A Story from the Field: Four Houses, Four Different Problems, One Morning

Khun Thanakorn is forty-eight years old and works an ordinary office job. Over the past ten years he has quietly saved, borrowed and renovated his way into a small property portfolio: four second-hand townhouses and semi-detached homes scattered around Rangsit, in Prachathipat and Rangsit sub-districts of Thanyaburi. His tenants are mostly factory supervisors, retail staff and a university lecturer with two young children. The rent that arrives each month covers his bank loans and is the backbone of his retirement plan.

When the 2026 floods reached Pathum Thani, water from the canals and overwhelmed drains entered all four housing estates within a few days of each other. Two tenant families moved out temporarily to stay with relatives. A third family gave notice and ended their lease. The fourth house was already empty, waiting for a new tenant.

On the first morning after the water receded, Khun Thanakorn drove from house to house. In the first, the water had only reached mid-shin, but the laminate floor had swollen and buckled. In the second, the water had come up almost to waist height; the plywood kitchen cabinets had puffed up and spots of green mold were creeping along the bottom of the walls. The third was a semi-detached house the tenants had locked up in a hurry. A soaked mattress lay on the floor of the downstairs bedroom, and when he opened the door a wave of musty, muddy air hit him so hard that he stepped back outside to breathe. The fourth, the empty one, had a clear tide line across every wall and black speckles spreading out from the corners of each room.

"I sat in my car and wondered which house to start with," he said later. "If I just fixed them one at a time, whenever I could, I would lose several months of rent before all four were done." His question is the same one being asked by many small investors across Thanyaburi, Khlong Luang, Lam Luk Ka and the wider Rangsit area, people who own more than one property and saw them all go under water at the same time. This article answers that question step by step.

The Real Problems Rental Owners Face After the Water Goes Down

From the outside, a flooded house that has been hosed down can look almost normal. For a landlord, the risk is that the visible mess is the smallest part of the problem. The bigger issues are the ones a future tenant will feel after they have signed the lease and moved their family in.

1. Health risks for your tenants

Floodwater does not just bring mud. It carries whatever was in the drains, septic tanks and streets it passed through. Bacteria such as E. coli can cause diarrhea and stomach illness. Standing water contaminated with rat urine is associated with leptospirosis, a disease that can enter the body through cuts and broken skin. Once the water leaves, moisture trapped in brick walls, under floors and inside furniture gives mold an ideal place to grow. Mold spores in the air can trigger allergies, asthma attacks and a lingering cough, especially in children, older people and anyone with a weak immune system. If a new tenant moves in and their toddler starts coughing every night, the landlord faces a far bigger problem than one more round of cleaning.

2. Lost income every day a unit sits empty

For an investor, one empty month means one month of rent that never comes back, while the mortgage, the estate maintenance fee and repair bills keep arriving. With four houses, slow recovery multiplies the damage four times. That is why planning the order of work, so that each house is ready to let as early as possible, matters almost as much as the quality of the repairs themselves.

3. Your reputation as a landlord

Many renters around Rangsit find homes through online groups, workplace chats and recommendations from colleagues. If a new tenant moves in and finds a musty smell returning or mold coming back on the walls, that story travels quickly. It does not only affect the one house; it can make your other properties harder to let, because people remember the owner's name.

4. Your own time and energy

Most small rental investors also have a full-time job. Taking leave to visit each house, juggling several different contractors, answering worried calls from tenants and making decisions under pressure is exhausting, and tired people make expensive mistakes. Having one team handle disinfection and ozone treatment for every house under a single plan removes a large part of that burden.

Why the Usual Quick Fixes Are Not Enough for Rental Homes

Landlords are practical people, and after a flood the instinct is to do whatever is fastest and cheapest. Unfortunately, several of the most common quick fixes create problems that show up weeks later, usually after a tenant has already moved in.

• Pouring bleach and calling it done. Bleach can kill some germs on smooth, hard surfaces, but it does not reach the gaps between floor tiles, the space under kitchen cabinets or the cavity behind skirting boards. It also leaves a sharp chemical smell that prospective tenants dislike, and it can damage some materials.
• Running fans to dry everything. Fans dry the surface, but moisture deep inside brick walls and under floors stays where it is. Worse, the moving air can spread mold spores to rooms that were not affected.
• Spraying air freshener before a viewing. A pleasant scent can cover a musty smell for a few hours. The tenant who actually lives there will notice the smell return on the first night they close the windows to sleep.
• Painting over water stains straight away. If the wall is still damp, new paint will bubble and mold will grow underneath it within weeks. You lose the money spent on paint and labor, and a tenant may feel that the problem was deliberately hidden.
• Using a different method for every house. When each property is handled by a different handyman with a different approach, the results are uneven. Some houses develop repeat problems, and you cannot give tenants a consistent, confident answer about what was done.

