces are damp even in normal times. After a flood they stay wet for much longer. Any washing machine that was submerged needs to be checked by a technician before it is used again.
• Corridors and stairwells. The stairwell acts like a chimney. Musty air from the ground floor rises through it, so rooms upstairs that never touched floodwater start to smell as well.
• Shift workers sleeping in the daytime. Many tenants sleep during the day with curtains closed and little airflow. A damp room makes that sleep worse, and people wake up congested and tired before a long shift.

The Real Costs an Owner Has to Consider

Tenant health. Floodwater is often contaminated with sewage, bacteria such as E. coli, and the bacteria that cause leptospirosis. Traces can remain on floors and lower walls. Mold spores in damp rooms can trigger allergies, asthma, a blocked nose, sneezing and coughing. Tenants who keep falling ill are unlikely to renew.

Income. Every empty room is income lost every month. If several tenants leave at once and the building gets a reputation for "still smelling musty after the flood," finding new tenants becomes much harder, especially when newer buildings nearby are competing for the same workers.

Reputation among factory workers. Dormitories near industrial estates fill mostly by word of mouth inside factories and through workers' social media groups. A handful of negative posts can affect occupancy for a long time.

Building assets. Particleboard wardrobes, wooden doors, mattresses and curtains that are left to grow mold eventually have to be replaced completely. That is usually far more expensive than dealing with the problem early.

The owner's time and energy. Owners who manage the building themselves while answering tenant questions every day rarely have the time to clean each room thoroughly, one by one, to a standard that removes both the germs and the smell.

Why the Usual Clean-Up Is Not Enough

• Pouring bleach over the bathroom. It helps on smooth tiles, but it does not penetrate grout or concrete walls that absorbed water. The sharp smell lingers in a bathroom with poor ventilation, and mixing different cleaning products can produce dangerous gases.
• Running fans down the corridor. Fans dry the floor faster, but they also push mold spores up the stairwell to the floors above.
• Charcoal bags and odor blocks. These can help in a small cupboard, but they are nowhere near enough for an entire building, and they do not disinfect anything.
• Repainting so the rooms look clean. If the walls are still damp, mold will lift the new paint within a few weeks, and the first new tenant to move in will see it.
• Asking each tenant to clean her own room. Results vary from room to room, and nobody takes full responsibility for the shared areas, which are exactly where the problem is worst.

The Solution: Whole-Building Recovery with WHD Disinfection Fogging and Ozone Treatment

World Health Disinfection (WHD) provides disinfection fogging and ozone treatment for residential buildings after floods, including dormitories, apartments and staff housing. We plan for the whole building, not just one room at a time.

Disinfection fogging with CHEMGENE HLD4H. We use CHEMGENE HLD4H, a professional-grade disinfectant, applied with ULV equipment that turns it into a very fine mist. The mist reaches bathroom grout, the areas around drains, corridor corners, stair rails, door handles and the lower walls of every room that took on water.

Ozone treatment for rooms, wardrobes and shared spaces. Ozone spreads through the whole room, into wardrobes left open, under beds and into the gaps behind furniture. It helps reduce airborne mold spores and breaks down the molecules behind musty, drain-like and muddy odors, including the smell that travels up the stairwell.

How We Work in a Dormitory

1. Building survey. We check how high the water rose, how many rooms were affected, the condition of the shared bathroom and laundry room, and the route the smell takes upstairs.
2. Planning with the owner. We split the work by floor or by zone, so tenants upstairs can keep living normally, and we schedule around night-shift workers' sleeping hours as much as possible.
3. Sorting advice. Mattresses, curtains and particleboard wardrobes that swelled in floodwater should usually be discarded or replaced. Tenants' clothes should be washed before going back into wardrobes.
4. ULV disinfection fogging. We start with the shared bathroom, laundry room, entrance lobby and corridors, then the ground-floor rooms.
5. Ozone treatment. Each area is closed off and treated for a time matched to its size. Dose and duration are controlled, and sensitive electronics are covered or moved out beforehand.
6. Ventilation and re-check. Doors and windows are opened so ozone can break down into oxygen. We re-check odors and mold spots and tell the owner when tenants can return.

