A Story from the Field: The Same Key, a House He Barely Recognised

Uncle Somsak is a sixty-year-old retired civil servant. Besides his own home, he owns a two-storey townhouse in a housing estate off Phetkasem Road in Nong Khaem, Bangkok. For the past three years he has rented it to a young couple with a small child, and the monthly rent has become an important part of his retirement income.

During the 2026 floods, water in the soi rose to about forty centimetres inside the house and stayed for almost a week. The tenants took their child to relatives in another province. About ten days after the water receded, they sent Uncle Somsak a LINE message. They had found new jobs upcountry, wanted to end the lease and would not be coming back. The message ended with one short line: "Whatever is left in the house, you can deal with it, Uncle."

By the time Uncle Somsak unlocked the front door, the house had been shut for nearly four weeks. A wall of musty, rotten air hit him at once. A mattress leaning against the ground-floor wall was still damp and covered in green and black mold. The fabric sofa had a tide line where the water had soaked in. Bags of clothes piled in the corner had turned to a soggy mass. Cardboard boxes had collapsed. The rug was still holding water. On the painted walls of the ground floor, black mold had climbed in a band almost one metre high. Flies buzzed around the kitchen, cockroaches scattered from under the cabinets, and the smell had drifted all the way up to the bedrooms on the first floor.

"I don't know where to start," he told our team. "Can I throw their things away? Should I take photos first? And how long before anyone will want to rent a house like this again?" These are exactly the questions many landlords across flood-hit Bangkok are asking right now. The good news is that, handled in the right order, a house like this can be restored and let again without lingering smells or disputes.

Why Wet Belongings Left Behind Make Mold Spread So Much Faster

Mold after a flood is common, but a house where wet belongings have been left inside for weeks is a special case. The belongings themselves turn a manageable problem into a house-wide one.

• Wet items are a moisture source that never switches off. Mattresses, sofas, rugs and piles of clothing soak up a great deal of water. Shut inside a closed house, they slowly release that moisture into the air day after day, keeping humidity high long after the floodwater has gone.
• They are both a home and a food supply for mold. Fabric fibres, foam, paper and the fine silt carried in by floodwater are ideal food for mold. Once colonies establish themselves on these items, they release spores that settle on walls, door frames and the landlord's own furniture.
• An empty house never gets aired. A home where people live at least gets its doors and windows opened and its fans switched on. A rental the tenant has already left stays sealed until the owner arrives.
• Food and rubbish attract pests. Rice, dry food that got wet and kitchen rubbish draw flies, cockroaches and rats, which add a serious hygiene problem on top of the mold.

The longer this combination sits, the further the mold spreads, and the more of the house needs treatment rather than just the items themselves.

What It Means for a Landlord

Health. Whoever goes in to clear a house like this is exposed to a heavy load of mold spores, which can cause allergy symptoms, coughing, chest tightness and asthma attacks. Mud and flood residue can carry bacteria from sewage, leading to diarrhoea and skin infections. Where there are signs of rats, there is also a risk of leptospirosis, which can enter the body through cuts and broken skin. Always wear gloves, rubber boots and a mask that filters fine particles, and be especially careful if you are an older landlord doing the work yourself.

Income. Every month the house cannot be let is rent you do not receive. The longer the mold is left to spread, the bigger the repair job becomes and the longer it takes before the house is ready for a new tenant.

Reputation of the property. Prospective tenants notice a musty smell and mold stains the moment they walk in. A house with even a faint odour is often negotiated down or crossed off the list altogether. In an estate where several houses were flooded, the homes that smell clean and look well cared for are the ones that get rented first.

Your relationship with the tenant. A flood is stressful for everyone. A clear, fair process for handling belongings and the deposit protects the relationship and avoids disputes that drag on for months.

Before You Throw Anything Away: Document Everything and Agree with the Tenant

This is the step many landlords skip because they are eager to start cleaning. Doing it in the right order prevents problems later. (This section is general guidance, not legal advice. If you are unsure about your rights or obligations, consult a legal professional.)

1. Photograph and video every room before touching anything. Show the waterline on the walls, the items left behind, where mold has grown and the condition of any furniture that belongs to you. These records help when talking to the tenant and, if your policy covers flood damage, when you contact your insurer.
2. Confirm with the tenant in writing. Even if the tenant has said "you can deal with it", send a list of the remaining items with photos and ask them to confirm by message. Give a clear date. They may want to keep documents, photos or items with sentimental value.
3. Review the lease and discuss the deposit openly. Flood damage is something neither side intended. Talking it through with facts and photos makes it far easier to reach an agreement both of you feel is fair.
4. Keep every receipt. Rubbish removal, repairs and cleaning services should all be documented, both for any insurance claim and for settling up with the tenant.

