Important note: This article is general information about restoring a home after a flood. It is not medical advice. Questions about treatment, medicines, food, vaccinations and when your child can safely come home must always be answered by the doctors and nurses who look after your child. If your child develops a fever, chills, unusual drowsiness, fast breathing, or any warning sign the medical team has told you about, follow the emergency plan the hospital gave you straight away, or call 1669.

A story from the field: the pale blue bedroom a mother prepared for her son

Khun Prae lives in a three-storey townhouse down a narrow soi off Phetchaburi Road in Ratchathewi with her husband and their two children. Her youngest, a six-year-old the family calls Khao Pan, is being treated for leukemia by a team of pediatric specialists. During chemotherapy cycles his doctors explained that his white blood cell count would drop from time to time, leaving him much more vulnerable to infection than other children his age. So the family did everything they could think of to make home a safe, happy place. They repainted the ground-floor bedroom a soft sky blue, laid down interlocking foam play mats, bought a new version of his favorite teddy bear, and set up a little drawing corner for the days when he could not go out.

In early October 2026 heavy rain fell for several days in a row. The drains in the soi could not keep up, and water crept into the house to a depth of about 25 centimeters. By chance Khao Pan was staying in hospital for treatment at the time. Khun Prae took her older daughter to stay at grandma's condo, and the house sat in standing water for three days before it finally drained away.

When she opened the front door again, the first thing that hit her was the smell: a heavy, musty odor mixed with the sour smell of mud. The foam play mats had swollen with water. The toy basket on the floor still had a puddle in the bottom. The teddy bear was so soaked it felt like a bag of wet sand. The freshly painted blue walls now carried a perfectly straight tide line all the way around the room. Five days later, small black dots began to appear in the corners of the walls and along the bottom of the door frame.

Khun Prae scrubbed the floor with bleach until her hands stung, and kept a fan running all day. Yet every morning the musty smell was still hanging in the air. What worried her most was that the doctors had said Khao Pan might be able to come home in about two weeks. She honestly did not know whether the room she had prepared with so much love was now safe enough for him.

Stories like this are playing out in many homes across Ratchathewi, around Phetchaburi, Phaya Thai, Pratunam and Ratchaprarop, where a lot of families live close to the hospitals their children visit regularly. After a flood, these parents are not only asking whether the house is clean. They are asking whether the house is ready for a child whose body has far less ability to fight off germs than anyone else in the family.

Why a house after floodwater matters so much for a child with low immunity

Children in cancer treatment, children who have recently had a bone marrow transplant, and children who take immune-suppressing medicines for other reasons are usually told by their doctors to be more careful about infections than other kids. Exactly how careful depends on the individual child, and only the medical team can answer that. From the point of view of the house, however, a flood leaves behind several kinds of risk that every parent should understand.

• Germs carried in by floodwater. Water that has flowed over roads and through drains brings bacteria from sewage into the house. Those germs settle on floors, in grout lines, around door frames and on anything that was sitting on the floor. They are linked with diarrheal illness and skin infections.
• Leptospirosis. Rats escaping the water often take shelter inside homes. Their urine, mixed into floodwater and mud, is the source of leptospirosis. The places to worry about most are under cabinets, behind the refrigerator and in piles of belongings that have not been cleared yet.
• Mold spores. Walls and furniture that stay damp start growing mold within days. Mold spores float in the air even when you cannot see any stain. In healthy people they may cause sneezing, a stuffy nose or allergy flare-ups. For people with very weak immunity, doctors often put particular emphasis on avoiding moldy spaces and the dust from building work.
• Dust from repairs. Scraping walls, tearing up floors or cutting moldy wood sends dust and spores through the whole house. This work should be finished before the child comes home, not done while the child is sleeping in the next room.

The World Health Organization notes that the health risks of a flood do not end when the water goes down, because moisture, germs and damage to buildings remain for some time afterwards. That matches exactly what our team sees in homes on the ground.

The real cost for parents right now is not only money

Time. Parents of a child with cancer already live by a packed calendar of blood tests, treatment sessions and follow-up appointments. Coming home every evening after a day at the hospital to scrub the house alone leads to exhaustion, and an exhausted parent is more likely to fall ill too.

Money. Toys and bedding that have to be thrown away need replacing. Moldy walls need repair. If the work is done the wrong way and the mold returns within a month, you pay for repainting all over again.