How to Communicate with Tenants So They Feel Confident

• Announce the schedule early. Post in the LINE group and put notices on doors with the date, time, floors being treated and when rooms can be re-entered. If you have tenants from neighbouring countries, add a short translation so everyone understands.
• Respect privacy. Ask tenants to put away personal items and valuables before the service day. The owner or building caretaker should accompany the team whenever a private room is entered.
• Share the results clearly. After the work, tell the group which areas have been disinfected and ozone-treated, and remind tenants to wash any clothes that still smell before putting them back.
• Set temporary house rules. For example, open windows during the day, do not dry wet laundry inside rooms, and report any new mold spot to the caretaker immediately.
• Keep shared touch points clean. Wipe door handles, stair rails and bathroom taps daily with CHEMGENE HLD4H spray.

Checklist: High-Risk Spots in a Women's Dormitory After a Flood

• ☐ Floor and wall grout in the shared bathroom, around toilets and floor drains
• ☐ Shelves for toiletries in the bathroom and baskets tenants leave behind
• ☐ Particleboard wardrobes, the back panel against the wall, and the floor under beds
• ☐ Curtains, blinds and mattresses in ground-floor rooms
• ☐ The laundry room, drying racks and rooftop drying area tenants share
• ☐ The stairwell and corridors where smells rise to upper floors
• ☐ Lockers, shoe cabinets and shoe racks at the entrance
• ☐ The caretaker's room and storerooms that are easy to forget

These are the places our team pays special attention to. Owners can walk through them quickly before booking, which makes planning faster and helps estimate how many zones the work should be split into.

Why the Smell Travels Upstairs, and Why That Matters

Owners are often puzzled when tenants on the third floor complain about a smell, even though water never came close to their rooms. The explanation is simple. Warm, humid air rises. In a typical dormitory, the open stairwell and the corridors connect every floor, and the ground floor, where the mud, wet walls and soaked furniture are, becomes the source of that warm, damp air. As it rises, it carries the musty odor and some of the airborne mold spores with it.

Plumbing adds a second path. If drains in the ground-floor bathroom were flooded and are not flowing freely, or if the water seals in floor traps have dried out, sewer gas can rise through the shared pipes and escape into bathrooms upstairs. That is why we always look at drains and traps during the survey, and why treating only the rooms that were flooded rarely solves a whole-building smell problem.

The practical lesson for owners is that the ground floor and the stairwell should be treated as one system. Fix the source, treat the path, and the upper floors usually improve at the same time.

A Week-by-Week Recovery Timeline for Dormitory Owners

Week 1: Clear and document. Shovel out mud, remove soaked mattresses, curtains and swollen particleboard, and photograph all damage before anything is thrown away. Open every window you safely can on the ground floor. Ask an electrician to check the wiring, sockets and the coin-operated washing machines before power is restored to those circuits. Post a short update in the tenants' group so people know the owner is acting.

Week 2: Disinfect and deodorize. Once the floors are clear and surfaces have started to dry, book disinfection fogging and ozone treatment. Start with the shared bathroom and laundry room, because tenants use them every day, then the lobby, corridors and stairwell, then the ground-floor rooms. Tell tenants exactly which zone is being treated on which day.

Week 3: Repair and refurnish. When walls are properly dry, repaint where needed and replace wardrobes, mattresses and curtains. Choosing moisture-resistant materials for the ground floor, such as plastic or metal shoe racks and washable curtains, makes future flood seasons easier.

Week 4 and beyond: Maintain. Keep a simple routine: daily wiping of shared touch points, weekly checks of grout and lower walls for new spots, and fast responses whenever a tenant reports a smell. Small, consistent habits are what keep tenants renewing their leases.

What Tenants Can Do in Their Own Rooms

Owners can share these simple tips with tenants once the building has been treated. They help the results last longer and give tenants a sense of control over their own space.