What to Throw Away and What You May Be Able to Keep

• Usually discard: mattresses, pillows, fabric sofas with soaked foam, rugs and underlay that sat in water for days, cardboard boxes, and any food or rice that got wet. These items tend to hold contamination deep inside and cannot be cleaned reliably.
• Often salvageable after cleaning: solid wood furniture that has not swollen, metal tables, plastic chairs, ceramic dishes and metal cookware. Wash them thoroughly and let them dry completely.
• Have a technician check: appliances that were submerged, the fridge, the washing machine, and ground-floor sockets and switches. Do not plug anything in to test it until an electrician has inspected the wiring.
• Bulky waste: ask the district office about bulky waste collection after the flood. Do not leave a pile outside the house for long, because it quickly becomes a breeding ground for germs, flies and rats.

Why the Usual Landlord Shortcuts Are Not Enough

• Painting over the mold. It makes the house look fresh quickly, but if the walls are still damp and contaminated underneath, the paint will blister and the mold will be back within weeks. The new tenant is the one who discovers it, and the complaint comes back to you.
• Pouring bleach everywhere and locking up. The harsh smell lingers in a closed house, and bleach does nothing about spores floating in the air or hiding in door frames, under the staircase and behind built-in cabinets.
• Spraying air freshener before viewings. Fragrance masks the smell for an hour or two. Once a new tenant moves in, the musty odour returns within days.
• Leaving the doors and windows open and going home. Townhouses have limited cross-ventilation, and leaving an empty house open and unattended creates its own security risk.

The Solution: Disinfection Fogging and Ozone Treatment Before Handing Over to a New Tenant

Once the wet belongings are out and the house has started to dry, the next step is dealing with the germs and spores that remain in the building itself. The World Health Disinfection (WHD) team uses two complementary services.

Disinfection fogging service. We apply CHEMGENE HLD4H disinfectant with ULV fogging equipment. The ultra-fine mist reaches walls, floors, the space under the stairs, the inside of kitchen cabinets and corners that are hard to reach by hand, helping to deal with bacteria and mold on surfaces that were touched by floodwater.

Ozone treatment service. After fogging, the team closes up the house and runs an ozone treatment. Ozone gas spreads through both floors, helping to deal with airborne mold spores and breaking down the molecules behind musty, muddy and rotten odours that have soaked into the structure. The result is a house you can confidently show to prospective tenants.

Fogging handles the surfaces. Ozone handles the air and the smell. Together they cover what manual scrubbing usually misses.

How the WHD Team Works on a Rental Property

1. Survey and assessment. We review photos or visit the house, assess the extent of mold and odour, and plan the work with the owner, including timing around repairs and painting.
2. Clearing and mud advice. We advise what should be removed first, where mud needs washing out, and roughly how long the walls should be left to dry before treatment.
3. Fogging with CHEMGENE HLD4H. The ground floor, bathroom, kitchen, under the stairs and any areas with signs of rats or insects are treated thoroughly.
4. Whole-house ozone treatment. Doors and windows are closed, and the ozone dose is controlled to suit the size of the house. No people, pets or plants may be inside during this stage.
5. Ventilation. The house is opened up to clear the ozone until it is safe for anyone to go back in.
6. Re-check and pre-letting advice. We check the smell and the high-risk areas, advise on the right time to repaint, and explain how to look after the house while it waits for a new tenant.

Ozone Safety

• No people, pets or plants may be inside the house during ozone treatment.
• The house must be fully ventilated before anyone re-enters. The team will tell you when it is safe.
• We use a controlled dose, because very high concentrations over long periods can age rubber and some plastics. Sensitive electronics are covered or removed.
• Let the neighbours in adjoining townhouses know in advance, so they understand what is happening next door.

10 Reasons Landlords Should Restore a Flooded Rental Properly

1. Wet belongings left for weeks spread mold throughout the house, so both the source and the spread need to be dealt with.
2. Disinfection fogging reaches walls, under the stairs and inside cabinets where wiping by hand cannot.
3. Ozone treatment tackles the musty and muddy smell that new tenants notice first.
4. CHEMGENE HLD4H is used for surface disinfection without relying on harsh-smelling bleach.
5. It reduces the chance of mold returning after repainting, and of complaints from your next tenant.
6. The house is ready to let sooner, cutting the number of months without rent.
7. Older landlords do not have to breathe in large amounts of mold spores while cleaning on their own.
8. You have a record of the work, so you can tell prospective tenants with confidence that the house has been restored.
9. Areas with signs of rats and insects are dealt with, reducing a real hygiene risk.
10. You get advice on caring for the house while it is empty, along with information on residential ozone disinfection.