None of these steps is useless on its own. Cleaning, drying and repainting all have their place. The issue is that they do not deal with the germs and spores spread through the air and into hidden corners, and they do not break down odor that has soaked into walls, ceilings and fabrics.

The Solution: Chemgene HLD4H Fogging and Ozone Treatment Under One Portfolio Plan

World Health Disinfection (WHD) provides a professional disinfection fogging service using CHEMGENE HLD4H disinfectant. The solution is applied with ULV (ultra-low volume) foggers that create droplets fine enough to drift into corners, under cabinets, behind furniture and into joints that a cloth or mop will never reach. This is followed by our ozone treatment service, which uses a controlled concentration of ozone gas to tackle airborne mold spores and break down the odor molecules that have soaked into walls, ceilings and curtains.

The two steps work together. Fogging deals with germs on surfaces throughout the house, while ozone reaches the air and the porous materials where musty smells live. Used together after proper mud removal and drying, they give a rental home a genuinely fresh start instead of a cosmetic one.

How we work with owners of several rental homes

1. Survey and prioritize. Our team visits every property, records how high the water reached, where mold has appeared and what condition the materials are in. Together with the owner we set an order of work. For example, a house whose tenant is waiting to move back in goes first, while a house that needs its floor or cabinets removed waits until the contractor has finished that job.
2. Advice on mud removal and stripping damaged materials. Mattresses, carpets, swollen gypsum ceiling boards and puffed-up plywood cabinets should be taken out first. These materials soak up contaminated water and are very difficult to disinfect completely.
3. ULV fogging of the whole house. We fog Chemgene HLD4H across floors, the lower parts of walls, bathrooms, kitchens, under the stairs and the car port, so that no area is missed.
4. Closed-room ozone shock treatment. Doors and windows are closed and the ozone generator runs for a period suited to the size of the house. During treatment there must be no people, pets or plants inside. Sensitive electronics should be covered or removed, and we use a controlled dose to limit any effect on rubber and plastic parts.
5. Ventilation before re-entry. Doors and windows are opened to air the house thoroughly, following our team's guidance, before anyone goes back inside.
6. Re-check before handover. We return to check for odor and mold. If any area still shows high moisture, we advise on what else needs to be done before a tenant moves in.

The advantage of handling the whole portfolio with one team is consistency. Every house receives the same standard of work, the schedule can be planned in advance, and you end up with a record of each property's condition that you can share openly with future tenants.

Practical Tips for Scheduling Work So Rent Starts Flowing Again

Sort your houses into three groups. The first group is houses where the water was shallow and no materials need to be removed. These can be treated as soon as the mud is out. The second group is houses where some flooring or cabinets must be stripped. Let the contractor remove those first, then fog and ozone-treat. The third group is houses with heavy damage that need time for the structure to dry and for major repairs. For these, a first round of fogging during the waiting period reduces germs and odor, and a second ozone treatment just before handover makes sure the house is fresh for the new tenant.

Coordinate with existing tenants. If a good tenant wants to return, tell them the date and time of the work, ask them to remove valuables and pets beforehand, and explain that the house must be ventilated before they move back in. Clear communication is one of the best ways to keep a reliable tenant.

Take before-and-after photos of every house. Keep a set of photos for each property showing its condition before and after treatment. These are useful for any insurance claim you may have and are very persuasive when a prospective tenant asks, "Did this house flood?"

Do not rush the painting or wallpaper. Wait until walls are truly dry. Decorating too early is one of the most common reasons landlords end up paying twice. Waiting a few extra weeks is almost always cheaper than redoing the work.

Think about the whole street, not just the house. After floods, mosquitoes often increase in housing estates with blocked drains and standing water. If your properties are in the same area, it can make sense to add a mosquito control visit to the same schedule so tenants are not greeted by swarms in the evening.

What Prospective Tenants Ask After a Flood, and How to Answer

In the months after a flood, almost every person viewing a rental home in Rangsit will ask some version of the same questions. Being ready with honest, specific answers is one of the simplest ways to turn a viewing into a signed lease.

"Did this house flood?" Say yes if it did, and say how high the water came. Then explain what was removed, how the house was disinfected and treated with ozone, and when it was re-checked. A clear answer sounds far more trustworthy than a vague one.

"Is there still mold?" Invite them to look inside cabinets, behind doors and along the base of the walls. If you have photos from before and after treatment, show them side by side.

"Is it safe for my children?" Explain that the house was fogged with disinfectant, treated with ozone while empty, and thoroughly ventilated before anyone went back in. Families with young children or elderly parents appreciate knowing that the work was done properly, not just quickly.