• Wash and fully dry clothes before storing them. Damp clothes inside a closed wardrobe are one of the fastest ways to bring the smell back.
• Leave wardrobe doors open for a while each day. A little airflow inside the wardrobe makes a big difference in humid weather.
• Do not dry laundry inside the room. Use the shared drying area or rooftop instead, so moisture does not build up where you sleep.
• Open the window when you are awake. Night-shift workers can open windows for an hour or two before or after sleeping.
• Report problems early. A small dark spot behind a wardrobe is easy to deal with this week, and much harder next month.

Planning Downtime Without Guesswork

Owners naturally want to know how long rooms will be out of use. The honest answer depends on the building: how many rooms took on water, how wet the walls still are, and how much furniture needs to be removed. During the survey, our team will explain how many zones the work can be divided into and roughly how long each zone needs for fogging, ozone treatment and ventilation. That lets owners plan which tenants need to step out, and when, without closing the whole building. Contact us by phone or LINE with the number of floors and affected rooms, and we can prepare a plan that fits your situation.

10 Reasons Dormitory Owners in Bang Pu Choose WHD

1. ULV disinfection fogging that reaches shared-bathroom grout and corridor corners.
2. We use CHEMGENE HLD4H, a professional-grade disinfectant.
3. Ozone treatment reduces musty odors in rooms, wardrobes and the stairwell.
4. A whole-building plan split by floor, so upstairs tenants can keep living there.
5. Scheduling that takes shift workers into account.
6. Controlled ozone dosing, with tenants' electronics covered before treatment.
7. Clear safety steps and a clear time for tenants to return.
8. Advice on which mattresses, curtains and furniture should be replaced.
9. A dust mite removal service for mattresses that can still be used.
10. A mosquito spraying service around buildings with standing water.

Before and After Dormitory Recovery

Customer Voice (Example Scenario)

"I thought washing the floors would be the end of it, but the smell just would not go away, and the girls complained every day. After the team disinfected the shared bathroom and ozone-treated the ground-floor rooms, the corridor smell dropped a lot. I posted the details in our group and the tenants felt much better about it. A couple of rooms that said they would move out decided to stay."

— Auntie Chan, women's dormitory owner in Bang Pu (example scenario)

Frequently Asked Questions

Q: Do all tenants have to leave the building?
A: Not necessarily. The team can work floor by floor or zone by zone. Tenants only need to leave the area being fogged or treated, and can return once it has been ventilated properly.

Q: Can you work during the day when some tenants are on night shift?
A: Yes, with planning. Night-shift tenants in the zone being treated will need to rest somewhere else for a few hours, or we can choose a time when those rooms are empty.

Q: Do clothes need to come out of the wardrobes?
A: Yes, ideally. Clothes that smell musty should be washed and dried properly, then put back once the room has been treated and ventilated.

Q: When can the shared bathroom be used again?
A: After disinfection and ventilation, as the team advises. Bathrooms are usually treated first so tenants can use them again as soon as possible.

Q: Can the coin-operated washing machines that were submerged be used?
A: They must be checked by an electrician or the machine operator before use. The laundry room itself can be disinfected and ozone-treated to reduce the musty smell.

Q: Should we treat rooms upstairs that were not flooded?
A: If tenants upstairs notice the musty smell, it usually comes from the ground floor through the stairwell or drains. Treating the source and the stairwell often solves it, and the team can advise during the survey whether specific upstairs rooms also need ozone treatment.

Q: Will tenants' TVs or computers be damaged?
A: The team controls the dose and treatment time and recommends covering or removing sensitive electronics beforehand.

Help Your Tenants Move Back with Confidence. Book WHD Today.

We serve dormitories, apartments and staff housing in Bang Pu, Thai Ban, Phraeksa and nearby areas of Mueang Samut Prakan.

View Disinfection Service – Click Here

Book Ozone Treatment – Click Here

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

Related Links

• Residential ozone disinfection
• Ozone treatment for odors and chemical residue
• Master Ozone Generator
• All articles
• External sources: WHO: Floods and health and Thailand Department of Health