Before and After

A Simple Two-Week Recovery Timeline for Landlords

Every house is different, but having a rough timeline helps you plan your time, your budget and the date you can start advertising again. Here is a realistic sequence for a two-storey townhouse like Uncle Somsak's.

• Day 1: Document and secure. Photograph and video every room, check that the main breaker is off, and send the former tenant a list of the remaining items with photos. Ask an electrician to book an inspection.
• Days 2 to 4: Agree and clear. Once the tenant has confirmed, remove wet mattresses, sofas, rugs, cardboard and spoiled food. Arrange bulky waste collection through the district office or a licensed removal service. Wash out mud from floors, the lower part of the walls and the kitchen.
• Days 5 to 9: Dry out. Open the house during the day when you or someone you trust can be there, run fans, and use a dehumidifier if you have one. Let the electrician finish the inspection and any repairs before you rely on power for drying equipment.
• Days 10 to 11: Disinfection fogging and ozone treatment. With the house empty and drying, this is the ideal moment for professional treatment. The house needs to be left closed during the ozone stage and then ventilated.
• Days 12 to 14: Repairs and repainting. Once the walls are dry and treated, your painter and other tradespeople can begin. After that, the house is ready for photographs and viewings.

If the house was flooded deeper or for longer, or if the walls are taking more time to dry, the drying stage may take longer. It is better to wait a few extra days than to paint over damp walls and have to do the job twice.

Talking to Prospective Tenants About the Flood

In a neighbourhood like Nong Khaem, where many streets flooded in 2026, prospective tenants will almost certainly ask whether the house was affected. Being open about it tends to build trust rather than lose you a tenant. Explain how high the water reached, what was removed, and what was done afterwards, including the cleaning, disinfection fogging, ozone treatment, electrical inspection and repainting. Showing that the house was restored step by step, rather than simply painted over, reassures families with young children or older relatives in particular. It also protects you, because a tenant who knew the history from the start is far less likely to feel misled if they ever notice a small damp patch during the next rainy season.

Customer Voice

"My first plan was to call a truck, throw everything out and repaint. The team suggested I take photos first and send the tenant a list to confirm. Once the house was cleared they came to do the fogging and the ozone. The smell was mostly gone, and I felt much more comfortable showing the house to new people." Uncle Somsak, townhouse landlord in Nong Khaem (a representative scenario from our field work)

Looking After an Empty Rental While You Wait for a New Tenant

• Visit at least once a week if you can, open the house for a few hours and check the corners where mold appeared before.
• Keep drains topped up with water so sewer smells cannot come back up through dry traps.
• Do not store damp cardboard, mattresses or fabric furniture in the house while it is empty.
• Repaint only once the walls are fully dry. A painter can check moisture levels before starting.
• For future tenants, consider adding a short flood-season note to your welcome information: who to contact, how to switch off the main breaker, and a request to remove wet belongings or let you know quickly if they have to evacuate.

Frequently Asked Questions (FAQ)

Q: My tenant already told me to throw everything away. Do I need to wait?
A: It is wise to photograph all the items and send the tenant a list to confirm by message, with a clear date, to avoid misunderstandings later. If you are unsure about the legal side, consult a legal professional.

Q: Should fogging be done before or after the belongings are removed?
A: Remove the wet belongings and wash out the mud first. Disinfectant and ozone work much better in a house that is empty and starting to dry.

Q: When can I repaint?
A: Wait until the walls are completely dry and have been treated. A painter can check the moisture in the walls before starting.

Q: Can a new tenant move in right after the ozone treatment?
A: Once the house has been ventilated as the team advises, it can be used again. If repairs or painting are still pending, finish those before handing over the keys.

Q: Can you handle several rental houses at once?
A: Yes. We can plan the work around the number of properties and our schedule. Contact us by phone or LINE.

Q: Will my insurance cover the cleaning?
A: It depends entirely on your policy. Some home insurance policies include flood cover and some do not. Contact your insurer before you start clearing if possible, keep the photos and videos you took on the first day, and keep every receipt so you have what you need if a claim is possible.

Q: Does fogging and ozone replace repairs?
A: No. They deal with germs, spores and odour. Swollen doors, damaged flooring and electrical faults still need the right tradespeople.

Get Your Nong Khaem Rental Ready for a New Tenant

Talk to the World Health Disinfection team about rental house mold removal, disinfection fogging and ozone treatment after the flood. We are available every day.

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 odours and chemical residue
• CHEMGENE HLD4H spray disinfectant
• All articles
• External sources: WHO: Floods and health and Department of Disease Control, Thailand