10 Reasons Rental Investors Around Thanyaburi Choose WHD Fogging and Ozone Treatment

1. One plan for every house, so you do not have to coordinate several different contractors.
2. We use CHEMGENE HLD4H, a disinfectant designed for high-level disinfection work.
3. ULV fogging reaches under kitchen cabinets, beneath stairs and into corners that cloths cannot reach.
4. Ozone treatment breaks down musty odors in walls and curtains rather than simply masking them.
5. It reduces the risk of a new tenant finding mold returning and filing a complaint.
6. Work is scheduled by income priority, so the houses that can be let first are treated first.
7. Clear ozone safety procedures reassure returning tenants and their families.
8. Honest advice on which materials to remove and which to keep helps you avoid paying for the same repair twice.
9. For furnished rentals, our dust mite removal service can treat mattresses and sofas that were not submerged.
10. Mosquitoes usually increase after floods, and our mosquito spraying service can be added to the same plan.

Before and After: A Rental Home Recovery

What a Rental Owner Told Us

"At first I thought I would save money by doing each house myself, one at a time. After talking with the team, I saw how much a clear order of work helped. The house with shallow water was ready for the old tenant to move back first, and the one that needed a new floor had a plan waiting for it. When people came to view the empty house and asked about the flood, I could simply show them the before and after photos. It made those conversations much easier."

— Khun Thanakorn, owner of four rental homes in Rangsit (a representative scenario based on field experience)

Frequently Asked Questions

Q: I own several houses. Do they all have to be treated on the same day?
A: No. It is better to survey every house first and then set an order based on readiness. Houses that do not need materials removed can go first; houses that need major repairs are treated once the damaged materials have been stripped out.

Q: How long does a returning tenant need to stay away during ozone treatment?
A: Nobody, including pets, may be inside while ozone treatment is running, and plants should be removed too. After treatment the house must be ventilated according to our team's guidance before anyone goes back in. The total time depends on the size of the house and the severity of the problem, and we will tell you before work begins.

Q: After disinfection, do I still need to repaint?
A: If walls are stained or the paint has bubbled, repainting may be needed, but it should only be done once the walls are completely dry. Fogging and ozone treatment deal with germs and odor; they do not replace repairs to the wall surface.

Q: My rental is furnished. Can I keep mattresses and sofas that got wet?
A: Mattresses and sofas that were soaked in floodwater usually hold germs and moisture deep inside, which are very hard to deal with. In most cases replacing them is recommended. Furniture that was only lightly splashed can be assessed piece by piece.

Q: Will ozone treatment affect appliances in the rental house?
A: We use a controlled ozone dose and recommend covering or removing sensitive electronics before treatment. Any electrical appliance that was submerged must be checked by a qualified electrician before it is used again.

Q: Should I tell new tenants that the house flooded?
A: Yes. Be honest and show them what was done to restore the house. Openness builds trust and reduces the chance of disputes later on.

Q: Is this service only for Thanyaburi?
A: No. We also work in Khlong Luang, Lam Luk Ka, Mueang Pathum Thani, Bangkok and other flood-affected provinces. Contact us to check scheduling for your area.

Ready to Plan the Recovery of Every Rental Home?

Talk to the WHD team about surveying your rental properties in Thanyaburi, Rangsit, Khlong Luang and Lam Luk Ka, and set an order of work that gets each house earning again as quickly as possible.

View Disinfection Service – Click Here

Book Ozone Treatment – Click Here

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

A Checklist You Can Use for Each Property

To keep things organized across several houses, many owners find it helpful to use the same simple checklist for every property. Print it, save it on your phone, or share it with whoever is helping you.

• Record the highest water level in each room, with a photo and the date.
• List items that must be removed: mattresses, carpets, swollen boards, soaked curtains.
• Note every spot where mold is visible, including inside cabinets and behind the fridge.
• Have an electrician confirm the wiring and sockets are safe before power is turned back on.
• Book fogging and ozone treatment, and confirm that the house will be empty of people, pets and plants.
• Plan ventilation time before anyone re-enters.
• Re-check for odor and mold a few weeks later, especially after a weekend when the house is closed.
• Only then schedule painting, decorating and viewings.

Following the same list for every house makes it much easier to see which properties are ready, which are waiting and which need more attention. It also gives you a clear story to tell tenants and, if relevant, your insurer.

Related Links

• Ozone disinfection for residential homes
• Ozone treatment for odors and chemical residue
• Master Ozone Generator
• All articles

Health reference: World Health Organization (WHO): Floods fact sheet · Department of Disease Control, Thailand