Peace of mind. The nagging feeling that the house is still not safe for your child leads many families to keep the child at a relative's place for longer, even though the child longs to sleep in their own room. Seeing a clear process, having someone help check the house, and having a record of what was done makes it much easier for parents to make decisions and to talk them through with the medical team.

Siblings. An older brother or sister who goes to school every day also needs a clean home, because children in the same house share the bathroom, the sofa and the toys.

Why the usual fixes are not enough in a home with an immunocompromised child

• Bleach on its own. It works on some smooth surfaces, but mixed too strong it leaves a harsh smell that irritates the airways, and mixed with certain bathroom cleaners it can release dangerous gas. It also cannot reach inside wood, into curtains or into the gaps you cannot see.
• Running fans to dry things out. Fans dry the surface, but they also blow mold spores all around the room, and the inside of a concrete wall stays damp for a long time.
• Air fresheners and scented gels. They only cover the smell for a while and do nothing about the source. Strong perfume can also bother a child who already feels nauseous from treatment.
• Painting over the stains. If the wall is still wet and the mold is still inside, new paint will bubble and the black spots will be back within weeks.
• Wiping toys with wet wipes. Fine for small plastic toys in daily life, but not enough for items that sat in floodwater for days.

Sort your child's room first: what to keep and what to let go

Before calling anyone to fog or ozone the house, sort out the things that got wet. No treatment can make every soaked item safe again if dirty water is trapped deep inside it. Here is the simple approach many families use, together with questions to the child's medical team.

• Usually thrown away: soft toys and pillows that were soaked in floodwater, foam play mats, rugs, mattresses that got wet, cardboard boxes, swollen picture books, and toys with hollow spaces where water can sit but which cannot be taken apart and washed.
• Usually washable: hard one-piece plastic toys, plastic building blocks, and your child's plates, bowls and water bottles. Wash them with clean water and detergent, disinfect them in a way that suits the material, and let them dry completely.
• Ask first: the much-loved teddy bear your child cannot sleep without. Some families buy an identical new one; others ask the medical team whether a particular washing method is enough. Try not to decide on feelings alone.
• Your child's medicines and medical supplies: any medicine that got wet or was stored somewhere damp, thermometers, line-care kits or a nebulizer should be checked with the pharmacist and nurses before you use them again, and everything must be taken out of the house before ozone treatment.

Take photos of what you throw away. They can be useful later when applying for assistance or making an insurance claim.

The solution: Chemgene HLD4H disinfection fogging and ozone treatment by the WHD team

World Health Disinfection (WHD) provides disinfection fogging and ozone treatment for homes after a flood. We do not replace mud removal or wall repairs. We come in after them, to deal with germs and odors in the places that hands and cloths cannot reach.

Ultra-low-volume (ULV) fogging uses CHEMGENE HLD4H, a disinfectant used in healthcare settings. It is released as a very fine mist that drifts into room corners, the gaps around furniture, under beds and onto high-touch surfaces such as door handles, light switches and stair rails.

Ozone treatment uses an ozone generator to fill a closed room with ozone gas. Because it is a gas, it reaches the spaces behind cabinets, the folds of curtains and into the texture of some materials, helping to destroy airborne mold spores and break down the molecules that cause musty odors. When the treatment time is over, ozone naturally reverts to oxygen and the room is then thoroughly ventilated.

Our step-by-step process, from survey to welcoming your child home

1. Survey and listen to your family's situation. We ask whether there is an immunocompromised child in the house, when the child is expected home and which rooms the child uses most, then walk through to check the water line, mold stains and the places that smell.
2. Advice on clean-up before fogging. We tell you which rugs or foam pieces should come out, which areas need all the mud washed away, and where a builder should make repairs first so the fogging actually works.
3. Disinfection fogging with Chemgene HLD4H. We cover floors, lower walls, door frames, under beds, bathrooms, the kitchen and high-touch points throughout the house, not just the child's room.
4. Closed-room ozone treatment. We treat the child's bedroom, the living room and any rooms with a musty smell, with nobody in the house and treatment time matched to the space.
5. Ventilation. Doors and windows are opened so fresh air can move through until there is no ozone smell left, before anyone comes back in.
6. Re-check and aftercare advice. We look again at the spots that used to smell or stain, advise on keeping humidity under control and arrange another check if anything still looks suspicious.

We recommend booking several days before your child's expected return. That leaves time for airing out, a final round of dust cleaning, and for you to walk through the house yourself with an easy mind.

10 reasons parents in Ratchathewi ask WHD to prepare the house before their child comes home

1. The team asks about your child's health situation first and plans the work so the child never needs to be inside during treatment.
2. We use Chemgene HLD4H, a disinfectant used in healthcare settings.
3. Fine-mist fogging reaches corners and gaps that wiping and mopping miss.
4. Ozone treatment tackles musty odor and airborne mold spores instead of just masking them.
5. No heavy perfume is left behind to bother a child who gets nauseous easily.
6. Honest advice on which toys and bedding to throw away and which can be washed.
7. We look after the whole house, because children do not stay only in their bedroom.
8. We always remind you to remove medicines and medical equipment before ozone treatment.
9. Add-on services such as dust mite removal for the new mattress and sofa.
10. Easy contact by phone and LINE, with appointment dates fitted around your child's hospital schedule.

Before and after

A customer's voice (example scenario)

"At first I thought I would scrub everything myself, but the more I scrubbed the less sure I felt. The team told us plainly that the foam mats and the soaked soft toys should go, then fogged the whole house and treated our son's room with ozone. When we went back in, the smell was gone. We shared what had been done with the nurse and planned his homecoming together. It took a huge weight off my shoulders."

— A mother of two, Phetchaburi area, Ratchathewi

Checklist before the day your child comes home

• Ask the medical team whether there are any special precautions for the home, and write them down.
• Finish dusty repair work, such as scraping walls or tearing up floors, first.
• Sort out the toys, bedding and other items in your child's room that got wet.
• Have the house fogged and ozone-treated with nobody inside, then ventilate it.
• Clean the air conditioners and replace filters that were in damp rooms.
• Keep checking for damp. If the smell or stains come back, ask the team for a re-check.
• Stick the hospital phone numbers and the emergency plan from the medical team on the fridge.

A few extra habits that help in the weeks after the flood

Once the house has been treated, everyday habits keep it that way. Leave shoes outside the front door so mud from the soi does not come back in. Keep the windows open for a while each morning when the weather allows, so moisture does not build up overnight. Wipe the bathroom dry after showers, and check the corners behind wardrobes once a week, because that is where mold likes to start again quietly. If you bought a new mattress, consider a mattress protector and regular dust mite care, especially in the first months.

It also helps to keep a simple notebook of what was done in the house and when: the date of fogging, the rooms that were ozone-treated, items thrown away, any repairs. When the doctors or nurses ask about the home environment, you will have clear answers rather than trying to remember everything during an already stressful appointment.

Frequently asked questions

Q: Can my child come home right after the fogging and ozone treatment?
A: The homecoming date must be decided by your child's medical team. On the house side, we recommend proper ventilation after ozone treatment and allowing several days before your child returns, so you can inspect the house and do a final dust clean.

Q: Do we need to treat the whole house, or is the child's bedroom enough?
A: Children share the bathroom, the living room and the dining table with everyone else. If the whole ground floor flooded, we recommend disinfection fogging across every area the water reached, plus ozone treatment for the rooms your child uses most and any rooms that smell.

Q: Does Chemgene HLD4H have a strong smell?
A: It does not have the harsh smell of bleach, but nobody should be in the area while it is being fogged, and surfaces should be left to dry as the team advises before use.

Q: Can we ozone-treat our child's favorite teddy bear and keep using it?
A: If it was soaked in floodwater, ozone can help with the smell but it cannot make dirty, water-logged stuffing clean again. Please ask your child's medical team. Many families choose to buy a new one instead.

Q: After ozone treatment, will the mold never come back?
A: Ozone is very effective at reducing spores and odor, but if the walls are still damp or there is a leak, mold can return. Moisture has to be fixed at the same time, with periodic checks.

Q: Our older child goes to school every day. What else should we do?
A: Hand washing when they get home, leaving shoes outside, and following the medical team's advice about siblings all help. The house itself should be clean throughout, as described above.

Get the house ready before your child comes home. Talk to the WHD team today.

Let us know there is a child with low immunity in the house and when they are expected home. We will help you plan the work so it is finished safely and on time.

See Disinfection Service - Click Here

Book Ozone Treatment - Click Here

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

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• External sources: WHO: Floods · Department of Disease Control, Thailand